Gets the name of the component.
Sets the name of the component to the specified string.
name - the string that is to be this component's name
Gets the parent of this component.
Associate a DropTarget with this component. The Component will receive drops only if it is enabled.
dt - The DropTarget
Gets the DropTarget associated with this Component.
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.
GraphicsConfiguration used by this Component or null
()
Gets this component's locking object (the object that owns the thread synchronization monitor) for AWT component-tree and layout operations.
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.
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. In order to account for peers' size requirements, components are invalidated before they are first shown on the screen. By the time the parent container is fully realized, all its components will be valid.
true if the component is valid, false otherwise
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.
true if the component is displayable, false otherwise
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.
true if the component is visible, false otherwise
Returns the position of the mouse pointer in this
Component
's coordinate space if the
Component
is directly under the mouse pointer, otherwise returns
null
. If the
Component
is not showing on the screen, this method returns
null
even if the mouse pointer is above the area where the
Component
would be displayed. If the
Component
is partially or fully obscured by other
Component
s or native windows, this method returns a non-null value only if the mouse pointer is located above the unobscured part of the
Component
.
For Containers it returns a non-null value if the mouse is above the Container itself or above any of its descendants. Use Container.getMousePosition(boolean) if you need to exclude children.
Sometimes the exact mouse coordinates are not important, and the only thing that matters is whether a specific Component is under the mouse pointer. If the return value of this method is null, mouse pointer is not directly above the Component.
Component, or null
HeadlessException - if GraphicsEnvironment.isHeadless() returns true
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.
Note: sometimes there is no way to detect whether the Component is actually visible to the user. This can happen when:
ScrollPane but the Component is not currently in the scroll pane's view port.Component is obscured by another Component or Container.true if the component is showing, false otherwise
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.
true if the component is enabled, false otherwise
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.
Note: Disabling a heavyweight container prevents all components in this container from receiving any input events. But disabling a lightweight container affects only this container.
b - If true, this component is enabled; otherwise this component is disabled
Enables or disables this component.
b - true to enable this component; otherwise false
public boolean isDoubleBuffered()
Returns true if this component is painted to an offscreen image ("buffer") that's copied to the screen later. Component subclasses that support double buffering should override this method to return true if double buffering is enabled.
public void enableInputMethods(boolean enable)
Enables or disables input method support for this component. If input method support is enabled and the component also processes key events, incoming events are offered to the current input method and will only be processed by the component or dispatched to its listeners if the input method does not consume them. By default, input method support is enabled.
enable - true to enable, false to disable
public void setVisible(boolean b)
Shows or hides this component depending on the value of parameter
b
.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
b - if true, shows this component; otherwise, hides this component
Makes this component visible or invisible.
b - true to make this component visible; otherwise false
()
Gets the foreground color of this component.
Sets the foreground color of this component.
c - the color to become this component's foreground color; if this parameter is null then this component will inherit the foreground color of its parent
public boolean isForegroundSet()
Returns whether the foreground color has been explicitly set for this Component. If this method returns false, this Component is inheriting its foreground color from an ancestor.
true if the foreground color has been explicitly set for this Component; false otherwise.
()
Gets the background color of this component.
The background color affects each component differently and the parts of the component that are affected by the background color may differ between operating systems.
c - the color to become this component's color; if this parameter is null, then this component will inherit the background color of its parent
public boolean isBackgroundSet()
Returns whether the background color has been explicitly set for this Component. If this method returns false, this Component is inheriting its background color from an ancestor.
true if the background color has been explicitly set for this Component; false otherwise.
Gets the font of this component.
getFont in interface MenuContainer
This method changes layout-related information, and therefore, invalidates the component hierarchy.
f - the font to become this component's font; if this parameter is null then this component will inherit the font of its parent
public boolean isFontSet()
Returns whether the font has been explicitly set for this Component. If this method returns false, this Component is inheriting its font from an ancestor.
true if the font has been explicitly set for this Component; false otherwise.
Gets the locale of this component.
IllegalComponentStateException - if the Component does not have its own locale and has not yet been added to a containment hierarchy such that the locale can be determined from the containing parent
This method changes layout-related information, and therefore, invalidates the component hierarchy.
l - the locale to become this component's locale
Gets the instance of ColorModel used to display the component on the output device.
ColorModelComponentPeer.getColorModel()Toolkit.getColorModel()()
Due to the asynchronous nature of native event handling, this method can return outdated values (for instance, after several calls of setLocation() in rapid succession). For this reason, the recommended method of obtaining a component's position is within java.awt.event.ComponentListener.componentMoved(), which is called after the operating system has finished moving the component.
Point representing the top-left corner of the component's bounds in the coordinate space of the component's parent
()
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.
Point representing the top-left corner of the component's bounds in the coordinate space of the screen
IllegalComponentStateException - if the component is not showing on the screen
Returns the location of this component's top left corner.
public void setLocation(int x, int y)
Moves this component to a new location. The top-left corner of the new location is specified by the
x
and
y
parameters in the coordinate space of this component's parent.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
x - the x-coordinate of the new location's top-left corner in the parent's coordinate space
y - the y-coordinate of the new location's top-left corner in the parent's coordinate space
Moves this component to a new location.
x - the x-coordinate of the new location's top-left corner in the parent's coordinate space
y - the y-coordinate of the new location's top-left corner in the parent's coordinate space
Moves this component to a new location. The top-left corner of the new location is specified by point
p
. Point
p
is given in the parent's coordinate space.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
p - the point defining the top-left corner of the new location, given in the coordinate space of this component's parent
Returns the size of this component in the form of a Dimension object. The height field of the Dimension object contains this component's height, and the width field of the Dimension object contains this component's width.
Dimension object that indicates the size of this component
Returns the size of this component in the form of a Dimension object.
Dimension object that indicates the size of this component
public void setSize(int width, int height)
Resizes this component so that it has width
width
and height
height
.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
width - the new width of this component in pixels
height - the new height of this component in pixels
Resizes this component.
width - the new width of the component
height - the new height of the component
Resizes this component so that it has width
d.width
and height
d.height
.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
d - the dimension specifying the new size of this component
NullPointerException - if d is null
Resizes this component so that it has width d.width and height d.height.
d - the new size of this component
Gets the bounds of this component in the form of a Rectangle object. The bounds specify this component's width, height, and location relative to its parent.
Returns the bounding rectangle of this component.
public void setBounds(int x, int y, int width, int height)
Moves and resizes this component. The new location of the top-left corner is specified by
x
and
y
, and the new size is specified by
width
and
height
.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
x - the new x-coordinate of this component
y - the new y-coordinate of this component
width - the new width of this component
height - the new height of this component
Reshapes the bounding rectangle for this component.
x - the x coordinate of the upper left corner of the rectangle
y - the y coordinate of the upper left corner of the rectangle
width - the width of the rectangle
height - the height of the rectangle
Moves and resizes this component to conform to the new bounding rectangle
r
. This component's new position is specified by
r.x
and
r.y
, and its new size is specified by
r.width
and
r.height
This method changes layout-related information, and therefore, invalidates the component hierarchy.
r - the new bounding rectangle for this component
NullPointerException - if r is null
public int getX()
Returns the current x coordinate of the components origin. This method is preferable to writing component.getBounds().x, or component.getLocation().x because it doesn't cause any heap allocations.
public int getY()
Returns the current y coordinate of the components origin. This method is preferable to writing component.getBounds().y, or component.getLocation().y because it doesn't cause any heap allocations.
public int getWidth()
Returns the current width of this component. This method is preferable to writing component.getBounds().width, or component.getSize().width because it doesn't cause any heap allocations.
public int getHeight()
Returns the current height of this component. This method is preferable to writing component.getBounds().height, or component.getSize().height because it doesn't cause any heap allocations.
Stores the bounds of this component into "return value" rv and return rv. If rv is null a new Rectangle is allocated. This version of getBounds is useful if the caller wants to avoid allocating a new Rectangle object on the heap.
rv - the return value, modified to the components bounds
Stores the width/height of this component into "return value" rv and return rv. If rv is null a new Dimension object is allocated. This version of getSize is useful if the caller wants to avoid allocating a new Dimension object on the heap.
rv - the return value, modified to the components size
Stores the x,y origin of this component into "return value" rv and return rv. If rv is null a new Point is allocated. This version of getLocation is useful if the caller wants to avoid allocating a new Point object on the heap.
rv - the return value, modified to the components location
public boolean isOpaque()
Returns true if this component is completely opaque, returns false by default.
An opaque component paints every pixel within its rectangular region. A non-opaque component paints only some of its pixels, allowing the pixels underneath it to "show through". A component that does not fully paint its pixels therefore provides a degree of transparency.
Subclasses that guarantee to always completely paint their contents should override this method and return true.
public boolean isLightweight()
A lightweight component doesn't have a native toolkit peer. Subclasses of
Component
and
Container
, other than the ones defined in this package like
Button
or
Scrollbar
, are lightweight. All of the Swing components are lightweights.
This method will always return false if this component is not displayable because it is impossible to determine the weight of an undisplayable component.
Sets the preferred size of this component to a constant value. Subsequent calls to getPreferredSize will always return this value. Setting the preferred size to null restores the default behavior.
preferredSize - The new preferred size, or null
public boolean isPreferredSizeSet()
Returns true if the preferred size has been set to a non-null value otherwise returns false.
setPreferredSize has been invoked with a non-null value.
Gets the preferred size of this component.
Returns the component's preferred size.
Sets the minimum size of this component to a constant value. Subsequent calls to getMinimumSize will always return this value. Setting the minimum size to null restores the default behavior.
minimumSize - the new minimum size of this component
public boolean isMinimumSizeSet()
Returns whether or not setMinimumSize has been invoked with a non-null value.
setMinimumSize has been invoked with a non-null value.
Gets the minimum size of this component.
Returns the minimum size of this component.
Sets the maximum size of this component to a constant value. Subsequent calls to getMaximumSize will always return this value. Setting the maximum size to null restores the default behavior.
maximumSize - a Dimension containing the desired maximum allowable size
public boolean isMaximumSizeSet()
Returns true if the maximum size has been set to a non-null value otherwise returns false.
maximumSize is non-null, false otherwise
Gets the maximum size of this component.
public float getAlignmentX()
Returns the alignment along the x axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.
public float getAlignmentY()
Returns the alignment along the y axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.
public int getBaseline(int width, int height)
Returns the baseline. The baseline is measured from the top of the component. This method is primarily meant for
LayoutManager
s to align components along their baseline. A return value less than 0 indicates this component does not have a reasonable baseline and that
LayoutManager
s should not align this component on its baseline.
The default implementation returns -1. Subclasses that support baseline should override appropriately. If a value >= 0 is returned, then the component has a valid baseline for any size >= the minimum size and getBaselineResizeBehavior can be used to determine how the baseline changes with size.
width - the width to get the baseline for
height - the height to get the baseline for
IllegalArgumentException - if width or height is < 0
The default implementation returns BaselineResizeBehavior.OTHER. Subclasses that have a baseline should override appropriately. Subclasses should never return null; if the baseline can not be calculated return BaselineResizeBehavior.OTHER. Callers should first ask for the baseline using getBaseline and if a value >= 0 is returned use this method. It is acceptable for this method to return a value other than BaselineResizeBehavior.OTHER even if getBaseline returns a value less than 0.
public void doLayout()
Prompts the layout manager to lay out this component. This is usually called when the component (more specifically, container) is validated.
public void validate()
The meaning of the term validating is defined by the ancestors of this class. See Container.validate() for more details.
public void invalidate()
Invalidates this component and its ancestors.
By default, all the ancestors of the component up to the top-most container of the hierarchy are marked invalid. If the java.awt.smartInvalidate system property is set to true, invalidation stops on the nearest validate root of this component. Marking a container invalid indicates that the container needs to be laid out.
This method is called automatically when any layout-related information changes (e.g. setting the bounds of the component, or adding the component to a container).
This method might be called often, so it should work fast.
public void revalidate()
Revalidates the component hierarchy up to the nearest validate root.
This method first invalidates the component hierarchy starting from this component up to the nearest validate root. Afterwards, the component hierarchy is validated starting from the nearest validate root.
This is a convenience method supposed to help application developers avoid looking for validate roots manually. Basically, it's equivalent to first calling the invalidate() method on this component, and then calling the validate() method on the nearest validate root.
Creates a graphics context for this component. This method will return null if this component is currently not displayable.
null if it has none
Gets the font metrics for the specified font. Warning: Since Font metrics are affected by the
FontRenderContext
and this method does not provide one, it can return only metrics for the default render context which may not match that used when rendering on the Component if
Graphics2D
functionality is being used. Instead metrics can be obtained at rendering time by calling
Graphics.getFontMetrics()
or text measurement APIs on the
Font
class.
font - the font for which font metrics is to be obtained
font
getFont()ComponentPeer.getFontMetrics(Font)Toolkit.getFontMetrics(Font)Sets the cursor image to the specified cursor. This cursor image is displayed when the
contains
method for this component returns true for the current cursor location, and this Component is visible, displayable, and enabled. Setting the cursor of a
Container
causes that cursor to be displayed within all of the container's subcomponents, except for those that have a non-
null
cursor.
The method may have no visual effect if the Java platform implementation and/or the native system do not support changing the mouse cursor shape.
cursor - One of the constants defined by the Cursor class; if this parameter is null then this component will inherit the cursor of its parent
Gets the cursor set in the component. If the component does not have a cursor set, the cursor of its parent is returned. If no cursor is set in the entire hierarchy, Cursor.DEFAULT_CURSOR is returned.
public boolean isCursorSet()
Returns whether the cursor has been explicitly set for this Component. If this method returns false, this Component is inheriting its cursor from an ancestor.
true if the cursor has been explicitly set for this Component; false otherwise.
Paints this component.
This method is called when the contents of the component should be painted; such as when the component is first being shown or is damaged and in need of repair. The clip rectangle in the Graphics parameter is set to the area which needs to be painted. Subclasses of Component that override this method need not call super.paint(g).
For performance reasons, Components with zero width or height aren't considered to need painting when they are first shown, and also aren't considered to need repair.
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.
g - the graphics context to use for painting
Updates this component.
If this component is not a lightweight component, the AWT calls the update method in response to a call to repaint. You can assume that the background is not cleared.
The update method of Component calls this component's paint method to redraw this component. This method is commonly overridden by subclasses which need to do additional work in response to a call to repaint. Subclasses of Component that override this method should either call super.update(g), or call paint(g) directly from their update method.
The origin of the graphics context, its (0, 0) coordinate point, is the top-left corner of this component. The clipping region of the graphics context is the bounding rectangle of this component.
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.
g - the specified context to use for updating
The origin of the graphics context, its (0, 0) coordinate point, is the top-left corner of this component. The clipping region of the graphics context is the bounding rectangle of this component.
g - the graphics context to use for painting
public void repaint()
Repaints this component.
If this component is a lightweight component, this method causes a call to this component's paint method as soon as possible. Otherwise, this method causes a call to this component's update method as soon as possible.
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.
public void repaint(long tm)
Repaints the component. If this component is a lightweight component, this results in a call to
paint
within
tm
milliseconds.
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.
tm - maximum time in milliseconds before update
public void repaint(int x, int y, int width, int height)
Repaints the specified rectangle of this component.
If this component is a lightweight component, this method causes a call to this component's paint method as soon as possible. Otherwise, this method causes a call to this component's update method as soon as possible.
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.
x - the x coordinate
y - the y coordinate
width - the width
height - the height
public void repaint(long tm, int x, int y, int width, int height)
Repaints the specified rectangle of this component within
tm
milliseconds.
If this component is a lightweight component, this method causes a call to this component's paint method. Otherwise, this method causes a call to this component's update method.
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.
tm - maximum time in milliseconds before update
x - the x coordinate
y - the y coordinate
width - the width
height - the height
Prints this component. Applications should override this method for components that must do special processing before being printed or should be printed differently than they are painted.
The default implementation of this method calls the paint method.
The origin of the graphics context, its (0, 0) coordinate point, is the top-left corner of this component. The clipping region of the graphics context is the bounding rectangle of this component.
g - the graphics context to use for printing
The origin of the graphics context, its (0, 0) coordinate point, is the top-left corner of this component. The clipping region of the graphics context is the bounding rectangle of this component.
g - the graphics context to use for printing
Repaints the component when the image has changed. This
imageUpdate
method of an
ImageObserver
is called when more information about an image which had been previously requested using an asynchronous routine such as the
drawImage
method of
Graphics
becomes available. See the definition of
imageUpdate
for more information on this method and its arguments.
The imageUpdate method of Component incrementally draws an image on the component as more of the bits of the image are available.
If the system property awt.image.incrementaldraw is missing or has the value true, the image is incrementally drawn. If the system property has any other value, then the image is not drawn until it has been completely loaded.
Also, if incremental drawing is in effect, the value of the system property awt.image.redrawrate is interpreted as an integer to give the maximum redraw rate, in milliseconds. If the system property is missing or cannot be interpreted as an integer, the redraw rate is once every 100ms.
The interpretation of the x, y, width, and height arguments depends on the value of the infoflags argument.
imageUpdate in interface ImageObserver
img - the image being observed
infoflags - see imageUpdate for more information
x - the x coordinate
y - the y coordinate
w - the width
h - the height
false if the infoflags indicate that the image is completely loaded; true otherwise.
ImageObserverGraphics.drawImage(Image, int, int, Color, java.awt.image.ImageObserver)Graphics.drawImage(Image, int, int, java.awt.image.ImageObserver)Graphics.drawImage(Image, int, int, int, int, Color, java.awt.image.ImageObserver)Graphics.drawImage(Image, int, int, int, int, java.awt.image.ImageObserver)ImageObserver.imageUpdate(java.awt.Image, int, int, int, int, int)Creates an image from the specified image producer.
producer - the image producer
Creates an off-screen drawable image to be used for double buffering.
width - the specified width
height - the specified height
null value if the component is not displayable or GraphicsEnvironment.isHeadless() returns true.
Creates a volatile off-screen drawable image to be used for double buffering.
width - the specified width
height - the specified height
null value if the component is not displayable or GraphicsEnvironment.isHeadless() returns true.
Creates a volatile off-screen drawable image, with the given capabilities. The contents of this image may be lost at any time due to operating system issues, so the image must be managed via the VolatileImage interface.
width - the specified width
height - the specified height
caps - the image capabilities
null value if the component is not displayable or GraphicsEnvironment.isHeadless() returns true.
AWTException - if an image with the specified capabilities cannot be created
Prepares an image for rendering on this component. The image data is downloaded asynchronously in another thread and the appropriate screen representation of the image is generated.
image - the Image for which to prepare a screen representation
observer - the ImageObserver object to be notified as the image is being prepared
true if the image has already been fully prepared; false otherwise
The image data is downloaded asynchronously in another thread, and an appropriately scaled screen representation of the image is generated.
image - the instance of Image for which to prepare a screen representation
width - the width of the desired screen representation
height - the height of the desired screen representation
observer - the ImageObserver object to be notified as the image is being prepared
true if the image has already been fully prepared; false otherwise
Returns the status of the construction of a screen representation of the specified image.
This method does not cause the image to begin loading. An application must use the prepareImage method to force the loading of an image.
Information on the flags returned by this method can be found with the discussion of the ImageObserver interface.
image - the Image object whose status is being checked
observer - the ImageObserver object to be notified as the image is being prepared
ImageObserver flags indicating what information about the image is currently available
Returns the status of the construction of a screen representation of the specified image.
This method does not cause the image to begin loading. An application must use the prepareImage method to force the loading of an image.
The checkImage method of Component calls its peer's checkImage method to calculate the flags. If this component does not yet have a peer, the component's toolkit's checkImage method is called instead.
Information on the flags returned by this method can be found with the discussion of the ImageObserver interface.
image - the Image object whose status is being checked
width - the width of the scaled version whose status is to be checked
height - the height of the scaled version whose status is to be checked
observer - the ImageObserver object to be notified as the image is being prepared
ImageObserver flags indicating what information about the image is currently available
public void setIgnoreRepaint(boolean ignoreRepaint)
This is useful, for example, if running under full-screen mode and better performance is desired, or if page-flipping is used as the buffer strategy.
ignoreRepaint - true if the paint messages from the OS should be ignored; otherwise false
public boolean getIgnoreRepaint()
Returns whether or not paint messages received from the operating system should be ignored.
public 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.
x - the x coordinate of the point
y - the y coordinate of the point
true if the point is within the component; otherwise false
Checks whether the point is inside of this component.
x - the x coordinate of the point
y - the y coordinate of the point
true if the point is within the component; otherwise false
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.
p - the point
true if the point is within the component; otherwise false
NullPointerException - if p is null
Determines if this component or one of its immediate subcomponents contains the (
x,
y) location, and if so, returns the containing component. This method only looks one level deep. If the point (
x,
y) is inside a subcomponent that itself has subcomponents, it does not go looking down the subcomponent tree.
The locate method of Component simply returns the component itself if the (x, y) coordinate location is inside its bounding box, and null otherwise.
x - the x coordinate
y - the y coordinate
null if the location is outside this component
Returns the component occupying the position specified (this component, or immediate child component, or null if neither of the first two occupies the location).
x - the x coordinate to search for components at
y - the y coordinate to search for components at
null
Returns the component or subcomponent that contains the specified point.
p - the point
null
e - the event to deliver
Dispatches an event to this component or one of its sub components. Calls processEvent before returning for 1.1-style events which have been enabled for the Component.
e - the event
Posts an event to the listeners.
postEvent in interface MenuContainer
e - the event to dispatch
Adds the specified component listener to receive component events from this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the component listener
Removes the specified component listener so that it no longer receives component events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the component listener
Returns an array of all the component listeners registered on this component.
ComponentListeners of this component or an empty array if no component listeners are currently registered
Adds the specified focus listener to receive focus events from this component when this component gains input focus. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the focus listener
Removes the specified focus listener so that it no longer receives focus events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the focus listener
Returns an array of all the focus listeners registered on this component.
FocusListeners or an empty array if no component listeners are currently registered
Adds the specified hierarchy listener to receive hierarchy changed events from this component when the hierarchy to which this container belongs changes. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the hierarchy listener
Removes the specified hierarchy listener so that it no longer receives hierarchy changed events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the hierarchy listener
Returns an array of all the hierarchy listeners registered on this component.
HierarchyListeners or an empty array if no hierarchy listeners are currently registered
Adds the specified hierarchy bounds listener to receive hierarchy bounds events from this component when the hierarchy to which this container belongs changes. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the hierarchy bounds listener
Removes the specified hierarchy bounds listener so that it no longer receives hierarchy bounds events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the hierarchy bounds listener
Returns an array of all the hierarchy bounds listeners registered on this component.
HierarchyBoundsListeners or an empty array if no hierarchy bounds listeners are currently registered
Refer to AWT Threading Issues for details on AWT's threading model.
l - the key listener.
Removes the specified key listener so that it no longer receives key events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the key listener
Returns an array of all the key listeners registered on this component.
KeyListeners or an empty array if no key listeners are currently registered
Adds the specified mouse listener to receive mouse events from this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the mouse listener
Removes the specified mouse listener so that it no longer receives mouse events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the mouse listener
Returns an array of all the mouse listeners registered on this component.
MouseListeners or an empty array if no mouse listeners are currently registered
Adds the specified mouse motion listener to receive mouse motion events from this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the mouse motion listener
Removes the specified mouse motion listener so that it no longer receives mouse motion events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the mouse motion listener
Returns an array of all the mouse motion listeners registered on this component.
MouseMotionListeners or an empty array if no mouse motion listeners are currently registered
Adds the specified mouse wheel listener to receive mouse wheel events from this component. Containers also receive mouse wheel events from sub-components.
For information on how mouse wheel events are dispatched, see the class description for MouseWheelEvent.
If l is null, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the mouse wheel listener
Refer to AWT Threading Issues for details on AWT's threading model.
l - the mouse wheel listener.
Returns an array of all the mouse wheel listeners registered on this component.
MouseWheelListeners or an empty array if no mouse wheel listeners are currently registered
Adds the specified input method listener to receive input method events from this component. A component will only receive input method events from input methods if it also overrides
getInputMethodRequests
to return an
InputMethodRequests
instance. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the input method listener
Removes the specified input method listener so that it no longer receives input method events from this component. This method performs no function, nor does it throw an exception, if the listener specified by the argument was not previously added to this component. If listener
l
is
null
, no exception is thrown and no action is performed.
Refer to AWT Threading Issues for details on AWT's threading model.
l - the input method listener
Returns an array of all the input method listeners registered on this component.
InputMethodListeners or an empty array if no input method listeners are currently registered
Returns an array of all the objects currently registered as
FooListener
s upon this
Component
.
FooListener
s are registered using the
addFooListener
method.
You can specify the listenerType argument with a class literal, such as FooListener.class. For example, you can query a Component c for its mouse listeners with the following code:
MouseListener[] mls = (MouseListener[])(c.getListeners(MouseListener.class));
If no such listeners exist, this method returns an empty array.
T - the type of the listeners
listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
FooListeners on this component, or an empty array if no such listeners have been added
ClassCastException - if listenerType doesn't specify a class or interface that implements java.util.EventListener
NullPointerException - if listenerType is null
Gets the input method request handler which supports requests from input methods for this component. A component that supports on-the-spot text input must override this method to return an InputMethodRequests instance. At the same time, it also has to handle input method events.
null by default
Gets the input context used by this component for handling the communication with input methods when text is entered in this component. By default, the input context used for the parent component is returned. Components may override this to return a private input context.
null if no context can be determined
protected final void enableEvents(long eventsToEnable)
Enables the events defined by the specified event mask parameter to be delivered to this component.
Event types are automatically enabled when a listener for that event type is added to the component.
This method only needs to be invoked by subclasses of Component which desire to have the specified event types delivered to processEvent regardless of whether or not a listener is registered.
eventsToEnable - the event mask defining the event types
protected final void disableEvents(long eventsToDisable)
Disables the events defined by the specified event mask parameter from being delivered to this component.
eventsToDisable - the event mask defining the event types
Potentially coalesce an event being posted with an existing event. This method is called by
EventQueue.postEvent
if an event with the same ID as the event to be posted is found in the queue (both events must have this component as their source). This method either returns a coalesced event which replaces the existing event (and the new event is then discarded), or
null
to indicate that no combining should be done (add the second event to the end of the queue). Either event parameter may be modified and returned, as the other one is discarded unless
null
is returned.
This implementation of coalesceEvents coalesces two event types: mouse move (and drag) events, and paint (and update) events. For mouse move events the last event is always returned, causing intermediate moves to be discarded. For paint events, the new event is coalesced into a complex RepaintArea in the peer. The new AWTEvent is always returned.
existingEvent - the event already on the EventQueue
newEvent - the event being posted to the EventQueue
null indicating that no coalescing was done
Processes events occurring on this component. By default this method calls the appropriate
process<event type>Event
method for the given class of event.
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the event
processComponentEvent(java.awt.event.ComponentEvent)processFocusEvent(java.awt.event.FocusEvent)processKeyEvent(java.awt.event.KeyEvent)processMouseEvent(java.awt.event.MouseEvent)processMouseMotionEvent(java.awt.event.MouseEvent)processInputMethodEvent(java.awt.event.InputMethodEvent)processHierarchyEvent(java.awt.event.HierarchyEvent)processMouseWheelEvent(java.awt.event.MouseWheelEvent)Processes component events occurring on this component by dispatching them to any registered
ComponentListener
objects.
This method is not called unless component events are enabled for this component. Component events are enabled when one of the following occurs:
ComponentListener object is registered via addComponentListener.enableEvents.Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the component event
Processes focus events occurring on this component by dispatching them to any registered
FocusListener
objects.
This method is not called unless focus events are enabled for this component. Focus events are enabled when one of the following occurs:
FocusListener object is registered via addFocusListener.enableEvents.If focus events are enabled for a Component, the current KeyboardFocusManager determines whether or not a focus event should be dispatched to registered FocusListener objects. If the events are to be dispatched, the KeyboardFocusManager calls the Component's dispatchEvent method, which results in a call to the Component's processFocusEvent method.
If focus events are enabled for a Component, calling the Component's dispatchEvent method with a FocusEvent as the argument will result in a call to the Component's processFocusEvent method regardless of the current KeyboardFocusManager.
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the focus event
Processes key events occurring on this component by dispatching them to any registered
KeyListener
objects.
This method is not called unless key events are enabled for this component. Key events are enabled when one of the following occurs:
KeyListener object is registered via addKeyListener.enableEvents.If key events are enabled for a Component, the current KeyboardFocusManager determines whether or not a key event should be dispatched to registered KeyListener objects. The DefaultKeyboardFocusManager will not dispatch key events to a Component that is not the focus owner or is not showing.
As of J2SE 1.4, KeyEvents are redirected to the focus owner. Please see the Focus Specification for further information.
Calling a Component's dispatchEvent method with a KeyEvent as the argument will result in a call to the Component's processKeyEvent method regardless of the current KeyboardFocusManager as long as the component is showing, focused, and enabled, and key events are enabled on it.
If the event parameter is null the behavior is unspecified and may result in an exception.
e - the key event
Processes mouse events occurring on this component by dispatching them to any registered
MouseListener
objects.
This method is not called unless mouse events are enabled for this component. Mouse events are enabled when one of the following occurs:
MouseListener object is registered via addMouseListener.enableEvents.Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the mouse event
Processes mouse motion events occurring on this component by dispatching them to any registered
MouseMotionListener
objects.
This method is not called unless mouse motion events are enabled for this component. Mouse motion events are enabled when one of the following occurs:
MouseMotionListener object is registered via addMouseMotionListener.enableEvents.Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the mouse motion event
Processes mouse wheel events occurring on this component by dispatching them to any registered
MouseWheelListener
objects.
This method is not called unless mouse wheel events are enabled for this component. Mouse wheel events are enabled when one of the following occurs:
MouseWheelListener object is registered via addMouseWheelListener.enableEvents.For information on how mouse wheel events are dispatched, see the class description for MouseWheelEvent.
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the mouse wheel event
Processes input method events occurring on this component by dispatching them to any registered
InputMethodListener
objects.
This method is not called unless input method events are enabled for this component. Input method events are enabled when one of the following occurs:
InputMethodListener object is registered via addInputMethodListener.enableEvents.Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the input method event
Processes hierarchy events occurring on this component by dispatching them to any registered
HierarchyListener
objects.
This method is not called unless hierarchy events are enabled for this component. Hierarchy events are enabled when one of the following occurs:
HierarchyListener object is registered via addHierarchyListener.enableEvents.Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the hierarchy event
Processes hierarchy bounds events occurring on this component by dispatching them to any registered
HierarchyBoundsListener
objects.
This method is not called unless hierarchy bounds events are enabled for this component. Hierarchy bounds events are enabled when one of the following occurs:
HierarchyBoundsListener object is registered via addHierarchyBoundsListener.enableEvents.Note that if the event parameter is null the behavior is unspecified and may result in an exception.
e - the hierarchy event
evt - the event to handle
true if the event was handled, false otherwise
evt - the event to handle
x - the x coordinate
y - the y coordinate
false
evt - the event to handle
x - the x coordinate
y - the y coordinate
false
evt - the event to handle
x - the x coordinate
y - the y coordinate
false
evt - the event to handle
x - the x coordinate
y - the y coordinate
false
evt - the event to handle
x - the x coordinate
y - the y coordinate
false
evt - the event to handle
x - the x coordinate
y - the y coordinate
false
evt - the event to handle
key - the key pressed
false
evt - the event to handle
key - the key pressed
false
evt - the event to handle
what - the object acted on
false
public void addNotify()
Makes this
Component
displayable by connecting it to a native screen resource. This method is called internally by the toolkit and should not be called directly by programs.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
public void removeNotify()
Makes this
Component
undisplayable by destroying it native screen resource.
This method is called by the toolkit internally and should not be called directly by programs. Code overriding this method should call super.removeNotify as the first line of the overriding method.
evt - the event to handle
what - the object focused
false
evt - the event to handle
what - the object focused
false
Returns whether this Component can become the focus owner.
true if this Component is focusable; false otherwise
public boolean isFocusable()
Returns whether this Component can be focused.
true if this Component is focusable; false otherwise.
public void setFocusable(boolean focusable)
Sets the focusable state of this Component to the specified value. This value overrides the Component's default focusability.
focusable - indicates whether this Component is focusable
Sets the focus traversal keys for a given traversal operation for this Component.
The default values for a Component's focus traversal keys are implementation-dependent. Sun recommends that all implementations for a particular native platform use the same default values. The recommendations for Windows and Unix are listed below. These recommendations are used in the Sun AWT implementations.
Recommended default values for a Component's focus traversal keys Identifier Meaning Default KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS Normal forward keyboard traversal TAB on KEY_PRESSED, CTRL-TAB on KEY_PRESSED KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS Normal reverse keyboard traversal SHIFT-TAB on KEY_PRESSED, CTRL-SHIFT-TAB on KEY_PRESSED KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS Go up one focus traversal cycle noneTo disable a traversal key, use an empty Set; Collections.EMPTY_SET is recommended.
Using the AWTKeyStroke API, client code can specify on which of two specific KeyEvents, KEY_PRESSED or KEY_RELEASED, the focus traversal operation will occur. Regardless of which KeyEvent is specified, however, all KeyEvents related to the focus traversal key, including the associated KEY_TYPED event, will be consumed, and will not be dispatched to any Component. It is a runtime error to specify a KEY_TYPED event as mapping to a focus traversal operation, or to map the same event to multiple default focus traversal operations.
If a value of null is specified for the Set, this Component inherits the Set from its parent. If all ancestors of this Component have null specified for the Set, then the current KeyboardFocusManager's default Set is used.
This method may throw a ClassCastException if any Object in keystrokes is not an AWTKeyStroke.
id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, or KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS
keystrokes - the Set of AWTKeyStroke for the specified operation
IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, or KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or if keystrokes contains null, or if any keystroke represents a KEY_TYPED event, or if any keystroke already maps to another focus traversal operation for this Component
Returns the Set of focus traversal keys for a given traversal operation for this Component. (See
setFocusTraversalKeys
for a full description of each key.)
If a Set of traversal keys has not been explicitly defined for this Component, then this Component's parent's Set is returned. If no Set has been explicitly defined for any of this Component's ancestors, then the current KeyboardFocusManager's default Set is returned.
id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, or KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS
IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, or KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS
public 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. If this method returns false, this Component is inheriting the Set from an ancestor, or from the current KeyboardFocusManager.
id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, or KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS
true if the Set of focus traversal keys for the given focus traversal operation has been explicitly defined for this Component; false otherwise.
IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, or KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS
public void setFocusTraversalKeysEnabled(boolean focusTraversalKeysEnabled)
Sets whether focus traversal keys are enabled for this Component. Components for which focus traversal keys are disabled receive key events for focus traversal keys. Components for which focus traversal keys are enabled do not see these events; instead, the events are automatically converted to traversal operations.
focusTraversalKeysEnabled - whether focus traversal keys are enabled for this Component
public boolean getFocusTraversalKeysEnabled()
Returns whether focus traversal keys are enabled for this Component. Components for which focus traversal keys are disabled receive key events for focus traversal keys. Components for which focus traversal keys are enabled do not see these events; instead, the events are automatically converted to traversal operations.
public void requestFocus()
Requests that this Component get the input focus, and that this Component's top-level ancestor become the focused Window. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this Component is the focus owner until this Component receives a FOCUS_GAINED event. If this request is denied because this Component's top-level Window cannot become the focused Window, the request will be remembered and will be granted when the Window is later focused by the user.
This method cannot be used to set the focus owner to no Component at all. Use KeyboardFocusManager.clearGlobalFocusOwner() instead.
Because the focus behavior of this method is platform-dependent, developers are strongly encouraged to use requestFocusInWindow when possible.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
Requests by the reason of
cause
that this Component get the input focus, and that this Component's top-level ancestor become the focused Window. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this Component is the focus owner until this Component receives a FOCUS_GAINED event.
The focus request effect may also depend on the provided cause value. If this request is succeed the FocusEvent generated in the result will receive the cause value specified as the argument of method. If this request is denied because this Component's top-level Window cannot become the focused Window, the request will be remembered and will be granted when the Window is later focused by the user.
This method cannot be used to set the focus owner to no Component at all. Use KeyboardFocusManager.clearGlobalFocusOwner() instead.
Because the focus behavior of this method is platform-dependent, developers are strongly encouraged to use requestFocusInWindow(FocusEvent.Cause) when possible.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
cause - the cause why the focus is requested
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
. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this component is the focus owner until this component receives a FOCUS_GAINED event. If this request is denied because this component's top-level window cannot become the focused window, the request will be remembered and will be granted when the window is later focused by the user.
This method returns a boolean value. If false is returned, the request is guaranteed to fail. If true is returned, the request will succeed unless it is vetoed, or an extraordinary event, such as disposal of the component's peer, occurs before the request can be granted by the native windowing system. Again, while a return value of true indicates that the request is likely to succeed, developers must never assume that this component is the focus owner until this component receives a FOCUS_GAINED event.
This method cannot be used to set the focus owner to no component at all. Use KeyboardFocusManager.clearGlobalFocusOwner instead.
Because the focus behavior of this method is platform-dependent, developers are strongly encouraged to use requestFocusInWindow when possible.
Every effort will be made to ensure that FocusEvents generated as a result of this request will have the specified temporary value. However, because specifying an arbitrary temporary state may not be implementable on all native windowing systems, correct behavior for this method can be guaranteed only for lightweight Components. This method is not intended for general use, but exists instead as a hook for lightweight component libraries, such as Swing.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
temporary - true if the focus change is temporary, such as when the window loses the focus; for more information on temporary focus changes see the Focus Specification
false if the focus change request is guaranteed to fail; true if it is likely to succeed
Requests by the reason of
cause
that this
Component
get the input focus, and that this
Component
's top-level ancestor become the focused
Window
. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this component is the focus owner until this component receives a FOCUS_GAINED event. If this request is denied because this component's top-level window cannot become the focused window, the request will be remembered and will be granted when the window is later focused by the user.
This method returns a boolean value. If false is returned, the request is guaranteed to fail. If true is returned, the request will succeed unless it is vetoed, or an extraordinary event, such as disposal of the component's peer, occurs before the request can be granted by the native windowing system. Again, while a return value of true indicates that the request is likely to succeed, developers must never assume that this component is the focus owner until this component receives a FOCUS_GAINED event.
The focus request effect may also depend on the provided cause value. If this request is succeed the {FocusEvent} generated in the result will receive the cause value specified as the argument of the method.
This method cannot be used to set the focus owner to no component at all. Use KeyboardFocusManager.clearGlobalFocusOwner instead.
Because the focus behavior of this method is platform-dependent, developers are strongly encouraged to use requestFocusInWindow when possible.
Every effort will be made to ensure that FocusEvents generated as a result of this request will have the specified temporary value. However, because specifying an arbitrary temporary state may not be implementable on all native windowing systems, correct behavior for this method can be guaranteed only for lightweight Components. This method is not intended for general use, but exists instead as a hook for lightweight component libraries, such as Swing.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
temporary - true if the focus change is temporary, such as when the window loses the focus; for more information on temporary focus changes see the Focus Specification
cause - the cause why the focus is requested
false if the focus change request is guaranteed to fail; true if it is likely to succeed
public boolean requestFocusInWindow()
Requests that this Component get the input focus, if this Component's top-level ancestor is already the focused Window. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this Component is the focus owner until this Component receives a FOCUS_GAINED event.
This method returns a boolean value. If false is returned, the request is guaranteed to fail. If true is returned, the request will succeed unless it is vetoed, or an extraordinary event, such as disposal of the Component's peer, occurs before the request can be granted by the native windowing system. Again, while a return value of true indicates that the request is likely to succeed, developers must never assume that this Component is the focus owner until this Component receives a FOCUS_GAINED event.
This method cannot be used to set the focus owner to no Component at all. Use KeyboardFocusManager.clearGlobalFocusOwner() instead.
The focus behavior of this method can be implemented uniformly across platforms, and thus developers are strongly encouraged to use this method over requestFocus when possible. Code which relies on requestFocus may exhibit different focus behavior on different platforms.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
false if the focus change request is guaranteed to fail; true if it is likely to succeed
Requests by the reason of
cause
that this Component get the input focus, if this Component's top-level ancestor is already the focused Window. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this Component is the focus owner until this Component receives a FOCUS_GAINED event.
This method returns a boolean value. If false is returned, the request is guaranteed to fail. If true is returned, the request will succeed unless it is vetoed, or an extraordinary event, such as disposal of the Component's peer, occurs before the request can be granted by the native windowing system. Again, while a return value of true indicates that the request is likely to succeed, developers must never assume that this Component is the focus owner until this Component receives a FOCUS_GAINED event.
The focus request effect may also depend on the provided cause value. If this request is succeed the FocusEvent generated in the result will receive the cause value specified as the argument of the method.
This method cannot be used to set the focus owner to no Component at all. Use KeyboardFocusManager.clearGlobalFocusOwner() instead.
The focus behavior of this method can be implemented uniformly across platforms, and thus developers are strongly encouraged to use this method over requestFocus(FocusEvent.Cause) when possible. Code which relies on requestFocus(FocusEvent.Cause) may exhibit different focus behavior on different platforms.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
cause - the cause why the focus is requested
false if the focus change request is guaranteed to fail; true if it is likely to succeed
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
. This component must be displayable, focusable, visible and all of its ancestors (with the exception of the top-level Window) must be visible for the request to be granted. Every effort will be made to honor the request; however, in some cases it may be impossible to do so. Developers must never assume that this component is the focus owner until this component receives a FOCUS_GAINED event.
This method returns a boolean value. If false is returned, the request is guaranteed to fail. If true is returned, the request will succeed unless it is vetoed, or an extraordinary event, such as disposal of the component's peer, occurs before the request can be granted by the native windowing system. Again, while a return value of true indicates that the request is likely to succeed, developers must never assume that this component is the focus owner until this component receives a FOCUS_GAINED event.
This method cannot be used to set the focus owner to no component at all. Use KeyboardFocusManager.clearGlobalFocusOwner instead.
The focus behavior of this method can be implemented uniformly across platforms, and thus developers are strongly encouraged to use this method over requestFocus when possible. Code which relies on requestFocus may exhibit different focus behavior on different platforms.
Every effort will be made to ensure that FocusEvents generated as a result of this request will have the specified temporary value. However, because specifying an arbitrary temporary state may not be implementable on all native windowing systems, correct behavior for this method can be guaranteed only for lightweight components. This method is not intended for general use, but exists instead as a hook for lightweight component libraries, such as Swing.
Note: Not all focus transfers result from invoking this method. As such, a component may receive focus without this or any of the other requestFocus methods of Component being invoked.
temporary - true if the focus change is temporary, such as when the window loses the focus; for more information on temporary focus changes see the Focus Specification
false if the focus change request is guaranteed to fail; true if it is likely to succeed
()
Returns the Container which is the focus cycle root of this Component's focus traversal cycle. Each focus traversal cycle has only a single focus cycle root and each Component which is not a Container belongs to only a single focus traversal cycle. Containers which are focus cycle roots belong to two cycles: one rooted at the Container itself, and one rooted at the Container's nearest focus-cycle-root ancestor. For such Containers, this method will return the Container's nearest focus-cycle- root ancestor.
Returns whether the specified Container is the focus cycle root of this Component's focus traversal cycle. Each focus traversal cycle has only a single focus cycle root and each Component which is not a Container belongs to only a single focus traversal cycle.
container - the Container to be tested
true if the specified Container is a focus-cycle- root of this Component; false otherwise
public void transferFocus()
Transfers the focus to the next component, as though this Component were the focus owner.
public void transferFocusBackward()
Transfers the focus to the previous component, as though this Component were the focus owner.
public void transferFocusUpCycle()
Transfers the focus up one focus traversal cycle. Typically, the focus owner is set to this Component's focus cycle root, and the current focus cycle root is set to the new focus owner's focus cycle root. If, however, this Component's focus cycle root is a Window, then the focus owner is set to the focus cycle root's default Component to focus, and the current focus cycle root is unchanged.
public boolean hasFocus()
Returns true if this Component is the focus owner. This method is obsolete, and has been replaced by isFocusOwner().
true if this Component is the focus owner; false otherwise
public boolean isFocusOwner()
Returns true if this Component is the focus owner.
true if this Component is the focus owner; false otherwise
()
Returns a string representing the state of this component. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null.
Returns a string representation of this component and its values.
public void list()
Prints a listing of this component to the standard system output stream System.out.
Prints a listing of this component to the specified output stream.
out - a print stream
NullPointerException - if out is null
Prints out a list, starting at the specified indentation, to the specified print stream.
out - a print stream
indent - number of spaces to indent
NullPointerException - if out is null
Prints a listing to the specified print writer.
out - the print writer to print to
NullPointerException - if out is null
Prints out a list, starting at the specified indentation, to the specified print writer.
out - the print writer to print to
indent - the number of spaces to indent
NullPointerException - if out is null
Adds a PropertyChangeListener to the listener list. The listener is registered for all bound properties of this class, including the following:
Note that if this
Component
is inheriting a bound property, then no event will be fired in response to a change in the inherited property.
If listener is null, no exception is thrown and no action is performed.
listener - the property change listener to be added
If listener is null, no exception is thrown and no action is performed.
listener - the PropertyChangeListener to be removed
Returns an array of all the property change listeners registered on this component.
PropertyChangeListeners or an empty array if no property change listeners are currently registered
Adds a PropertyChangeListener to the listener list for a specific property. The specified property may be user-defined, or one of the following:
Note that if this
Component
is inheriting a bound property, then no event will be fired in response to a change in the inherited property.
If propertyName or listener is null, no exception is thrown and no action is taken.
propertyName - one of the property names listed above
listener - the property change listener to be added
Removes a
PropertyChangeListener
from the listener list for a specific property. This method should be used to remove
PropertyChangeListener
s that were registered for a specific bound property.
If propertyName or listener is null, no exception is thrown and no action is taken.
propertyName - a valid property name
listener - the PropertyChangeListener to be removed
Returns an array of all the listeners which have been associated with the named property.
propertyName - the property name
PropertyChangeListeners associated with the named property; if no such listeners have been added or if propertyName is null, an empty array is returned
Support for reporting bound property changes for Object properties. This method can be called when a bound property has changed and it will send the appropriate PropertyChangeEvent to any registered PropertyChangeListeners.
propertyName - the property whose value has changed
oldValue - the property's previous value
newValue - the property's new value
Support for reporting bound property changes for boolean properties. This method can be called when a bound property has changed and it will send the appropriate PropertyChangeEvent to any registered PropertyChangeListeners.
propertyName - the property whose value has changed
oldValue - the property's previous value
newValue - the property's new value
Support for reporting bound property changes for integer properties. This method can be called when a bound property has changed and it will send the appropriate PropertyChangeEvent to any registered PropertyChangeListeners.
propertyName - the property whose value has changed
oldValue - the property's previous value
newValue - the property's new value
Reports a bound property change.
propertyName - the programmatic name of the property that was changed
oldValue - the old value of the property (as a byte)
newValue - the new value of the property (as a byte)
Reports a bound property change.
propertyName - the programmatic name of the property that was changed
oldValue - the old value of the property (as a char)
newValue - the new value of the property (as a char)
Reports a bound property change.
propertyName - the programmatic name of the property that was changed
oldValue - the old value of the property (as a short)
newValue - the new value of the property (as a short)
Reports a bound property change.
propertyName - the programmatic name of the property that was changed
oldValue - the old value of the property (as a long)
newValue - the new value of the property (as a long)
Reports a bound property change.
propertyName - the programmatic name of the property that was changed
oldValue - the old value of the property (as a float)
newValue - the new value of the property (as a float)
Reports a bound property change.
propertyName - the programmatic name of the property that was changed
oldValue - the old value of the property (as a double)
newValue - the new value of the property (as a double)
Sets the language-sensitive orientation that is to be used to order the elements or text within this component. Language-sensitive
LayoutManager
and
Component
subclasses will use this property to determine how to lay out and draw components.
At construction time, a component's orientation is set to ComponentOrientation.UNKNOWN, indicating that it has not been specified explicitly. The UNKNOWN orientation behaves the same as ComponentOrientation.LEFT_TO_RIGHT.
To set the orientation of a single component, use this method. To set the orientation of an entire component hierarchy, use applyComponentOrientation.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
o - the orientation to be set
Retrieves the language-sensitive orientation that is to be used to order the elements or text within this component. LayoutManager and Component subclasses that wish to respect orientation should call this method to get the component's orientation before performing layout or drawing.
Sets the
ComponentOrientation
property of this component and all components contained within it.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
orientation - the new component orientation of this component and the components contained within it.
NullPointerException - if orientation is null.
Gets the AccessibleContext associated with this Component. The method implemented by this base class returns null. Classes that extend Component should implement this method to return the AccessibleContext associated with the subclass.
AccessibleContext of this Component
Sets a 'mixing-cutout' shape for this lightweight component. This method is used exclusively for the purposes of the Heavyweight/Lightweight Components Mixing feature and will have no effect if applied to a heavyweight component. By default a lightweight component is treated as an opaque rectangle for the purposes of the Heavyweight/Lightweight Components Mixing feature. This method enables developers to set an arbitrary shape to be cut out from heavyweight components positioned underneath the lightweight component in the z-order.
The shape argument may have the following values:
null - reverts the default cutout shape (the rectangle equal to the component's getBounds())new Rectangle().The most common example when the 'mixing-cutout' shape is needed is a glass pane component. The JRootPane.setGlassPane(java.awt.Component) method automatically sets the empty-shape as the 'mixing-cutout' shape for the given glass pane component. If a developer needs some other 'mixing-cutout' shape for the glass pane (which is rare), this must be changed manually after installing the glass pane to the root pane.
shape - the new 'mixing-cutout' shape
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