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This document is a Mac OS X manual page. Manual pages are a command-line technology for providing documentation. You can view these manual pages locally using the man(1) command. These manual pages come from many different sources, and thus, have a variety of writing styles. This manual page is associated with the Mac OS X developer tools. The software or headers described may not be present on your Mac OS X installation until you install the developer tools package. This package is available on your Mac OS X installation DVD, and the latest versions can be downloaded from developer.apple.com. For more information about the manual page format, see the manual page for manpages(5). |
javadoc(1) javadoc(1)
NAME
javadoc - Java API documentation generator
SYNOPSIS
javadoc [ options ] [ packagenames ] [ sourcefilenames ] [ -subpackages pkg1:pkg2:... ] [ @argfiles
]
PARAMETERS
Arguments can be in any order.
options Command-line options, as specified in this document. To see a typical use of javadoc
options, see Real World Example.
packagenames A series of names of packages, separated by spaces, such as java.lang
java.lang.reflect java.awt. You must separately specify each package you want to doc-ument. document.
ument. The Javadoc tool uses -sourcepath to look for these package names. The
Javadoc tool does not recursively traverse subpackages. Wildcards such as asterisks
(*) are not allowed. See EXAMPLES, Documenting One or More Packages.
sourcefilenames
A series of source file names, separated by spaces, each of which can include paths
and wildcards such as asterisk (*). The Javadoc tool will process every file whose
name ends with .java , and whose name, when stripped of that suffix, is actually a
legal class name (see Identifiers). Therefore, you can name files with dashes (such
as X-Buffer), or other illegal characters, to prevent them from being documented.
This is useful for test files and files generated from templates. The path that pre-cedes precedes
cedes the source file name determines where javadoc will look for the file. The
Javadoc tool does not use -sourcepath to look for these source file names.) For exam-ple, example,
ple, passing in Button.java is identical to ./Button.java. An example source file
name with a full path is /home/src/java/awt/Graphics*.java. See EXAMPLES, Documenting
One or More Classes. You can also mix packagenames and sourcefilenames, as in EXAM-PLES, EXAMPLES,
PLES, Documenting Both Packages and Classes.
-subpackages pkg1:pkg2:...
Generates documentation from source files in the specified packages and recursively in
their subpackages. An alternative to supplying packagenames or sourcefilenames.
@argfiles One or more files that contain a list of Javadoc options, packagenames and sourcefile-names sourcefilenames
names in any order. Wildcards (*) and -J options are not allowed in these files.
DESCRIPTION
The Javadoc tool parses the declarations and documentation comments in a set of Java source files and
produces a corresponding set of HTML pages describing (by default) the public and protected classes,
nested classes (but not anonymous inner classes), interfaces, constructors, methods, and fields.
You can run the Javadoc tool on entire packages, individual source files, or both. In the first
case, you pass in as an argument to javadoc a series of package names. In the second case, you pass
in a series of source (.java) file names. See EXAMPLES at the end of this document.
NOTE - When you pass in package names to the Javadoc tool, it currently processes all .java
classes in the specified package directories, even if the .java files are code examples or
other classes that are not actually members of the specified packages. It does not parse each
.java file for a package declaration; we may add this parsing in a future release.
During a run, the Javadoc tool automatically adds cross-reference links to package, class and member
names that are being documented as part of that run. Links appear in several places:
Declarations (return types, argument types, field types)
"See Also" sections generated from @see tags
In-line text generated from {@link} tags
Exception names generated from @throws tags
Specified by links to members in interfaces and Overrides links to members in classes
Summary tables listing packages, classes and members
Package and class inheritance trees
The index
You can add hyperlinks to existing text for classes not included on the command line (but generated
separately) by way of the -link and -linkoffline options.
The Javadoc tool produces one complete document each time it is run; it cannot do incremental builds
- that is, it cannot modify or directly incorporate results from previous runs of Javadoc. However,
it can link to results from other runs, as just mentioned.
As implemented, the Javadoc tool requires and relies on the java compiler to do its job. The Javadoc
tool calls part of javac to compile the declarations, ignoring the member implementation. It builds
a rich internal representation of the classes, including the class hierarchy, and "use" relation-ships, relationships,
ships, then generates the HTML from that. The Javadoc tool also picks up user-supplied documentation
from documentation comments in the source code.
In fact, the Javadoc tool will run on .java source files that are pure stub files with no method bod-ies. bodies.
ies. This means you can write documentation comments and run the Javadoc tool in the earliest stages
of design while creating the API, before writing the implementation.
Relying on the compiler ensures that the HTML output corresponds exactly with the actual implementa-tion, implementation,
tion, which may rely on implicit, rather than explicit, source code. For example, the Javadoc tool
will document default constructors (section 8.6.7 of Java Language Specification) that are present in
the .class files but not in the source code.
In many cases, the Javadoc tool allows you to generate documentation from source files whose code is
incomplete or erroneous. This is a benefit that enables you to generate documentation before all
debugging and troubleshooting is done. For example, according to the Java Language Specification, a
class that contains an abstract method should itself be declared abstract. The Javadoc tool does not
check for this, and would proceed without a warning, whereas the javac compiler stops on this error.
The Javadoc tool does do some primitive checking of doc comments. Use the DocCheck doclet to check
the doc comments more thoroughly.
When the Javadoc tool builds its internal structure for the documentation, it loads all referenced
classes. Because of this, the Javadoc tool must be able to find all referenced classes, whether
bootstrap classes, extensions, or user classes. For more about this, see How Classes Are Found.
Generally speaking, classes you create must either be loaded as an extension or in the Javadoc tool's
class path.
javadoc Doclets
You can customize the content and format of the Javadoc tool's output by using doclets. The Javadoc
tool has a default "built-in" doclet, called the standard doclet, that generates HTML-formatted API
documentation. You can modify or subclass the standard doclet, or write your own doclet to generate
HTML, XML, MIF, RTF or whatever output format you'd like. Information about doclets and their use is
at the following locations:
Javadoc Doclets
The -doclet command-line option
When a custom doclet is not specified with the -doclet command line option, the Javadoc tool uses the
default standard doclet. The Javadoc tool has several command line options that are available
regardless of which doclet is being used. The standard doclet adds a supplementary set of command
line options. Both sets of options are described below in the options section.
Related Documentation and Doclets
Javadoc Enhancements for details about improvements added in Javadoc 1.4.
Javadoc FAQ for answers to common questions, information about Javadoc-related tools and work-arounds workarounds
arounds for bugs.
How to Write Doc Comments for Javadoc for more information about Sun conventions for writing docu-mentation documentation
mentation comments.
Requirements for Writing API Specifications - Standard requirements used when writing the Java 2
Platform Specification. It can be useful whether you are writing API specifications in source fiel
documentation comments or in other formats. It covers requirements for packages, classes, inter-faces, interfaces,
faces, fields and methods to stisfy testable assertions.
Documentation Comments Specification - The original specification on documentation comments, Chap-ter Chapter
ter 18, Documentation Comments, in the Java Language Specification, First Edition, by James
Gosling, Bill Joy and Guy Steele. (This chapter was removed from the second edition.)
DocCheck Doclet - Check doc comments in source files and generates a report listing the errors and
irregularities it finds. It is part of the Sun Doc Check Utilities.
MIF Doclet - Can automate the generation of API documentation in MIF, FrameMaker and PDF formats.
MIF is Adobe FrameMaker's interchange format.
Terminology
A few terms have specific meanings within the context of the Javadoc tool:
generated document
The document generated by the javadoc tool from the doc comments in Java source code.
The default generated document is in HTML and is created by the standard doclet.
name A name in the Java Language, namely the name of a package, class, interface, field,
constructor, or method. A name can be fully-qualified, such as
java.lang.String.equals(java.lang.Object), or partially-qualified, such as
equals(Object).
documented classes
The classes and interfaces for which full documentation is generated during a javadoc
run. To be documented, the source files must be available, and either their source
filenames or package names must be passed into the javadoc command. We also refer to
these as the classes included in the javadoc run, or the included classes.
inlcuded classes
Classes and interfaces whose source filenames or package names are passed into the
javadoc command.
excluded classes
Classes and interfaces whose source filename or package names are not passed into the
javadoc command.
referenced classes
The classes and interfaces that are explicitly referred to in the definition (imple-mentation) (implementation)
mentation) or doc comments of the documented classes and interfaces. Examples of ref-erences references
erences include return type, parameter type, cast type, extended class, implemented
interface, imported classes, classes used in method bodies, @see, {@link},
{@linkplain}, and {@inheritDoc} tags. (Notice this definition has changed since 1.3.)
tags) do not qualify as referenced classes. When thE Javadoc tool is run, it should
load into memory all of the referenced classes in javadoc's bootclasspath and class-path. classpath.
path. (The Javadoc tool prints a "Class not found" warning for referenced classes not
found.) The Javadoc tool can derive enough information from the .class files to
determine their existence and the fully qualified names of their members.
external referenced classes
The referenced classes whose documentation not being generated during a javadoc run.
In other words, these classes are not passed into the Javadoc tool on the comand line.
Links for names in the generated documentation to those classes are said to be exter-nal external
nal references or external links. For example, if you run the Javadoc tool on only
the java.awt package, then any class in java.lang, such as Object, is an external ref-erenced referenced
erenced class. External referenced classes can be linked to using the -link and
-linkoffline options. An important property of an external referenced class is that
its source comments are normally not available to the Javadoc run. In this case, these
comments cannot be inherited.
Source Files
The Javadoc tool will generate output originating from four different types of "source" files: Java
language source files for classes (.java), package comment files, overview comment files, and miscel-laneous miscellaneous
laneous unprocessed files.
Class Source Code Files
Each class or interface and its members can have their own documentation comment, contained in a
.java file. For more details about these doc commments, see Documentation Comments below.
Package Comment Files
Each package can have its own documentation comment, contained in its own "source" file, that the
Javadoc tool will merge into the package summary page that it generates. You typically include in
this comment any documentation that applies to the entire package.
To create a package comment file, you must name it package.html and place it in the package directory
in the source tree along with the .java files. The Javadoc tool will automatically look for this
filename in this location. Notice that the filename is identical for all packages. For explicit
details, see the example of package.html.
The content of the package comment file is one big documentation comment, written in HTML, like all
other comments, with one exception: The documentation comment should not include the comment separa-tors separators
tors /** and */ or leading asterisks. When writing the comment, you should make the first sentence a
summary about the package, and not put a title or any other text between <body> and the first sen-tence. sentence.
tence. You can include package tags; as with any documentation comment, all tags except {@link} must
appear after the description. If you add a @see tag in a package comment file, it must have a fully
qualified name.
When the Javadoc tool runs, it automatically looks for this file; if found, the Javadoc tool does the
following:
Copies all content between <body> and </body> tags for processing.
Processes any package tags that are present.
Inserts the processed text at the bottom of the package summary page it generates, as shown in
Package Summary.
Copies the first sentence of the package comment to the top of the package summary page. It also
adds the package name and this first sentence to the list of packages on the overview page, as
shown in Overview Summary. The end-of-sentence is determined by the same rules used for the end of
the first sentence of class and member descriptions.
Overview Comment File
Each application or set of packages that you are documenting can have its own overview documentation
comment, kept in its own "source" file, that the Javadoc tool will merge into the overview page that
it generates. You typically include in this comment any documentation that applies to the entire
application or set of packages.
To create an overview comment file, you can name the file anything you want, typically overview.html,
and place it anywhere, typically at the top level of the source tree. Notice that you can have mul-tiple multiple
tiple overview comment files for the same set of source files, in case you want to run javadoc multi-ple multiple
ple times on different sets of packages. For example, if the source files for the java.applet pack-age package
age are contained in /home/user/src/java/applet directory, you could create an overview comment file
at /home/user/src/overview.html.
The content of the overview comment file is one big documentation comment, written in HTML, like the
package comment file described previously. See that description for details. To reiterate, when
writing the comment, you should make the first sentence a summary about the application or set of
packages, and not put a title or any other text between <body> and the first sentence. You can
include overview tags; as with any documentation comment, all tags except {@link} must appear after
the description. If you add a @see tag, it must have a fully-qualified name.
When you run the Javadoc tool, you specify the overview comment file name with the -overview option.
The file is then processed, similar to that of a package comment file:
Copies all content between <body> and </body> tags for processing.
Processes any overview tags that are present.
Inserts the processed text at the bottom of the overview page it generates, as shown in Overview
Summary.
Copies the first sentence of the overview comment to the top of the overview summary page.
Miscellaneous Unprocessed Files
You can also include in your source any miscellaneous files that you want the Javadoc tool to copy to
the destination directory. These typically include graphic files (for example, Java source (.java)
and class (.class) files) and self-standing HTML files whose content would overwhelm the documenta-tion documentation
tion comment of a normal Java source file.
To include unprocessed files, put them in a directory called doc-files, which can be a subdirectory
of any package directory. You can have one such subdirectory for each package. You might include
images, example code, source files, .class files, applets, and HTML files. For example, if you want
to include the image of a button button.gif in the java.awt.Button class documentation, you place
that file in the /home/user/src/java/awt/doc-files/ directory. Notice the doc-files directory should
not be located at /home/user/src/java/doc-files because java is not a package - that is, it does not
directly contain any source files.
All links to these unprocessed files must be hard-coded, because the Javadoc tool does not look at
the files - it simply copies the directory and all its contents to the destination. For example, the
link in the Button.java doc comment might look like:
/**
* This button looks like this:
* <img src="doc-files/Button.gif">
*/
Test Files and Template Files
Some developers have indicated they want to store test files and templates files in the source tree
near their corresponding source files. That is, they would like to put them in the same directory,
or a subdirectory, of those source files.
If you run the Javadoc tool by explicitly passing in individual sourcefilenames, you can deliberately
omit test and templates files andprevent them from being processed. However, if you are passing in
package names or wildcards, you need to follow certain rulesto ensure these test files and templates
files are not processed.
Test files differ from template files in that the former arelegal, compilable source files, while the
latter are not, but may end with ".java".
Test files -Often filesOften
Often developers want to put compilable, runnable test files for a given package in the same
directory as the source files for that package. But they want the test files to belong to a
package other than the source file package, such as the unnamed package (so test files have no
package statement or a different package statement from the source). In this scenario, when
the source is being documented by specifying its package name specified on the command line,
the test files will cause warnings or errors. You need to put such test files in a subdirec-tory. subdirectory.
tory. For example, if you want to add test files for source files in com.package1 put them in
a subdirectory that would be an invalid package name (because it contains a hyphen):
com/package1/test-files/
The test directory will be skipped by the Javadoc tool with no warnings.
If your test files contain doc comments, you can set up a separate run of the Javadoc tool to produce
documentation of the test files by passing in their test source filenames with wildcards, such as
com/package/ est-filesjava .
Tempaltes for source files -Template filesTemplate
Template files have names that often end in ".java" and are not compilable. If you have a tem-plate template
plate for a source file that you want to keep in the source directory, you can name it with a
dash (such as Buffer-Template.java ), or any other illegal Java character, to prevent it from
being processed. This relies on the fact that the Javadoc tool will only process sourcefiles
whose name, when stripped of the ".java" suffix, is actually a legal class name (see Identi-fiers Identifiers
fiers ).
Generated Files
By default, javadoc uses a standard doclet that generates HTML-formatted documentation. This doclet
generates the following kinds of files (where each HTML "page" corresponds to a separate file). Note
that javadoc generates files with two types of names: those named after classes/interfaces, and those
that are not (such as package-summary.html). Files in the latter group contain hyphens to prevent
file name conflicts with those in the former group.
Basic Content Pages
One class or interface page (classname.html) for each class or interface it is documenting.
One package page (package-summary.html) for each package it is documenting. The Javadoc tool
includes any HTML text provided in a file named package.html in the package directory of the source
tree.
One overview page (overview-summary.html) for the entire set of packages. This is the front page
of the generated document. The Javadoc tool includes any HTML text provided in a file specified
with the -overview option. Note that this file is created only if you pass into javadoc two or
more package names. For further explanation, see HTML Frames below.
Cross-Reference Pages
One class hierarchy page for the entire set of packages (overview-tree.html). To view this, click
on "Overview" in the navigation bar, then click on "Tree".
One class hierarchy page for each package (package-tree.html). To view this, go to a particular
package, class or interface page; click "Tree" to display the hierarchy for that package.
One "use" page for each package (package-use.html) and a separate one for each class and interface
(class-use/classname.html). This page describes what packages, classes, methods, constructors, and
fields use any part of the given class, interface, or package. Given a class or interface A, its
"use" page includes subclasses of A, fields declared as A, methods that return A, and methods and
constructors with parameters of type A. You can access this page by first going to the package,
class, or interface, then clicking on the "Use" link in the navigation bar.
A deprecated API page (deprecated-list.html) listing all deprecated names. (A deprecated name is
not recommended for use, generally due to improvements, and a replacement name is usually given.
Deprecated APIs may be removed in future implementations.)
A constant field values page (constant-values.html) for the values of static fields.
A serialized form page (serialized-form.html) for information about serializable and externalizable
classes. Each such class has a description of its serialization fields and methods. This informa-tion information
tion is of interest to re-implementors, not to developers using the API. While there is no link in
the navigation bar, you can get to this information by going to any serialized class and clicking
"Serialized Form" in the "See also" section of the class description. The standard doclet automat-ically automatically
ically generates a serialized form page: any class (public or non-public) that implements Serializ-able Serializable
able is included, along with readObject and writeObject methods, the fields that are serialized,
and the doc comments from the @serial, @serialField, and @serialData tags. Public serializable
classes can be excluded by marking them (or their package) with @serial exclude, and package-pri-vate package-private
vate serializable classes can be included by marking them (or their package) with @serial include.
As of 1.4, you can generate the complete serialized form for public and private classes by running
javadoc without specifying the -private option.
An index (index-*.html) of all class, interface, constructor, field and method names, alphabeti-cally alphabetically
cally arranged. This is internationalized for Unicode and can be generated as a single file or as
a separate file for each starting character (such as A-Z for English).
Support Files
A help page (help-doc.html) that describes the navigation bar and the above pages. You can provide
your own custom help file to override the default using -helpfile.
One index.html file that creates the HTML frames for display. This is the file you load to display
the front page with frames. This file itself contains no text content.
Several frame files (*-frame.html) containing lists of packages, classes and interfaces, used when
HTML frames are being displayed.
A package list file (package-list), used by the -link and -linkoffline options. This is a text
file, not HTML, and is not reachable through any links.
A style sheet file (stylesheet.css) that controls a limited amount of color, font family, font
size, font style, and positioning on the generated pages.
A doc-files directory that holds any image, example, source code, or other files that you want
copied to the destination directory. These files are not processed by the Javadoc tool in any man-ner, manner,
ner, that is, any javadoc tags in them will be ignored. This directory is not generated unless it
exists in the source tree.
HTML Frames
The Javadoc tool will generate either two or three HTML frames, as shown in the figure below. When
you pass source files (*.java) or a single package name as arguments into the javadoc command, it
creates only one frame (C) in the left-hand column, that is, the list of classes. When you pass into
javadoc two or more package names, it creates a third frame (P) listing all packages, as well as an
overview page (Detail). This overview page has the file name, overview-summary.html. Thus, this
file is created only if you pass in two or more package names. You can bypass frames by clicking on
the "No Frames" link or entering at overview-summary.html.
If you are unfamiliar with HTML frames, you should be aware that frames can have focus for printing
and scrolling. To give a frame focus, click on it. Then, on many browsers the arrow keys and page
keys will scroll that frame, and the print menu command will print it.
------------ ------------|C| -----------|C|
|C| Detail | |P| Detail |
| | | | | |
| | | |-| |
| | | |C| |
| | | | | |
| | | | | |
------------ ------------javadoc -----------javadoc
javadoc *.java javadoc java.lang java.awt
Load one of the following two files as the starting page depending on whether you want HTML frames or
not:
index.html (for frames)
overview-summary.html (for no frames)
Generated File Structure
The generated class and interface files are organized in the same directory hierarchy as Java source
files and class files. This structure is one directory per subpackage.
For example, the document generated for the class java.applet.Applet would be located at
java/applet/Applet.html. The file structure for the java.applet package follows, given that the des-tination destination
tination directory is named apidocs. All files that contain the word "frame" appear in the upper-left upperleft
left or lower-left frames, as noted. All other HTML files appear in the right-hand frame.
NOTE: Directories are shown in bold. The asterisks (*) indicate the files and directories that are
omitted when the arguments to javadoc are source file names (*.java) rather than package names.
Also, when arguments are source file names, package-list is created but is empty. The doc-files
directory is not created in the destination unless it exists in the source tree.
apidocs Top directory
index.html Initial page that sets up HTML frames
* overview-summary.html Lists all packages with first sentence summaries
overview-tree.html Lists class hierarchy for all packages
deprecated-list.html Lists deprecated API for all packages
constant-values.html Lists values of static fields for all packages
serialized-form.html Lists serialized form for all packages
* overview-frame.html Lists all packages, used in upper-left frame
allclasses-frame.html Lists all package classes, lower-left frame
help-doc.html Lists user help for how pages are organized
index-all.html Default index created w/o -splitindex option
index-files Directory created with -splitindex option
index-<number>.html Index files created with -splitindex option
package-list Lists package names used only for resolving external refs
stylesheet.css HTML style sheet for defining fonts, colors, positions
java Package directory
applet Subpackage directory
Applet.html Page for Applet class
AppletContext.html Page for AppletContext interface
AppletStub.html Page for AppletStub interface
AudioClip.html Page for AudioClip interface
* package-summary.html Lists classes with first sentence summaries
* package-frame.html Lists package classes, lower left-hand frame
* package-tree.html Lists class hierarchy for this package
package-use Lists where this package is used
doc-files Directory holding image & example files
class-use Directory holding pages API is used
Applet.html Page for uses of Applet class
AppletContext.html Page for uses of AppletContext interface
AppletStub.html Page for uses of AppletStub interface
AudioClip.html Page for uses of AudioClip interface
src-html Source code directory
java Package directory
applet Subpackage directory
Applet.html Page for Applet source code
AppletContext.html Page for AppletContext source code
AppletStub.html Page for AppletStub source code
AudioClip.html Page for AudioClip source code
Generated API Declarations
The Javadoc tool generates a declaration at the start of each class, interface, field, constructor,
and method description. This declaration is the declaration for that API item. For example, the dec-laration declaration
laration for the Boolean class is:
public final class Boolean
extends Object
implements Serializable
and the declaration for the Boolean.valueOf method is:
public static Boolean valueOf(String s)
The Javadoc tool can include the modifiers public, protected, private, abstract, final, static, tran-sient, transient,
sient, and volatile, but not synchronized or native. These last two modifiers are considered imple-mentation implementation
mentation detail and not part of the API specification.
Rather than relying on the keyword synchronized, APIs should document their concurrency semantics in
the comment description, as in "a single Enumeration cannot be used by multiple threads concur-rently". concurrently".
rently". The document should not describe how to achieve these semantics. As another example, while
Hashtable should be thread-safe, there's no reason to specify that we achieve this by synchronizing
all of its exported methods. We should reserve the right to synchronize internally at the bucket
level, thus offering higher concurrency.
Documentation Comments
The original "Documentation Comments Specification" can be found under related documentation.
Commenting the Source Code
You can include documentation comments ("doc comments") in the source code, ahead of declarations for
any entity (classes, interfaces, methods, constructors, or fields). You can also create doc comments
for each package and another one for the overview, though their syntax is slightly different. Doc
comments are also known as Javadoc comments. A doc comment consists of the characters between the
characters /** that begin the comment and the characters */ that end it. Leading asterisks are
allowed on each line and are described further below. The text can continue onto multiple lines.
/**
* This is the typical format of a simple documentation comment
* that spans two lines.
*/
To save space you can put a comment on one line:
/** This comment takes up only one line. */
Placement of comments - Documentation comments are recognized only when placed immediately before
class, interface, constructor, method, or field declarations (see the class example, method example,
and field example). Documentation comments placed in the body of a method are ignored. Only one
documentation comment per declaration statement is recognized by the Javadoc tool.
A common mistake is to put an import statement between the class comment and the class declaration.
Avoid this, as javadoc will ignore the class comment.
/**
* This is the class comment for the class Whatever.
*/
import com.sun; // MISTAKE - Important not to put statement here
public class Whatever {
}
A comment is a description followed by tags - The description begins after the starting delimiter /**
and continues until the tag section. The tag section starts with the first character @ that begins a
line (ignoring leading asterisks and white space). It is possible to have a comment with only tags
and no description. The description cannot continue after the tag section begins. The argument to a
tag can span multiple lines. There can be any number of tags - some types of tags can be repeated
while others cannot. This @see starts the tag section:
/**
* This is a doc comment.
* @see java.lang.Object
*/
Standard and in-line tags - A tag is a special keyword within a doc comment that the Javadoc tool can
process. The Javadoc tool has standalone tags, which appear as @tag, and in-line tags, which appear
within braces, as {@tag}. To be interpreted, a standalone tag must appear at the beginning of a
line, ignoring leading asterisks, white space and comment separator (/**). This means you can use
the @ character elsewhere in the text and it will not be interpreted as the start of a tag. If you
want to start a line with the @ character and not have it be interpreted, use the HTML entity @.
Each standalone tag has associated text, which includes any text following the tag up to, but not
including, either the next tag, or the end of the doc comment. This associated text can span multiple
lines. An in-line tag is allowed and interpreted anywhere that text is allowed. The following exam-ple example
ple contains the standalone tag @deprecated and in-line tag {@link}.
/**
* @deprecated As of JDk 1.1, replaced by {@link #setBounds(int,int,int,int)}
*/
Comments are written in HTML - The text must be written in HTML, in that they should use HTML enti-ties entities
ties and HTML tags. You can use whichever version of HTML your browser supports; we have written the
standard doclet to generate HTML 3.2-compliant code elsewhere (outside of the documentation comments)
with the inclusion of cascading style sheets and frames. (We preface each generated file with "HTML
4.0" because of the frame sets.)
For example, entities for the less-than (<) and greater-than (>) symbols should be written < and
>. Likewise, the ampersand (&) should be written &. The bold HTML tag <b> is shown in the
following example:
/**
* This is a <b>doc</b> comment.
* @see java.lang.Object
*/
Leading asterisks - When javadoc parses a doc comment, leading asterisk (*) characters on each line
are discarded; blanks and tabs preceding the initial asterisk (*) characters are also discarded. If
you omit the leading asterisk on a line, all leading white space is removed. Therefore, you should
not omit leading asterisks if you want leading white space to be kept, such as when indenting sample
code with the <pre> tag.
First sentence - The first sentence of each doc comment should be a summary sentence, containing a
concise but complete description of the declared entity. This sentence ends at the first period that
is followed by a blank, tab, or line terminator, or at the first standalone tag. The Javadoc tool
copies this first sentence to the member summary at the top of the HTML page.
Declaration with multiple fields - Java allows declaring multiple fields in a single statement, but
this statement can have only one documentation comment, which is copied for all fields. Therefore,
if you want individual documentation comments for each field, you must declare each field in a sepa-rate separate
rate statement. For example, the following documentation comment doesn't make sense when written as
a single declaration and would be better handled as two declarations:
/**
* The horizontal and vertical distances of point (x,y)
*/
public int x, y; // Avoid this
The Javadoc tool generates the following documentation from the above code:
public int x
The horizontal and vertical distances of point (x,y).
public int y
The horizontal and vertical distances of point (x,y).
Use header tags carefully - When writing documentation comments for members, it is best not to use
HTML heading tags such as <H1> and <H2>, because the Javadoc tool creates an entire structured docu-ment document
ment and these structural tags can interfere with the formatting of the generated document. However,
it is fine to use these headings in class and package comments to provide your own structure.
Automatic Reuse of Method Comments
The Javadoc tool has the ability to automatically reuse or "inherit" method comments in classes and
interfaces. When a description, or @return, @param, @see or @throws tag is missing from a method com-ment, comment,
ment, the Javadoc tool instead copies the corresponding description or tag comment from the method it
overrides or implements (if any), according to the algorithm below.
More specifically, when a @param tag for a particular parameter is missing, then the comment for that
parameter is copied. When an @throws tag for a particular exception is missing, the @throws tag is
copied only if that exception is declared.
This behavior contrasts with version 1.3 and earlier, where the presence of any description or tag
would prevent all comments from being inherited.
Also of interest, is the inline tag {@inheritDoc} is present in a description or any tag, the corre-sponding corresponding
sponding description or tag is copied at that spot.
The overridden method must be a member of a documented class, and not an external referenced class
for the doc comment to actually be available to copy.
Inheriting of comments occurs in three cases:
When a method in a class overrides a method in a superclass
When a method in an interface overrides a method in a superinterface
When a method in a class implements a method in an interface
In the first two cases, for method overrides, the Javadoc tool generates a subheading "Overrides" in
the documentation for the overriding method, with a link to the method it is overriding.
In the third case, when a method in a given class implements a method in an interface, the Javadoc
tool generates a subheading "Specified by" in the documentation for the overriding method, with a
link to the method it is implementing.
Algorithm for Inheriting Method Descriptions If a method does not have a doc comment, the Javadoc
tool searches for an applicable comment using the following algorithm, which is designed to find the
most specific applicable doc comment, giving preference to interfaces over superclasses:
1. Look in each directly implemented (or extended) interface in the order they appear following the
word implements (or extends) in the method declaration. Use the first doc comment found for this
method.
2. If step 1 failed to find a doc comment, recursively apply this entire algorithm to each directly
implemented (or extended) interface, in the same order they were examined in step 1.
3. If step 2 failed to find a doc comment and this is
a class other than Object (not an interface):
a. If the superclass has a doc comment for this method, use it.
b. If step 3a failed to find a doc comment, recursively apply this
entire algorithm to the superclass.
javadoc Tags
The Javadoc tool parses special tags when they are embedded within a Java doc comment. These doc
tags enable you to autogenerate a complete, well-formatted API from your source code. The tags start
with an "at" sign (@) and are case-sensitive - they must be typed with the uppercase and lowercase
letters as shown. A tag must start at the beginning of a line (after any leading spaces and an
optional asterisk) or it is treated as normal text. By convention, tags with the same name are
grouped together. For example, put all @see tags together.
Tags come in two types:
Standalone tags - Can be placed only in the tag section that follows the desription. There tags are
not set off with curly braces: @tag.
Inline tags - Can be placed anywhere in the comments description or in the comments for standalone
tags. Inline tags are set off with curly braces:{@tag}.
For information about tags we might introduce in future releases, see Proposed Tags.
The current tags are:
+--------------+-------------+
| Tag | Introduced |
| | in JDK |
+--------------+-------------+
|@author | 1.0 |
|{@code} | 1.5 |
|{@docRoot} | 1.3 |
|@deprecated | 1.0 |
|@exception | 1.0 |
|{@inheritDoc} | 1.4 |
|{@link} | 1.2 |
|{@linkplain} | 1.4 |
|{@literal} | 1.5 |
|@param | 1.0 |
|@return | 1.0 |
|@see | 1.0 |
|@serial | 1.2 |
|@serialData | 1.2 |
|@serialField | 1.2 |
|@since | 1.1 |
|@throws | 1.2 |
|{@value} | 1.4 |
|@version | 1.0 |
+--------------+-------------+
For custom tags, see the -tag option.
@author name-text
Adds an "Author" entry with the specified name-text to the generated docs when the -author
option is used. A doc comment may contain multiple @author tags. You can specify one name
per @author tag or multiple names per tag. In the former case, the Javadoc tool inserts a
comma (,) and space between names. In the latter case, the entire text is simply copied to
the generated document without being parsed. Therefore, use multiple names per line if you
want a localized name separator other than a comma.
@deprecated deprecated-text
Adds a comment indicating that this API should no longer be used (even though it might con-tinue continue
tinue to work). javadoc moves the deprecated-text ahead of the description, placing it in
italics and preceding it with a bold warning: "Deprecated".
The first sentence of deprecated-text should at least tell the user when the API was depre-cated deprecated
cated and what to use as a replacement. javadoc copies just the first sentence to the summary
section and index. Subsequent sentences can also explain why it has been deprecated. You
should include a {@link} tag (for javadoc 1.2 or later) that points to the replacement API:
For javadoc 1.2, use a {@link} tag. This creates the link in-line, where you want it. For
example:
/**
* @deprecated As of JDK 1.1, replaced by
* {@link #setBounds(int,int,int,int)}
*/
For javadoc 1.1, the standard format is to create a @see tag (which cannot be in-line) for
each @deprecated tag.
For more about deprecation, see the @deprecated tag.
{@code text}
Equivalent to <code>{@literal}</code> .
Displays text in code font without interpreting the text as HTML markup or nested javadoc tags. This
enables you to use regular angle brackets ( < and > ) instead of the HTML entities ( < and > )
in doc comments, such as in parameter types ( <Object> ), inequalities ( 3 < 4 ), or arrows ( <- ).
For example, the doc comment text:
{@code A<B>C}
displays in the generated HTML page unchanged as:
A<B>C
The noteworthy point is that the <B> is not interpreted as boldand is in code font.
If you want the same functionality without the code font, use {@literal}.
{@docRoot}
Represents the relative path to the generated document's (destination) root directory from any
generated page. It is useful when you want to include a file, such as a copyright page or
company logo, that you want to reference from all generated pages. Linking to the copyright
page from the bottom of each page is common.
This {@docRoot} tag can be used both on the command line and in a doc comment:
1. On the command line, where the header/footer/bottom are defined:
javadoc -bottom '<a href="{@docRoot}/copyright.html">Copyright</a>'
NOTE - When using {@docRoot} this way in a make file, some makefile programs require special
escaping for the brace {} characters. For example, the Inprise MAKE version 5.2 running on
Windows requires double braces: {{@docRoot}}. It also requires double (rather than single)
quotes to enclose arguments to options such as -bottom (with the quotes around the href argu-ment argument
ment omitted).
2. In a doc comment:
/**
* See the <a href="{@docRoot}/copyright.html">Copyright</a>.
*/
The reason this tag is needed is because the generated docs are in hierarchical directories,
as deep as the number of subpackages. This expression:
<a href="{@docRoot}/copyright.html">
would resolve to:
<a href="../../copyright.html"> ... for java/lang/Object.java
and
<a href="../../../copyright.html"> ... for java/lang/ref/Reference.java
@exception class-name description
The @exception tag is a synonym for @throws.
{@inheritDoc}
Inherits documentation from the nearest superclass into the current doc comment. This allows
comments to be abstracted up the inheritance tree, and enables developers to write around the
copied text. Also see inheriting comments.
This tag can be placed in two positions:
In the comment body (before the first standalone tag), where it will copy the entire comment
body from its superclass.
In the text argument of a standalone tag, where it will copy the text of the tag from its
superclass.
{@link " package.class#member label" }
Inserts an in-line link with visible text label that points to the documentation for the spec-ified specified
ified package, class or member name of a referenced class.
This tag is very similar to @see - both require the same references and accept exactly the
same syntax for package.class#member and label. The main difference is that {@link} generates
an in-line link rather than placing the link in the "See Also" section. Also, the {@link} tag
begins and ends with curly braces to separate it from the rest of the in-line text. If you
need to use "}" inside the label, use the HTML entity notation }
There is no limit to the number of {@link} tags allowed in a sentence. You can use this tag
in the description part of a documentation comment or in the text portion of any tag (such as
@deprecated, @return, or @param).
For example, here is a comment that refers to the getComponentAt(int, int) method:
Use the {@link #getComponentAt(int, int) getComponentAt} method.
>From this, the standard doclet would generate the following HTML (assuming it refers to
another class in the same package):
Use the
<a href="Component.html#getComponentAt(int, int)">\
getComponentAt</a>method.
which appears on the web page as:
Use the getComponentAt method.
You can extend {@link} to link to classes not being documented by using the -link otion.
{@linkplain " package.class#member label"}
Indentical to {@link}, except the link's label is displayed in plain text than code font. Use-ful Useful
ful when the label is plain text. Example:
Refer to {@linkplain add() the overridden method}.
This would display as
Refer to the overridden method.
{@literal text}
Displays text without interpreting the text as HTML markup or nested javadoc tags. This
enables you to use regular angle brackets ( < and > ) instead of the HTML entities ( < and
> ) in doc comments, such as in parameter types ( <Object> ), inequalities ( 3 < 4 ), or
arrows ( <- ). For example, the doc comment text:
{@literal A<B>C}
displays unchanged in the generated HTML page in your browser, as:
A<B>C
The noteworthy point is that the <B> is not interpreted as bold(and it is not in code font).
If you want the same functionality but with the text in code font, use {@code} .
@param parameter-name description
Adds a parameter with the specified parameter-name followed by the specified description to
the "Parameters" section. When writing the doc comment, you may continue the description onto
multiple lines. This tag is valid only in a doc comment for a method, constructor or class.
The parameter-name can be the name of a parameter in a method or constructor, or the name of a type
parameter of a class. Use angle brackets around this parametername to specify the use of a type
parameter, such as:
,nf /** * @param <E> Type of element stored in a list */ public interface List<E> extends Col-lection<E> Collection<E>
lection<E> { }
For more details, see writing @param tags.
@return description
Adds a "Returns" section with the description text. This text should describe the return type
and permissible range of values.
@see <a href='URL#value'>label</a>
Adds a link as defined by URL#value. The URL#value is a relative or absolute URL. The Javadoc
tool distinguishes this from other cases by looking for a less-than symbol (<) as the first
character. For example:
@see <a href="spec.html#section">Java Spec</a>
This generated a link such as:
See Also: "Java Spec"
@see string
Adds a text entry for string. No link is generated. The string is a book or other reference
to information not available by URL. The Javadoc tool distinguishes this from the previous
cases by looking for a double-quote (") as the first character. For example:
@see "The Java Programming Language"
This generates text such as:
See Also:
"The Java Programming Language"
@see <a href="URL#value">label</a>
Adds a link as defined by URL#value. The URL#value is a relative or absolute URL. The Javadoc
tool distinguishes this from other cases by looking for a less-than symbol (<) as the first
character. For example:
@see <a href="spec.html#section">Java Spec</a>
This generates a link such as:
See Also:
Java Spec
@see package.class#member label
Adds a link, with visible text label, that points to the documentation for the specified name
in the Java Language that is referenced. The label is optional; if omitted, the name appears
instead as the visible text, suitably shortened (see How a Name Is Displayed). Use the label
when you want the visible text to be abbreviated or different from the name.
In version 1.2, just the name but not the label would automatically appear in <code> HTML
tags. Starting with 1.2.2, the <code> is always included around the visible text, whether or
not a label is used.
package.class#member is any valid name in the Java Language that is referenced (package,
class, interface, constructor, method, or field name), except that you replace the dot ahead
of the member name with a hash character (#). If this name is in the documented classes,
the Javadoc tool will automatically create a link to it. To create links to external refer-enced referenced
enced classes, use the -link option. Use either of the other two @see forms for referring
to documentation of a name that does not belong to a referenced class. This argument is
described at greater length below under Specifying a Name.
label is optional text that is visible as the link's label. The label can contain white
space. If a label is omitted, then package.class.member will appear, suitably shortened
relative to the current class and package (see How a Name Is Displayed).
A space is the delimiter between package.class#member and label. A space inside parentheses
does not indicate the start of a label, so spaces can be used between parameters in a
method.
Example - In this example, an @see tag (in the Character class) refers to the equals method in
the String class. The tag includes both arguments, that is, the name "String#equals(Object)"
and the label "equals":
/**
* @see String#equals(Object) equals
*/
The standard doclet produces HTML something like this:
<dl>
<dt><b>See Also:</b>
<dd><a href="../../java/lang/String#equals\
(java.lang.Object)"><code>equals</code></a>
</dl>
The above looks something like this in a browser, where the label is the visible link text:
See Also:
equals
Specifying a Name - This package.class#member name can be either fully qualified, such as
java.lang.String#toUpperCase(), or not, such as String#toUpperCase() or #toUpperCase(). If
less than fully-qualified, the Javadoc tool uses the normal Java compiler search order to find
it, further described below in Search order for @see. The name can contain whitespace within
parentheses, such as between method arguments.
Of course the advantage to providing shorter, "partially-qualified" names is that they are
less to type and less clutter in the source code. The following table shows the different
forms of the name, where Class can be a class or interface, Type can be a class, interface,
array, or primitive, and method can be a method or constructor.
+-----------------------------------------------------------+
| Typical forms for @see package.class#member |
+-----------------------------------------------------------+
|Referencing a member of the current class |
|@see #field |
|@see #method(Type, Type,...) |
|@see #method(Type argname, Type argname,...) |
|Referencing another class in the current or imported |
|packages |
|@see Class#field |
|@see Class#method(Type, Type,...) |
|@see Class#method(Type argname, Type argname,...) |
|@see Class |
|Referencing another package (fully qualified) |
|@see package.Class#field |
|@see package.Class#method(Type, Type,...) |
|@see package.Class#method(Type argname, Type argname,...) |
|@see package.Class |
|@see package |
+-----------------------------------------------------------+
The following notes apply to the above table:
The first set of forms (with no class or package) will cause the Javadoc tool to search only
through the current class's hierarchy. It will find a member of the current class or inter-face, interface,
face, one of its superclasses or superinterfaces, or one of its enclosing classes or inter-faces interfaces
faces (search steps 1-3). It will not search the rest of the current package or other pack-ages packages
ages (search steps 4-5).
If any method or constructor is entered as a name with no parentheses, such as getValue, and
if no field with the same name exists, the Javadoc tool will correctly create a link to it,
but will print a warning message reminding you to add the parentheses and arguments. If
this method is overloaded, the Javadoc tool links to the first method that its search
encounters, which is unspecified.
Nested classes must be specified as outer.inner, not only inner, for all forms.
As stated, the hash character (#), rather than a dot (.), separates a member from its class.
This enables the Javadoc tool to resolve ambiguities, since the dot also separates classes,
nested classes, packages, and subpackages. However, the Javadoc tool is generally lenient
and will properly parse a dot if you know there is no ambiguity, though it will print a
warning.
Search Order for @see: The Javadoc tool will process an @see tag that appears in a source file
(.java), package file (package.html), or overview file (overview.html). In the latter two
files, you must fully qualify the name you supply with @see. In a source file, you can spec-ify specify
ify a name that is fully qualified or partially qualified.
When the Javadoc tool encounters an @see tag in a .java file that is not fully qualified, it
searches for the specified name in the same order as the Java compiler would (except the
Javadoc tool will not detect certain namespace ambiguities, since it assumes the source code
is free of these errors). This search order is formally defined in Chapter 6, "Names" of the
Java Language Specification, Second Edition. The Javadoc tool searches for that name through
all related and imported classes and packages. In particular, it searches in this order:
1. The current class or interface
2. Any enclosing classes and interfaces, searching closest first
3. Any superclasses and superinterfaces, searching closest first
4. The current package
5. Any imported packages, classes and interfaces, searching in the order of the import state-ment statement
ment
The Javadoc tool continues to search recursively through steps 1-3 for each class it encoun-ters encounters
ters until it finds a match. That is, after it searches through the current class and its
enclosing class E, it searches through E's superclasses before E's enclosing classes. In
steps 4 and 5, the Javadoc tool does not search classes or interfaces within a package in any
specified order (that order depends on the particular compiler). In step 5, the Javadoc tool
will look in java.lang,sincethatisautomatically imported by all programs.
The Javadoc tool won't necessarily look in subclasses, nor will it look in other packages even
if their documentation is being generated in the same run. For example, if the @see tag is in
java.awt.event.KeyEvent class and refers to a name in the java.awt package, javadoc will not
look in that package unless that class imports it.
How a Name is Displayed - If label is omitted, then package.class.member will appear. In gen-eral, general,
eral, it will be suitably shortened relative to the current class and package. By "short-ened", "shortened",
ened", we mean the Javadoc tool will display only the minimum name necessary. For example, if
the String.toUpperCase() method contains references to a member of the same class and to a
member of a different class, the class name will be displayed only in the latter case:
Type Example Displays As
of
Ref-erence Reference
erence
@see tag @see toLowerCase()
refers String#toLowerCase() (omits the class name)
to
member
of
the
same
class
@see @see Character.toLowerCase(char)
tag Character#toLowerCase(char) (includes the class name)
refers
to
member
of a
differ-ent different
ent
class
Examples of @see: The comment to the right shows how the name would be displayed if the @see
tag is in a class in another package, such as java.applet.Applet:
Example See also:
@see java.lang.String // String
@see java.lang.String The String class // The String class
@see String // String
@see String#equals(Object) // String.equals(Object)
@see String#equals // String.equals\
(java.lang.Object)
@see java.lang.Object#wait(long) // java.lang.Object.\
wait(long)
@see Character#MAX_RADIX // Character.MAX_RADIX
@see <a href="spec.html">Java Spec</a> // Java Spec
@see "The Java Programming Language" // "The Java Programming \
Language"
You can extend @see to link to classes not being documented
by using the -link option.
@since since-text
Adds a "Since" heading with the specified since-text to the generated documentation. The text
has no special internal structure. This tag means that this change or feature has existed
since the software release specified by the since-text. For example:
@since 1.4
For source code in the Java platform, this tag indicated the version of the Java platform API speci-fication specification
fication (not necessarily when it was added to the reference implementation).
@serial field-description|include|exclude
Used in the doc comment for a default serializable field.
An optional field-description augments the doc comment for the field. The combined descrip-tion description
tion must explain the meaning of the field and list the acceptable values. If needed, the
description can span multiple lines. The standard doclet adds this information to the serial-ized serialized
ized form page.
The include and exclude arguments identify whether a class or package should be included or
excluded from the serialized form page. They work as follows:
A public or protected class that implements
Serializable is included unless the class (or its package) is marked @serial exclude.
A private or package-private class that implements
Serializable is excluded unless that class (or its package) is marked @serial include.
Examples: The javax.swing package is marked @serial exclude (in package.html). The public
class java.sercurity.BasicPermission is marked @serial exclude. The package-private class
java.util.PropertyPermissionCollection is marked @serial include.
The tag @serial at a class level overrides @serial at a package level.
For more information about how to use these tags, along with an example, see "Documenting
Serializable Fields and Data for a Class," Section 1.6 of the Java Object Serialization Speci-fication. Specification.
fication. Also see the "Serialization FAQ," which covers the questions, "Why do I see javadoc
warnings stating that I am missing @serial tags? for private fields if I am not running
javadoc with the -private switch?"
@serialField field-name field-type field-description
Documents an ObjectStreamField component of a Serializable class's serialPersistentFields mem-ber. member.
ber. One @serialField tag should be used for each ObjectStreamField component.
@serialData data-description
The data-description documents the types and order of data in the serialized form. Specifi-cally, Specifically,
cally, this data includes the optional data written by the writeObject method and all data
(including base classes) written by the Externalizable.writeExternal method.
The @serialData tag can be used in the doc comment for the writeObject, readObject, writeEx-ternal, writeExternal,
ternal, and readExternal methods.
@throws class-name description
The @throws and @exception tags are synonyms. Adds a "Throws" subheading to the generated
documentation, with the class-name and description text. The class-name is the name of the
exception that may be thrown by the method. If this class is not fully specified, the Javadoc
tool uses the search order to look up this class. Multiple @throws tags can beused in a given
doc comment for the same or different exceptions.
To ensure that all checked exceptions are documented, if a @throws tag does not exist for an excep-tion exception
tion inthe throws clause, the Javadoc tool automatically adds that exception to the HTML output (with
no description) as if it were documented with @throws tag.
The @throws documentation is copied from an overridden method to a subclass only when the exception
is explicitly declared in the overridden method. The same is true for copying from an interfacemethod
to an implementing method. You can use {@inheritDoc} to force@throws to inherit documentation.
For more details, see Writing @throws tags.
{@value package.class#field}
When {@value} is used (without any argument) in the doc command of a static field, it displays
the value of that constant:
/**
* The value of this constant is {@value}.
*/
public static final String SCRIPT_START = "<script>"
When used with argument package.class#field in any doc comment, it displays the value of the speci-fied specified
fied constant:
/**
* Evaluates the script starting with {@value #SCRIPT_START}.
*/
public String evalScript(String script) {
}
The argument package.class#field takes a form identical to that of the @see argument, except that the
member must be a static field.
These values of these constants are also displayed on the Constant Field Values page.
@version version-text
Adds a "Version" subheading with the specified version-text to the generated docs when the
-version option is used. The text has no special internal structure. A doc comment may con-tain contain
tain at most one @version tag. Version normally refers to the version of the software (such
as the Java 2 SDK) that contains this class or member.
Where Tags Can Be Used
The following sections describe where the tags can be used. Notice that these four tags can be used
in all doc comments: @see, @link, @since, @deprecated.
Overview Documentation Tags
Overview tags are tags that can appear in the documentation comment for the overview page, which
resides in the source file typically named (overview.html). Like any other documentation comments,
these tags must appear after the description.
NOTE: The {@link} tag has a bug in overview documents in version 1.2. Text appears properly but has
no link. The {@docRoot} tag does not currently work in overview documents.
+--------------+
|Overview Tags |
+--------------+
|@see |
|@since |
|@author |
|@version |
|{@link} |
|{@linkplain} |
|{@docRoot} |
+--------------+
Package Documentation Tags
Package tags are tags that can appear in the documentation comment for a package (which resides in
the source file named package.html). The @serial tag can only be used here with the include or
exclude argument.
+-------------+
|Package Tags |
+-------------+
|@see |
|@since |
|@deprecated |
|@serial |
|@author |
|{@link} |
|{@linkplain} |
|{@docRoot} |
+-------------+
Class and Interface Documentation Tags
The following are tags that can appear in the documentation comment for a class or interface. The
@serial tag can only be used here with the include or exclude argument.
+---------------------+
|Class/Interface Tags |
+---------------------+
|@see |
|@since |
|@deprecated |
|@serial |
|@author |
|@version |
|{@link} |
|{@linkplain} |
|{@docRoot} |
+---------------------+
An example of a class comment:
/**
* A class representing a window on the screen.
* For example:
* <pre>
* Window win = new Window(parent);
* win.show();
* </pre>
*
* @author Sami Shaio
* @version 1.8, 06/24/04
* @see java.awt.BaseWindow
* @see java.awt.Button
*/
class Window extends BaseWindow {
}
Field Documentation Tags
The following are the tags that can appear in the documentation comment for a field.
+-------------+
| Field Tags |
+-------------+
|@see |
|@since |
|@deprecated |
|@serial |
|@serialField |
|{@link} |
|{@linkplain} |
|{@docRoot} |
|{@value} |
+-------------+
An example of a field comment:
/**
* The X-coordinate of the component.
*
* @see #getLocation()
*/
int x = 1263732;
Constructor and Method Documentation Tags
The following are the tags that can appear in the documentation comment for a constructor or method,
except for {@inheritDoc}, which cannot appear in a constructor.
+------------------------+
|Method/Constructor Tags |
+------------------------+
|@see |
|@since |
|@deprecated |
|@param |
|@return |
|@throws and @exception |
|@serialData |
|{@link} |
|{@linkplain} |
|{@inheritDoc} |
|{@docRoot} |
+------------------------+
An example of a method doc comment:
/**
* Returns the character at the specified index. An index
* ranges from <code>0</code> to <code>length() - 1</code>.
*
* @param index the index of the desired character.
* @return the desired character.
* @exception StringIndexOutOfRangeException
* if the index is not in the range <code>0</code>
* to <code>length()-1</code>.
* @see java.lang.Character#charValue()
*/
public char charAt(int index) {
}
OPTIONS
The Javadoc tool uses doclets to determine its output. The Javadoc tool uses the default standard
doclet unless a custom doclet is specified with the -doclet option. The Javadoc tool provides a set
of command-line options that can be used with any doclet. These options are described below under
the sub-heading Javadoc Options. The standard doclet provides an additional set of command-line
options that are described below, under the sub-heading Options Provided by the Standard Doclet. All
option names are case-insensitive, though their arguments can be case-sensitive.
The options are:
-1.1 -help -package
-author -helpfile -private
-bootclasspath -J -protected
-bottom -keywords -public
-charset -link -quiet
-classpath -linkoffline -serialwarn
-d -linksource -source
-docencoding -locale -sourcepath
-doclet -nodeprecated -splitindex
-docletpath -nodeprecatedlist -stylesheetfile
-doctitle -nohelp -subpackages
-encoding -noindex -tag
-exclude -nonavbar -taglet
-excludedocfilessubdir -noqualifier -tagletpath
-extdirs -nosince -title
-footer -notimestamp -use
-group -notree -verbose
-header -overview windowtitle
-version
Javadoc Options
-overview path/filename
Specifies that javadoc should retrieve the text for the overview documentation from the
"source" file specified by path/filename and place it on the Overview page (overview-sum-mary.html). (overview-summary.html).
mary.html). The path/filename is relative to the -sourcepath.
While you can use any name you want for filename and place it anywhere you want for path, a
typical thing to do is to name it overview.html and place it in the source tree at the direc-tory directory
tory that contains the topmost package directories. In this location, no path is needed when
documenting packages, since -sourcepath will point to this file. For example, if the source
tree for the java.lang package is /src/classes/java/lang/, then you could place the overview
file at /src/classes/overview.html. See Real World Example.
For information about the file specified by path/filename, see overview comment file.
Notice that the overview page is created only if you pass into javadoc two or more package
names. For further explanation, see HTML Frames.
The title on the overview page is set by -doctitle .
-public
Shows only public classes and members.
-protected
Shows only protected and public classes and members. This is the default.
-package
Shows only package, protected, and public classes and members.
-private
Shows all classes and members.
-help Displays the online help, which lists these javadoc and doclet command line options.
-doclet class
Specifies the class file that starts the doclet used in generating the documentation. Use the
fully-qualified name. This doclet defines the content and formats the output. If the -doclet
option is not used, javadoc uses the standard doclet for generating the default HTML format.
This class must contain the start(Root) method. The path to this starting class is defined by
the -docletpath option.
For example, to call the MIF doclet, use:
-doclet com.sun.tools.doclets.mif.MIFDoclet
-docletpath classpathlist
Specifies the path to the doclet class file (specified with the -doclet option) and any jar
files it depends on. If the starting class file is in a jar file, then this specifies the
path to that jar file, as shown in the example below. You can specify an absolute path or a
path relative to the current directory. If classpath contains multiple paths or jar files,
they should be separated with a colon (:) on Windows. This option is not necessary if the
doclet is already in the search path.
Example of path to jar file that contains the startig doclet class file. Notice the jar file-name filename
name is included.
-docletpath /home/user/mifdoclet/lib/mifdoclet.jar
Example of path to starting doclet class file. Notice the class filename is omitted.
-docletpath /home/user/mifdoclet/classes/com/sun/tools/doclets/mif/
-1.1 This feature has been removed from Javadoc 1.4. There is no replacement for it. This option
created documentation with the appearance and functionality of documentation generated by
Javadoc 1.1 (including never supporting nested classes). If you need this option, use Javadoc
1.2 or 1.3 instead.
-sourcepath sourcepathlist
Specifies the search paths for finding source files (.java) when passing package names or
-subpackages into the javadoc command. The sourcepathlist can contain multiple paths by sepa-rating separating
rating them with a colon (:). The Javadoc tool will search in all subdirectories of the speci-fied specified
fied paths. Note that this option is not only used to located the source files being docu-mented, documented,
mented, but also to find source files that are not being documented but whose comments are
inherited by the source files being documented.
Note that you can use the -sourcepath option only when passing package names into the javadoc
command - it will not locate .java files passed into the javadoc command. (To locate .java
files, cd to that directory or include the path ahead of each file, as shown at Documenting
One or More Classes.) If -sourcepath is omitted, javadoc uses the class path to find the
source files (see -classpath). Therefore, the default -sourcepath is the value of class path.
If -classpath is omitted and you are passing package names into javadoc, it looks in the cur-rent current
rent directory (and subdirectories) for the source files.
Set sourcepathlist to the root directory of the source tree for the package you are document-ing. documenting.
ing. For example, suppose you want to document a package called com.mypackage whose source
files are located at:
/home/user/src/com/mypackage/*.java
In this case, you would specify the source path to /home/user/src, the directory that contains
com/mypackage, and then supply the package name com.mypackage:
example% javadoc -sourcepath /home/user/src/ com.mypackage
This is easy to remember by noticing that if you concatenate the value of the source path and
the package name together and change the dot to a slash "/", you end up with the full path to
the package:
/home/user/src/com/mypackage
To point to two source paths:
example% javadoc -sourcepath /home/user/src/:/home/user2/src com.mypackage
-classpath classpathlist
Specifies the paths where javadoc looks for referenced classes (.class files) - these are the
documented classes plus any classes referenced by those classes. The classpathlist can con-tain contain
tain multiple paths by separating them with a colon (:). The Javadoc tool will search in all
subdirectories of the specified paths. Follow the instructions in class path documentation
for specifying classpathlist.
If -sourcepath is omitted, the Javadoc tool uses -classpath to find the source files as well
as class files (for backward compatibility). Therefore, if you want to search for source and
class files in separate paths, use both -sourcepath and -classpath.
For example, if you want to document com.mypackage, whose source files reside in the directory
/home/user/src/com/mypackage, and if this package relies on a library in /home/user/lib, you
would specify:
example% javadoc -classpath /home/user/lib -sourcepath \
/home/user/src com.mypackage
As with other tools, if you do not specify -classpath, the Javadoc tool uses the CLASSPATH
environment variable, if it is set. If both are not set, the Javadoc tool searches for
classes from the current directory.
For an in-depth description of how the Javadoc tool uses -classpath to find user classes as it
relates to extension classes and bootstrap classes, see How Classes Are Found.
-bootclasspath classpathlist
Specifies the paths where the boot classes reside. These are nominally the Java platform
classes. The bootclasspath is part of the search path the Javadoc tool will use to look up
source and class files. See How Classes Are Found for more details. Separate directories in
classpathlist with colons (:).
-extdirs dirlist
Specifies the directories where extension classes reside. These are any classes that use the
Java Extension mechanism. The extdirs is part of the search path the Javadoc tool will use to
look up source and class files. See -classpath (above) for more details. Separate directo-ries directories
ries in dirlist with colons (:).
-verbose
Provides more detailed messages while javadoc is running. Without the verbose option, mes-sages messages
sages appear for loading the source files, generating the documentation (one message per
source file), and sorting. The verbose option causes the printing of additional messages
specifying the number of milliseconds to parse each java source file.
-quiet Shuts off non-error and non-warning messages, leaving only the warnings and errors appear,
making them easier to view. Also suppresses the version string.
-locale language_country_variant
Important: The -locale option must be placed ahead (to the left) of any options provided by
the standard doclet or any other doclet. Otherwise, the navigation bars will appear in
English. This is the only command-line option that is order-dependent.
Specifies the locale that javadoc uses when generating documentation. The argument is the
name of the locale, as described in java.util.Locale documentation, such as en_US (English,
United States) or en_US_WIN (Windows variant).
Specifying a locale causes javadoc to choose the resource files of that locale for messages
(strings in the navigation bar, headings for lists and tables, help file contents, comments in
stylesheet.css, and so forth). It also specifies the sorting order for lists sorted alphabet-ically, alphabetically,
ically, and the sentence separator to determine the end of the first sentence. It does not
determine the locale of the doc comment text specified in the source files of the documented
classes.
-encoding name
Specifies the source file encoding name, such as EUCJIS/SJIS. If this option is not speci-fied, specified,
fied, the platform default converter is used.
-Jflag Passes flag directly to the runtime system java that runs javadoc. Notice there must be no
space between the J and the flag. For example, if you need to ensure that the system sets
aside 32 megabytes of memory in which to process the generated documentation, then you would
call the -Xmx option of java as follows:
example% javadoc -J-Xmx32m -J-Xms32m com.mypackage
To tell what version of javadoc you are using, call the -version option of java:
example% javadoc -J-version
java version "1.2"
Classic VM (build JDK-1.2-V, green threads, sunwjit)
(The version number of the standard doclet appears in its output stream.)
Options Provided by the Standard Doclet
-d directory
Specifies the destination directory where javadoc saves the generated HTML files. (The "d"
means "destination.") Omitting this option causes the files to be saved to the current direc-tory. directory.
tory. The value directory can be absolute or relative to the current working directory. As
of 1.4, the destination directory is automatically created when javadoc is run.
For example, the following generates the documentation for the com.mypackage package and saves
the results in the /home/user/doc/ directory:
example% javadoc -d /home/user/doc com.mypackage
-use Includes one "Use" page for each documented class and package. The page describes what pack-ages, packages,
ages, classes, methods, constructors, and fields use any API of the given class or package.
Given class C, things that use class C would include subclasses of C, fields declared as C,
methods that return C, and methods and constructors with parameters of type C.
For example, look at what might appear on the "Use" page for String. The getName() method in
the java.awt.Font class returns type String. Therefore, getName() uses String, and you will
find that method on the "Use" page for String.
Note that this documents only uses of the API, not the implementation. If a method uses
String in its implementation but does not take a string as an argument or return a string,
that is not considered a "use" of String.
You can access the generated "Use" page by first going to the class or package, then clicking
on the "Use" link in the navigation bar.
-version
Includes the @version text in the generated docs. This text is omitted by default. To tell
what version of the Javadoc tool you are using, use the -J-version option.
-author
Includes the @author text in the generated docs.
-splitindex
Splits the index file into multiple files, alphabetically, one file per letter, plus a file
for any index entries that start with non-alphabetical characters.
-windowtitle title
Specifies the title to be placed in the HTML <title> tag. This appears in the window title
and in any browser bookmarks (favorite places) that someone creates for this page. This title
should not contain any HTML tags, as the browser cannot properly interpret them. Any internal
quotation marks within title might have to be escaped. If -windowtitle is omitted, the
Javadoc tool uses the value of -doctitle for this option.
example% javadoc -windowtitle "Java 2 Platform" com.mypackage
-doctitle title
Specifies the title to be placed near the top of the overview summary file. The title is
placed as a centered, level-one heading directly beneath the upper navigation bar. The title
may contain HTML tags and white space, though if it does, it must be enclosed in quotes. Any
internal quotation marks within title may have to be escaped.
example% javadoc -doctitle "Java<sup><font size=
TM</font></sup>" com.mypackage
-title title
This option no longer exists. It existed only in Beta versions of Javadoc 1.2. It has been
renamed to -doctitle. This option was renamed to make it clear that it defines the document
title rather than the window title.
-header header
Specifies the header text to be placed at the top of each output file. The header is placed
to the right of the upper navigation bar. header may contain HTML tags and white space,
though if it does, it must be enclosed in quotes. Any internal quotation marks within header
may have to be escaped.
-footer footer
Specifies the footer text to be placed at the bottom of each output file. The footer is
placed to the right of the lower navigation bar. footer may contain HTML tags and white
space, though if it does, it must be enclosed in quotes. Any internal quotation marks within
footer may have to be escaped.
-bottom text
Specifies the text to be placed at the bottom of each output file. The text is placed at the
bottom of the page, below the lower navigation bar. text may contain HTML tags and white
space, though if it does, it must be enclosed in quotes. Any internal quotation marks within
text may have to be escaped.
-link extdocURL
Creates links to existing javadoc-generated documentation of external referenced classes. It
takes one argument.
extdocURL is the absolute or relative URL of the directory containing the external javadoc-generated javadocgenerated
generated documentation you want to link to. Examples are shown below. The package-list file
must be found in this directory (otherwise, use -linkoffline). The Javadoc tool reads the
package names from the package-list file and then links to those packages at that URL. When
the Javadoc tool is run, the extdocURL value is copied literally into the <A HREF> links that
are created. Therefore, extdocURL must be the URL to the directory, not to a file.
You can use an absolute link for extdocURL to enable your docs to link to a document on any
website, or can use a relative link to link only to a relative location. If relative, the
value you pass in should be the relative path from the destination directory (specified with
-d ) to the directory containing the packages being linked to.
When specifying an absolute link you normally use an http: link. However, if you want to link
to a file system that has no web server, you can use a file: link - however, do this only if
everyone wanting to access the generated documentation shares the same file system.
You can specify multiple -link options in a given javadoc run to link to multiple documents.
Choosing between -linkoffline and -link - One or the other option is appropriate when linking
to an API document that is external to the current javadoc run.
Use -link: when using a relative path to the external API document, or when using an absolute
URL to the external API document, if you shell does not allow a program to open a connection
to that URL for reading.
Use -linkoffline : when using an absolute URL to the external API document, if your shell does
not allow a program to open a connection to that URL for reading. This can occur if you are
behind a firewall and the document you want to link to is on the other side.
Example using absolute links to the external docs - Let's say you want to link to the
java.lang, java.io and other Java 2 Platform packages at
http://java.sun.com/j2se/1.4/docs/api The following command generates documentation for the
package com.mypackage with links to the Java 2 Platform packages. The generated documentation
will contain links to the Object class, for example in the class trees. (Other options, such
as -sourcepath and -d , are not shown.)
% javadoc -link http://java.sun.com/j2se/1.4/docs/api com.mypackage
Example using relative links to the external docs - Let's say you have two packages whose docs
are generated in different runs of the Javadoc tool, and those docs are separated by a rela-
tive path. In this example, the packages are com.apipackage, and API, and com.spipackage, an
SPI (Service Provide Interface). YOu want the documentation to reside in docs/api/com/api-
package and docs/spi/com/spipackage. Assuming the API package documentation is already gener-
ated, and that docs is the current directory, you would document the SPI package with links to
the API documentation by running:
% javadoc -d ./spi -link ../api com.spipackage
Notice the -link argument is relative to the destination directory (docs/spi).
Details - The -link option enables you to link to classes referenced to by your code but not
documented in the current javadoc run. For these links to go to valid pages, you must know
where those HTML pages are located, and specify that location with extdocURL . This allows,
for instance, third party documentation to link to java.* documentation on
http://java.sun.com
Omit the -link option for javadoc to create links only to API within the documentation it is
generating in the current run. (Without the -link option, the Javadoc tool does not create
links to documentation for external references, because it does not know if or where that doc-
umentation exists.
This option can create links in several places in the generated documentation.
Another use is for cross-links between sets of packages: Execute javadoc on one set of pack-
ages, then run javadoc again on another set of packages, creating links both ways between both
sets. A third use is as a "hack" to update docs: Execute javadoc on a full set of packages,
then run javadoc again on only the smaller set of changed packages, so that the updated files
can be inserted back into the original set.
Bug Fix for Referenced Classes - In 1.4 the following bug has been fixed:
Link bug in 1.2 and 1.3 - When @see or {@link}
references an excluded class and -link is used,
an <A HREF> hyperlink is created only if the class is referenced
with in an import statement or in a declaration. References
in the body of methods, alone are inadequate. A workaround
was to include an explicit (not wildcard) import
statement for the referenced class.
An @see or {@link} reference with -link is now enough to load the referenced class and enable
a link to it. You can remove any import statements you had added as workarounds, which we had
suggested you comment as follows:
import java.lang.SecurityManager; // workaround to force @see/@link\
hyperlink
Package List - The -link option requires that a file named package-list, which is generated by
the Javadoc tool, exist at the URL you specify with -link. The package-list file is a simple
text file that lists the names of packages documented at that locat |