Component (Java 2 Platform SE v1.4.2

A component is an object having a graphical representation that can be displayed on the screen and that can interact with the user. Examples of components are the buttons, checkboxes, and scrollbars of a typical graphical user interface.

The Component class is the abstract superclass of the nonmenu-related Abstract Window Toolkit components. Class Component can also be extended directly to create a lightweight component. A lightweight component is a component that is not associated with a native opaque window.

Serialization

It is important to note that only AWT listeners which conform to the Serializable protocol will be saved when the object is stored. If an AWT object has listeners that aren't marked serializable, they will be dropped at writeObject time. Developers will need, as always, to consider the implications of making an object serializable. One situation to watch out for is this:

    import java.awt.*;
    import java.awt.event.*;
    import java.io.Serializable;
    
    class MyApp implements ActionListener, Serializable
    {
        BigObjectThatShouldNotBeSerializedWithAButton bigOne;
        Button aButton = new Button();
      
        MyApp()
        {
            // Oops, now aButton has a listener with a reference
            // to bigOne!
            aButton.addActionListener(this);
        }
    
        public void actionPerformed(ActionEvent e)
        {
            System.out.println("Hello There");
        }
    }

In this example, serializing aButton by itself will cause MyApp and everything it refers to to be serialized as well. The problem is that the listener is serializable by coincidence, not by design. To separate the decisions about MyApp and the ActionListener being serializable one can use a nested class, as in the following example:

    import java.awt.*;
    import java.awt.event.*;
    import java.io.Serializable;

    class MyApp java.io.Serializable
    {
         BigObjectThatShouldNotBeSerializedWithAButton bigOne;
         Button aButton = new Button();

         class MyActionListener implements ActionListener
         {
             public void actionPerformed(ActionEvent e)
             {
                 System.out.println("Hello There");
             }
         }
 
         MyApp()
         {
             aButton.addActionListener(new MyActionListener());
         }
    }

Note: For more information on the paint mechanisms utilitized by AWT and Swing, including information on how to write the most efficient painting code, see Painting in AWT and Swing.

See Also:: Serialized Form

Nested Class Summary
`protected class`	`Component.AccessibleAWTComponent` Inner class of Component used to provide default support for accessibility.
`protected class`	`Component.BltBufferStrategy` Inner class for blitting offscreen surfaces to a component.
`protected class`	`Component.FlipBufferStrategy` Inner class for flipping buffers on a component.

Field Summary
`static float`	`BOTTOM_ALIGNMENT` Ease-of-use constant for `getAlignmentY`.
`static float`	`CENTER_ALIGNMENT` Ease-of-use constant for `getAlignmentY` and `getAlignmentX`.
`static float`	`LEFT_ALIGNMENT` Ease-of-use constant for `getAlignmentX`.
`static float`	`RIGHT_ALIGNMENT` Ease-of-use constant for `getAlignmentX`.
`static float`	`TOP_ALIGNMENT` Ease-of-use constant for `getAlignmentY()`.

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary
`protected`	`Component()` Constructs a new component.

Method Summary
`boolean`	`action(Event evt, Object what)` Deprecated. As of JDK version 1.1, should register this component as ActionListener on component which fires action events.
`void`	`add(PopupMenu popup)` Adds the specified popup menu to the component.
`void`	`addComponentListener(ComponentListener l)` Adds the specified component listener to receive component events from this component.
`void`	`addFocusListener(FocusListener l)` Adds the specified focus listener to receive focus events from this component when this component gains input focus.
`void`	`addHierarchyBoundsListener(HierarchyBoundsListener l)` Adds the specified hierarchy bounds listener to receive hierarchy bounds events from this component when the hierarchy to which this container belongs changes.
`void`	`addHierarchyListener(HierarchyListener l)` Adds the specified hierarchy listener to receive hierarchy changed events from this component when the hierarchy to which this container belongs changes.
`void`	`addInputMethodListener(InputMethodListener l)` Adds the specified input method listener to receive input method events from this component.
`void`	`addKeyListener(KeyListener l)` Adds the specified key listener to receive key events from this component.
`void`	`addMouseListener(MouseListener l)` Adds the specified mouse listener to receive mouse events from this component.
`void`	`addMouseMotionListener(MouseMotionListener l)` Adds the specified mouse motion listener to receive mouse motion events from this component.
`void`	`addMouseWheelListener(MouseWheelListener l)` Adds the specified mouse wheel listener to receive mouse wheel events from this component.
`void`	`addNotify()` Makes this `Component` displayable by connecting it to a native screen resource.
`void`	`addPropertyChangeListener(PropertyChangeListener listener)` Adds a PropertyChangeListener to the listener list.
`void`	`addPropertyChangeListener(String propertyName, PropertyChangeListener listener)` Adds a PropertyChangeListener to the listener list for a specific property.
`void`	`applyComponentOrientation(ComponentOrientation orientation)` Sets the `ComponentOrientation` property of this component and all components contained within it.
`boolean`	`areFocusTraversalKeysSet(int id)` Returns whether the Set of focus traversal keys for the given focus traversal operation has been explicitly defined for this Component.
`Rectangle`	`bounds()` Deprecated. As of JDK version 1.1, replaced by `getBounds()`.
`int`	`checkImage(Image image, ImageObserver observer)` Returns the status of the construction of a screen representation of the specified image.
`int`	`checkImage(Image image, int width, int height, ImageObserver observer)` Returns the status of the construction of a screen representation of the specified image.
`protected AWTEvent`	`coalesceEvents(AWTEvent existingEvent, AWTEvent newEvent)` Potentially coalesce an event being posted with an existing event.
`boolean`	`contains(int x, int y)` Checks whether this component "contains" the specified point, where `x` and `y` are defined to be relative to the coordinate system of this component.
`boolean`	`contains(Point p)` Checks whether this component "contains" the specified point, where the point's x and y coordinates are defined to be relative to the coordinate system of this component.
`Image`	`createImage(ImageProducer producer)` Creates an image from the specified image producer.
`Image`	`createImage(int width, int height)` Creates an off-screen drawable image to be used for double buffering.
`VolatileImage`	`createVolatileImage(int width, int height)` Creates a volatile off-screen drawable image to be used for double buffering.
`VolatileImage`	`createVolatileImage(int width, int height, ImageCapabilities caps)` Creates a volatile off-screen drawable image, with the given capabilities.
`void`	`deliverEvent(Event e)` Deprecated. As of JDK version 1.1, replaced by `dispatchEvent(AWTEvent e)`.
`void`	`disable()` Deprecated. As of JDK version 1.1, replaced by `setEnabled(boolean)`.
`protected void`	`disableEvents(long eventsToDisable)` Disables the events defined by the specified event mask parameter from being delivered to this component.
`void`	`dispatchEvent(AWTEvent e)` Dispatches an event to this component or one of its sub components.
`void`	`doLayout()` Prompts the layout manager to lay out this component.
`void`	`enable()` Deprecated. As of JDK version 1.1, replaced by `setEnabled(boolean)`.
`void`	`enable(boolean b)` Deprecated. As of JDK version 1.1, replaced by `setEnabled(boolean)`.
`protected void`	`enableEvents(long eventsToEnable)` Enables the events defined by the specified event mask parameter to be delivered to this component.
`void`	`enableInputMethods(boolean enable)` Enables or disables input method support for this component.
`protected void`	`firePropertyChange(String propertyName, boolean oldValue, boolean newValue)` Support for reporting bound property changes for boolean properties.
`protected void`	`firePropertyChange(String propertyName, int oldValue, int newValue)` Support for reporting bound property changes for integer properties.
`protected void`	`firePropertyChange(String propertyName, Object oldValue, Object newValue)` Support for reporting bound property changes for Object properties.
`AccessibleContext`	`getAccessibleContext()` Gets the `AccessibleContext` associated with this `Component`.
`float`	`getAlignmentX()` Returns the alignment along the x axis.
`float`	`getAlignmentY()` Returns the alignment along the y axis.
`Color`	`getBackground()` Gets the background color of this component.
`Rectangle`	`getBounds()` Gets the bounds of this component in the form of a `Rectangle` object.
`Rectangle`	`getBounds(Rectangle rv)` Stores the bounds of this component into "return value" rv and return rv.
`ColorModel`	`getColorModel()` Gets the instance of `ColorModel` used to display the component on the output device.
`Component`	`getComponentAt(int x, int y)` Determines if this component or one of its immediate subcomponents contains the (x, y) location, and if so, returns the containing component.
`Component`	`getComponentAt(Point p)` Returns the component or subcomponent that contains the specified point.
`ComponentListener[]`	`getComponentListeners()` Returns an array of all the component listeners registered on this component.
`ComponentOrientation`	`getComponentOrientation()` Retrieves the language-sensitive orientation that is to be used to order the elements or text within this component.
`Cursor`	`getCursor()` Gets the cursor set in the component.
`DropTarget`	`getDropTarget()` Gets the `DropTarget` associated with this `Component`.
`Container`	`getFocusCycleRootAncestor()` Returns the Container which is the focus cycle root of this Component's focus traversal cycle.
`FocusListener[]`	`getFocusListeners()` Returns an array of all the focus listeners registered on this component.
`Set`	`getFocusTraversalKeys(int id)` Returns the Set of focus traversal keys for a given traversal operation for this Component.
`boolean`	`getFocusTraversalKeysEnabled()` Returns whether focus traversal keys are enabled for this Component.
`Font`	`getFont()` Gets the font of this component.
`FontMetrics`	`getFontMetrics(Font font)` Gets the font metrics for the specified font.
`Color`	`getForeground()` Gets the foreground color of this component.
`Graphics`	`getGraphics()` Creates a graphics context for this component.
`GraphicsConfiguration`	`getGraphicsConfiguration()` Gets the `GraphicsConfiguration` associated with this `Component`.
`int`	`getHeight()` Returns the current height of this component.
`HierarchyBoundsListener[]`	`getHierarchyBoundsListeners()` Returns an array of all the hierarchy bounds listeners registered on this component.
`HierarchyListener[]`	`getHierarchyListeners()` Returns an array of all the hierarchy listeners registered on this component.
`boolean`	`getIgnoreRepaint()`
`InputContext`	`getInputContext()` Gets the input context used by this component for handling the communication with input methods when text is entered in this component.
`InputMethodListener[]`	`getInputMethodListeners()` Returns an array of all the input method listeners registered on this component.
`InputMethodRequests`	`getInputMethodRequests()` Gets the input method request handler which supports requests from input methods for this component.
`KeyListener[]`	`getKeyListeners()` Returns an array of all the key listeners registered on this component.
`EventListener[]`	`getListeners(Class listenerType)` Returns an array of all the objects currently registered as `FooListener`s upon this `Component`.
`Locale`	`getLocale()` Gets the locale of this component.
`Point`	`getLocation()` Gets the location of this component in the form of a point specifying the component's top-left corner.
`Point`	`getLocation(Point rv)` Stores the x,y origin of this component into "return value" rv and return rv.
`Point`	`getLocationOnScreen()` Gets the location of this component in the form of a point specifying the component's top-left corner in the screen's coordinate space.
`Dimension`	`getMaximumSize()` Gets the maximum size of this component.
`Dimension`	`getMinimumSize()` Gets the mininimum size of this component.
`MouseListener[]`	`getMouseListeners()` Returns an array of all the mouse listeners registered on this component.
`MouseMotionListener[]`	`getMouseMotionListeners()` Returns an array of all the mouse motion listeners registered on this component.
`MouseWheelListener[]`	`getMouseWheelListeners()` Returns an array of all the mouse wheel listeners registered on this component.
`String`	`getName()` Gets the name of the component.
`Container`	`getParent()` Gets the parent of this component.
`java.awt.peer.ComponentPeer`	`getPeer()` Deprecated. As of JDK version 1.1, programs should not directly manipulate peers; replaced by `boolean isDisplayable()`.
`Dimension`	`getPreferredSize()` Gets the preferred size of this component.
`PropertyChangeListener[]`	`getPropertyChangeListeners()` Returns an array of all the property change listeners registered on this component.
`PropertyChangeListener[]`	`getPropertyChangeListeners(String propertyName)` Returns an array of all the listeners which have been associated with the named property.
`Dimension`	`getSize()` Returns the size of this component in the form of a `Dimension` object.
`Dimension`	`getSize(Dimension rv)` Stores the width/height of this component into "return value" rv and return rv.
`Toolkit`	`getToolkit()` Gets the toolkit of this component.
`Object`	`getTreeLock()` Gets this component's locking object (the object that owns the thread sychronization monitor) for AWT component-tree and layout operations.
`int`	`getWidth()` Returns the current width of this component.
`int`	`getX()` Returns the current x coordinate of the components origin.
`int`	`getY()` Returns the current y coordinate of the components origin.
`boolean`	`gotFocus(Event evt, Object what)` Deprecated. As of JDK version 1.1, replaced by processFocusEvent(FocusEvent).
`boolean`	`handleEvent(Event evt)` Deprecated. As of JDK version 1.1 replaced by processEvent(AWTEvent).
`boolean`	`hasFocus()` Returns `true` if this `Component` is the focus owner.
`void`	`hide()` Deprecated. As of JDK version 1.1, replaced by `setVisible(boolean)`.
`boolean`	`imageUpdate(Image img, int infoflags, int x, int y, int w, int h)` Repaints the component when the image has changed.
`boolean`	`inside(int x, int y)` Deprecated. As of JDK version 1.1, replaced by contains(int, int).
`void`	`invalidate()` Invalidates this component.
`boolean`	`isBackgroundSet()` Returns whether the background color has been explicitly set for this Component.
`boolean`	`isCursorSet()` Returns whether the cursor has been explicitly set for this Component.
`boolean`	`isDisplayable()` Determines whether this component is displayable.
`boolean`	`isDoubleBuffered()` Returns true if this component is painted to an offscreen image ("buffer") that's copied to the screen later.
`boolean`	`isEnabled()` Determines whether this component is enabled.
`boolean`	`isFocusable()` Returns whether this Component can be focused.
`boolean`	`isFocusCycleRoot(Container container)` Returns whether the specified Container is the focus cycle root of this Component's focus traversal cycle.
`boolean`	`isFocusOwner()` Returns `true` if this `Component` is the focus owner.
`boolean`	`isFocusTraversable()` Deprecated. As of 1.4, replaced by `isFocusable()`.
`boolean`	`isFontSet()` Returns whether the font has been explicitly set for this Component.
`boolean`	`isForegroundSet()` Returns whether the foreground color has been explicitly set for this Component.
`boolean`	`isLightweight()` A lightweight component doesn't have a native toolkit peer.
`boolean`	`isOpaque()` Returns true if this component is completely opaque, returns false by default.
`boolean`	`isShowing()` Determines whether this component is showing on screen.
`boolean`	`isValid()` Determines whether this component is valid.
`boolean`	`isVisible()` Determines whether this component should be visible when its parent is visible.
`boolean`	`keyDown(Event evt, int key)` Deprecated. As of JDK version 1.1, replaced by processKeyEvent(KeyEvent).
`boolean`	`keyUp(Event evt, int key)` Deprecated. As of JDK version 1.1, replaced by processKeyEvent(KeyEvent).
`void`	`layout()` Deprecated. As of JDK version 1.1, replaced by `doLayout()`.
`void`	`list()` Prints a listing of this component to the standard system output stream `System.out`.
`void`	`list(PrintStream out)` Prints a listing of this component to the specified output stream.
`void`	`list(PrintStream out, int indent)` Prints out a list, starting at the specified indentation, to the specified print stream.
`void`	`list(PrintWriter out)` Prints a listing to the specified print writer.
`void`	`list(PrintWriter out, int indent)` Prints out a list, starting at the specified indentation, to the specified print writer.
`Component`	`locate(int x, int y)` Deprecated. As of JDK version 1.1, replaced by getComponentAt(int, int).
`Point`	`location()` Deprecated. As of JDK version 1.1, replaced by `getLocation()`.
`boolean`	`lostFocus(Event evt, Object what)` Deprecated. As of JDK version 1.1, replaced by processFocusEvent(FocusEvent).
`Dimension`	`minimumSize()` Deprecated. As of JDK version 1.1, replaced by `getMinimumSize()`.
`boolean`	`mouseDown(Event evt, int x, int y)` Deprecated. As of JDK version 1.1, replaced by processMouseEvent(MouseEvent).
`boolean`	`mouseDrag(Event evt, int x, int y)` Deprecated. As of JDK version 1.1, replaced by processMouseMotionEvent(MouseEvent).
`boolean`	`mouseEnter(Event evt, int x, int y)` Deprecated. As of JDK version 1.1, replaced by processMouseEvent(MouseEvent).
`boolean`	`mouseExit(Event evt, int x, int y)` Deprecated. As of JDK version 1.1, replaced by processMouseEvent(MouseEvent).
`boolean`	`mouseMove(Event evt, int x, int y)` Deprecated. As of JDK version 1.1, replaced by processMouseMotionEvent(MouseEvent).
`boolean`	`mouseUp(Event evt, int x, int y)` Deprecated. As of JDK version 1.1, replaced by processMouseEvent(MouseEvent).
`void`	`move(int x, int y)` Deprecated. As of JDK version 1.1, replaced by `setLocation(int, int)`.
`void`	`nextFocus()` Deprecated. As of JDK version 1.1, replaced by transferFocus().
`void`	`paint(Graphics g)` Paints this component.
`void`	`paintAll(Graphics g)` Paints this component and all of its subcomponents.
`protected String`	`paramString()` Returns a string representing the state of this component.
`boolean`	`postEvent(Event e)` Deprecated. As of JDK version 1.1, replaced by dispatchEvent(AWTEvent).
`Dimension`	`preferredSize()` Deprecated. As of JDK version 1.1, replaced by `getPreferredSize()`.
`boolean`	`prepareImage(Image image, ImageObserver observer)` Prepares an image for rendering on this component.
`boolean`	`prepareImage(Image image, int width, int height, ImageObserver observer)` Prepares an image for rendering on this component at the specified width and height.
`void`	`print(Graphics g)` Prints this component.
`void`	`printAll(Graphics g)` Prints this component and all of its subcomponents.
`protected void`	`processComponentEvent(ComponentEvent e)` Processes component events occurring on this component by dispatching them to any registered `ComponentListener` objects.
`protected void`	`processEvent(AWTEvent e)` Processes events occurring on this component.
`protected void`	`processFocusEvent(FocusEvent e)` Processes focus events occurring on this component by dispatching them to any registered `FocusListener` objects.
`protected void`	`processHierarchyBoundsEvent(HierarchyEvent e)` Processes hierarchy bounds events occurring on this component by dispatching them to any registered `HierarchyBoundsListener` objects.
`protected void`	`processHierarchyEvent(HierarchyEvent e)` Processes hierarchy events occurring on this component by dispatching them to any registered `HierarchyListener` objects.
`protected void`	`processInputMethodEvent(InputMethodEvent e)` Processes input method events occurring on this component by dispatching them to any registered `InputMethodListener` objects.
`protected void`	`processKeyEvent(KeyEvent e)` Processes key events occurring on this component by dispatching them to any registered `KeyListener` objects.
`protected void`	`processMouseEvent(MouseEvent e)` Processes mouse events occurring on this component by dispatching them to any registered `MouseListener` objects.
`protected void`	`processMouseMotionEvent(MouseEvent e)` Processes mouse motion events occurring on this component by dispatching them to any registered `MouseMotionListener` objects.
`protected void`	`processMouseWheelEvent(MouseWheelEvent e)` Processes mouse wheel events occurring on this component by dispatching them to any registered `MouseWheelListener` objects.
`void`	`remove(MenuComponent popup)` Removes the specified popup menu from the component.
`void`	`removeComponentListener(ComponentListener l)` Removes the specified component listener so that it no longer receives component events from this component.
`void`	`removeFocusListener(FocusListener l)` Removes the specified focus listener so that it no longer receives focus events from this component.
`void`	`removeHierarchyBoundsListener(HierarchyBoundsListener l)` Removes the specified hierarchy bounds listener so that it no longer receives hierarchy bounds events from this component.
`void`	`removeHierarchyListener(HierarchyListener l)` Removes the specified hierarchy listener so that it no longer receives hierarchy changed events from this component.
`void`	`removeInputMethodListener(InputMethodListener l)` Removes the specified input method listener so that it no longer receives input method events from this component.
`void`	`removeKeyListener(KeyListener l)` Removes the specified key listener so that it no longer receives key events from this component.
`void`	`removeMouseListener(MouseListener l)` Removes the specified mouse listener so that it no longer receives mouse events from this component.
`void`	`removeMouseMotionListener(MouseMotionListener l)` Removes the specified mouse motion listener so that it no longer receives mouse motion events from this component.
`void`	`removeMouseWheelListener(MouseWheelListener l)` Removes the specified mouse wheel listener so that it no longer receives mouse wheel events from this component.
`void`	`removeNotify()` Makes this `Component` undisplayable by destroying it native screen resource.
`void`	`removePropertyChangeListener(PropertyChangeListener listener)` Removes a PropertyChangeListener from the listener list.
`void`	`removePropertyChangeListener(String propertyName, PropertyChangeListener listener)` Removes a PropertyChangeListener from the listener list for a specific property.
`void`	`repaint()` Repaints this component.
`void`	`repaint(int x, int y, int width, int height)` Repaints the specified rectangle of this component.
`void`	`repaint(long tm)` Repaints the component.
`void`	`repaint(long tm, int x, int y, int width, int height)` Repaints the specified rectangle of this component within `tm` milliseconds.
`void`	`requestFocus()` Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window.
`protected boolean`	`requestFocus(boolean temporary)` Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window.
`boolean`	`requestFocusInWindow()` Requests that this Component get the input focus, if this Component's top-level ancestor is already the focused Window.
`protected boolean`	`requestFocusInWindow(boolean temporary)` Requests that this Component get the input focus, if this Component's top-level ancestor is already the focused Window.
`void`	`reshape(int x, int y, int width, int height)` Deprecated. As of JDK version 1.1, replaced by `setBounds(int, int, int, int)`.
`void`	`resize(Dimension d)` Deprecated. As of JDK version 1.1, replaced by `setSize(Dimension)`.
`void`	`resize(int width, int height)` Deprecated. As of JDK version 1.1, replaced by `setSize(int, int)`.
`void`	`setBackground(Color c)` Sets the background color of this component.
`void`	`setBounds(int x, int y, int width, int height)` Moves and resizes this component.
`void`	`setBounds(Rectangle r)` Moves and resizes this component to conform to the new bounding rectangle `r`.
`void`	`setComponentOrientation(ComponentOrientation o)` Sets the language-sensitive orientation that is to be used to order the elements or text within this component.
`void`	`setCursor(Cursor cursor)` Sets the cursor image to the specified cursor.
`void`	`setDropTarget(DropTarget dt)` Associate a `DropTarget` with this component.
`void`	`setEnabled(boolean b)` Enables or disables this component, depending on the value of the parameter `b`.
`void`	`setFocusable(boolean focusable)` Sets the focusable state of this Component to the specified value.
`void`	`setFocusTraversalKeys(int id, Set keystrokes)` Sets the focus traversal keys for a given traversal operation for this Component.
`void`	`setFocusTraversalKeysEnabled(boolean focusTraversalKeysEnabled)` Sets whether focus traversal keys are enabled for this Component.
`void`	`setFont(Font f)` Sets the font of this component.
`void`	`setForeground(Color c)` Sets the foreground color of this component.
`void`	`setIgnoreRepaint(boolean ignoreRepaint)` Sets whether or not paint messages received from the operating system should be ignored.
`void`	`setLocale(Locale l)` Sets the locale of this component.
`void`	`setLocation(int x, int y)` Moves this component to a new location.
`void`	`setLocation(Point p)` Moves this component to a new location.
`void`	`setName(String name)` Sets the name of the component to the specified string.
`void`	`setSize(Dimension d)` Resizes this component so that it has width `d.width` and height `d.height`.
`void`	`setSize(int width, int height)` Resizes this component so that it has width `width` and height `height`.
`void`	`setVisible(boolean b)` Shows or hides this component depending on the value of parameter `b`.
`void`	`show()` Deprecated. As of JDK version 1.1, replaced by `setVisible(boolean)`.
`void`	`show(boolean b)` Deprecated. As of JDK version 1.1, replaced by `setVisible(boolean)`.
`Dimension`	`size()` Deprecated. As of JDK version 1.1, replaced by `getSize()`.
`String`	`toString()` Returns a string representation of this component and its values.
`void`	`transferFocus()` Transfers the focus to the next component, as though this Component were the focus owner.
`void`	`transferFocusBackward()` Transfers the focus to the previous component, as though this Component were the focus owner.
`void`	`transferFocusUpCycle()` Transfers the focus up one focus traversal cycle.
`void`	`update(Graphics g)` Updates this component.
`void`	`validate()` Ensures that this component has a valid layout.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

TOP_ALIGNMENT

public static final float TOP_ALIGNMENT

Ease-of-use constant for getAlignmentY(). Specifies an alignment to the top of the component.

See Also:: getAlignmentY(), Constant Field Values

CENTER_ALIGNMENT

public static final float CENTER_ALIGNMENT

Ease-of-use constant for getAlignmentY and getAlignmentX. Specifies an alignment to the center of the component

See Also:: getAlignmentX(), getAlignmentY(), Constant Field Values

BOTTOM_ALIGNMENT

public static final float BOTTOM_ALIGNMENT

Ease-of-use constant for getAlignmentY. Specifies an alignment to the bottom of the component.

See Also:: getAlignmentY(), Constant Field Values

LEFT_ALIGNMENT

public static final float LEFT_ALIGNMENT

Ease-of-use constant for getAlignmentX. Specifies an alignment to the left side of the component.

See Also:: getAlignmentX(), Constant Field Values

RIGHT_ALIGNMENT

public static final float RIGHT_ALIGNMENT

Ease-of-use constant for getAlignmentX. Specifies an alignment to the right side of the component.

See Also:: getAlignmentX(), Constant Field Values

Constructor Detail

Component

protected Component()

Constructs a new component. Class Component can be extended directly to create a lightweight component that does not utilize an opaque native window. A lightweight component must be hosted by a native container somewhere higher up in the component tree (for example, by a Frame object).

Method Detail

getName

public String getName()

Gets the name of the component.

Returns:: this component's name
Since:: JDK1.1
See Also:: setName(java.lang.String)

setName

public void setName(String name)

Sets the name of the component to the specified string.

Parameters:: name - the string that is to be this component's name
Since:: JDK1.1
See Also:: getName()

getParent

public Container getParent()

Gets the parent of this component.

Returns:: the parent container of this component
Since:: JDK1.0

getPeer

public java.awt.peer.ComponentPeer getPeer()

Deprecated. As of JDK version 1.1, programs should not directly manipulate peers; replaced by boolean isDisplayable().

setDropTarget

public void setDropTarget(DropTarget dt)

Associate a DropTarget with this component. The Component will receive drops only if it is enabled.

Parameters:: dt - The DropTarget
See Also:: isEnabled()

getDropTarget

public DropTarget getDropTarget()

Gets the DropTarget associated with this Component.

getGraphicsConfiguration

public GraphicsConfiguration getGraphicsConfiguration()

Gets the GraphicsConfiguration associated with this Component. If the Component has not been assigned a specific GraphicsConfiguration, the GraphicsConfiguration of the Component object's top-level container is returned. If the Component has been created, but not yet added to a Container, this method returns null.

Returns:: the GraphicsConfiguration used by this Component or null
Since:: 1.3

getTreeLock

public final Object getTreeLock()

Gets this component's locking object (the object that owns the thread sychronization monitor) for AWT component-tree and layout operations.

Returns:: this component's locking object

getToolkit

public Toolkit getToolkit()

Gets the toolkit of this component. Note that the frame that contains a component controls which toolkit is used by that component. Therefore if the component is moved from one frame to another, the toolkit it uses may change.

Returns:: the toolkit of this component
Since:: JDK1.0

isValid

public boolean isValid()

Determines whether this component is valid. A component is valid when it is correctly sized and positioned within its parent container and all its children are also valid. Components are invalidated when they are first shown on the screen.

Returns:: true if the component is valid, false otherwise
Since:: JDK1.0
See Also:: validate(), invalidate()

isDisplayable

public boolean isDisplayable()

Determines whether this component is displayable. A component is displayable when it is connected to a native screen resource.

A component is made displayable either when it is added to a displayable containment hierarchy or when its containment hierarchy is made displayable. A containment hierarchy is made displayable when its ancestor window is either packed or made visible.

A component is made undisplayable either when it is removed from a displayable containment hierarchy or when its containment hierarchy is made undisplayable. A containment hierarchy is made undisplayable when its ancestor window is disposed.

Returns:: true if the component is displayable, false otherwise
Since:: 1.2
See Also:: Container.add(Component), Window.pack(), Window.show(), Container.remove(Component), Window.dispose()

isVisible

public boolean isVisible()

Determines whether this component should be visible when its parent is visible. Components are initially visible, with the exception of top level components such as Frame objects.

Returns:: true if the component is visible, false otherwise
Since:: JDK1.0
See Also:: setVisible(boolean)

isShowing

public boolean isShowing()

Determines whether this component is showing on screen. This means that the component must be visible, and it must be in a container that is visible and showing.

Returns:: true if the component is showing, false otherwise
Since:: JDK1.0
See Also:: setVisible(boolean)

isEnabled

public boolean isEnabled()

Determines whether this component is enabled. An enabled component can respond to user input and generate events. Components are enabled initially by default. A component may be enabled or disabled by calling its setEnabled method.

Returns:: true if the component is enabled, false otherwise
Since:: JDK1.0
See Also:: setEnabled(boolean)

setEnabled

public void setEnabled(boolean b)

Enables or disables this component, depending on the value of the parameter b. An enabled component can respond to user input and generate events. Components are enabled initially by default.

Note: Disabling a lightweight component does not prevent it from receiving MouseEvents.

Parameters:: b - If true, this component is enabled; otherwise this component is disabled
Since:: JDK1.1
See Also:

java.awt Class Component