JavaTM 2 Platform
Std. Ed. v1.4.2

java.awt
Class Container

java.lang.Object
  extended byjava.awt.Component
      extended byjava.awt.Container
All Implemented Interfaces:
ImageObserver, MenuContainer, Serializable
Direct Known Subclasses:
BasicSplitPaneDivider, CellRendererPane, DefaultTreeCellEditor.EditorContainer, JComponent, Panel, ScrollPane, Window

public class Container
extends Component

A generic Abstract Window Toolkit(AWT) container object is a component that can contain other AWT components.

Components added to a container are tracked in a list. The order of the list will define the components' front-to-back stacking order within the container. If no index is specified when adding a component to a container, it will be added to the end of the list (and hence to the bottom of the stacking order).

Since:
JDK1.0
See Also:
add(java.awt.Component, int), getComponent(int), LayoutManager, Serialized Form

Nested Class Summary
protected  class Container.AccessibleAWTContainer
          Inner class of Container used to provide default support for accessibility.
 
Nested classes inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BltBufferStrategy, Component.FlipBufferStrategy
 
Field Summary
 
Fields inherited from class java.awt.Component
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
 
Fields inherited from interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
 
Constructor Summary
Container()
          Constructs a new Container.
 
Method Summary
 Component add(Component comp)
          Appends the specified component to the end of this container.
 Component add(Component comp, int index)
          Adds the specified component to this container at the given position.
 void add(Component comp, Object constraints)
          Adds the specified component to the end of this container.
 void add(Component comp, Object constraints, int index)
          Adds the specified component to this container with the specified constraints at the specified index.
 Component add(String name, Component comp)
          Adds the specified component to this container.
 void addContainerListener(ContainerListener l)
          Adds the specified container listener to receive container events from this container.
protected  void addImpl(Component comp, Object constraints, int index)
          Adds the specified component to this container at the specified index.
 void addNotify()
          Makes this Container 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 o)
          Sets the ComponentOrientation property of this container 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 Container.
 int countComponents()
          Deprecated. As of JDK version 1.1, replaced by getComponentCount().
 void deliverEvent(Event e)
          Deprecated. As of JDK version 1.1, replaced by dispatchEvent(AWTEvent e)
 void doLayout()
          Causes this container to lay out its components.
 Component findComponentAt(int x, int y)
          Locates the visible child component that contains the specified position.
 Component findComponentAt(Point p)
          Locates the visible child component that contains the specified point.
 float getAlignmentX()
          Returns the alignment along the x axis.
 float getAlignmentY()
          Returns the alignment along the y axis.
 Component getComponent(int n)
          Gets the nth component in this container.
 Component getComponentAt(int x, int y)
          Locates the component that contains the x,y position.
 Component getComponentAt(Point p)
          Gets the component that contains the specified point.
 int getComponentCount()
          Gets the number of components in this panel.
 Component[] getComponents()
          Gets all the components in this container.
 ContainerListener[] getContainerListeners()
          Returns an array of all the container listeners registered on this container.
 Set getFocusTraversalKeys(int id)
          Returns the Set of focus traversal keys for a given traversal operation for this Container.
 FocusTraversalPolicy getFocusTraversalPolicy()
          Returns the focus traversal policy that will manage keyboard traversal of this Container's children, or null if this Container is not a focus cycle root.
 Insets getInsets()
          Determines the insets of this container, which indicate the size of the container's border.
 LayoutManager getLayout()
          Gets the layout manager for this container.
 EventListener[] getListeners(Class listenerType)
          Returns an array of all the objects currently registered as FooListeners upon this Container.
 Dimension getMaximumSize()
          Returns the maximum size of this container.
 Dimension getMinimumSize()
          Returns the minimum size of this container.
 Dimension getPreferredSize()
          Returns the preferred size of this container.
 Insets insets()
          Deprecated. As of JDK version 1.1, replaced by getInsets().
 void invalidate()
          Invalidates the container.
 boolean isAncestorOf(Component c)
          Checks if the component is contained in the component hierarchy of this container.
 boolean isFocusCycleRoot()
          Returns whether this Container is the root of a focus traversal cycle.
 boolean isFocusCycleRoot(Container container)
          Returns whether the specified Container is the focus cycle root of this Container's focus traversal cycle.
 boolean isFocusTraversalPolicySet()
          Returns whether the focus traversal policy has been explicitly set for this Container.
 void layout()
          Deprecated. As of JDK version 1.1, replaced by doLayout().
 void list(PrintStream out, int indent)
          Prints a listing of this container to the specified output stream.
 void list(PrintWriter out, int indent)
          Prints out a list, starting at the specified indention, to the specified print writer.
 Component locate(int x, int y)
          Deprecated. As of JDK version 1.1, replaced by getComponentAt(int, int).
 Dimension minimumSize()
          Deprecated. As of JDK version 1.1, replaced by getMinimumSize().
 void paint(Graphics g)
          Paints the container.
 void paintComponents(Graphics g)
          Paints each of the components in this container.
protected  String paramString()
          Returns a string representing the state of this Container.
 Dimension preferredSize()
          Deprecated. As of JDK version 1.1, replaced by getPreferredSize().
 void print(Graphics g)
          Prints the container.
 void printComponents(Graphics g)
          Prints each of the components in this container.
protected  void processContainerEvent(ContainerEvent e)
          Processes container events occurring on this container by dispatching them to any registered ContainerListener objects.
protected  void processEvent(AWTEvent e)
          Processes events on this container.
 void remove(Component comp)
          Removes the specified component from this container.
 void remove(int index)
          Removes the component, specified by index, from this container.
 void removeAll()
          Removes all the components from this container.
 void removeContainerListener(ContainerListener l)
          Removes the specified container listener so it no longer receives container events from this container.
 void removeNotify()
          Makes this Container undisplayable by removing its connection to its native screen resource.
 void setFocusCycleRoot(boolean focusCycleRoot)
          Sets whether this Container is the root of a focus traversal cycle.
 void setFocusTraversalKeys(int id, Set keystrokes)
          Sets the focus traversal keys for a given traversal operation for this Container.
 void setFocusTraversalPolicy(FocusTraversalPolicy policy)
          Sets the focus traversal policy that will manage keyboard traversal of this Container's children, if this Container is a focus cycle root.
 void setFont(Font f)
          Sets the font of this container.
 void setLayout(LayoutManager mgr)
          Sets the layout manager for this container.
 void transferFocusBackward()
          Transfers the focus to the previous component, as though this Component were the focus owner.
 void transferFocusDownCycle()
          Transfers the focus down one focus traversal cycle.
 void update(Graphics g)
          Updates the container.
 void validate()
          Validates this container and all of its subcomponents.
protected  void validateTree()
          Recursively descends the container tree and recomputes the layout for any subtrees marked as needing it (those marked as invalid).
 
Methods inherited from class java.awt.Component
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, getAccessibleContext, getBackground, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusUpCycle
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Container

public Container()
Constructs a new Container. Containers can be extended directly, but are lightweight in this case and must be contained by a parent somewhere higher up in the component tree that is native. (such as Frame for example).

Method Detail

getComponentCount

public int getComponentCount()
Gets the number of components in this panel.

Returns:
the number of components in this panel.
Since:
JDK1.1
See Also:
getComponent(int)

countComponents

public int countComponents()
Deprecated. As of JDK version 1.1, replaced by getComponentCount().


getComponent

public Component getComponent(int n)
Gets the nth component in this container.

Parameters:
n - the index of the component to get.
Returns:
the nth component in this container.
Throws:
ArrayIndexOutOfBoundsException - if the nth value does not exist.

getComponents

public Component[] getComponents()
Gets all the components in this container.

Returns:
an array of all the components in this container.

getInsets

public Insets getInsets()
Determines the insets of this container, which indicate the size of the container's border.

A Frame object, for example, has a top inset that corresponds to the height of the frame's title bar.

Returns:
the insets of this container.
Since:
JDK1.1
See Also:
Insets, LayoutManager

insets

public Insets insets()
Deprecated. As of JDK version 1.1, replaced by getInsets().


add

public Component add(Component comp)
Appends the specified component to the end of this container. This is a convenience method for addImpl(java.awt.Component, java.lang.Object, int).

Note: If a component has been added to a container that has been displayed, validate must be called on that container to display the new component. If multiple components are being added, you can improve efficiency by calling validate only once, after all the components have been added.

Parameters:
comp - the component to be added
Returns:
the component argument
See Also:
addImpl(java.awt.Component, java.lang.Object, int), validate(), JComponent.revalidate()

add

public Component add(String name,
                     Component comp)
Adds the specified component to this container. This is a convenience method for addImpl(java.awt.Component, java.lang.Object, int).

This method is obsolete as of 1.1. Please use the method add(Component, Object) instead.

See Also:
add(Component, Object)

add

public Component add(Component comp,
                     int index)
Adds the specified component to this container at the given position. This is a convenience method for addImpl(java.awt.Component, java.lang.Object, int).

Note: If a component has been added to a container that has been displayed, validate must be called on that container to display the new component. If multiple components are being added, you can improve efficiency by calling validate only once, after all the components have been added.

Parameters:
comp - the component to be added
index - the position at which to insert the component, or -1 to append the component to the end
Returns:
the component comp
See Also:
addImpl(java.awt.Component, java.lang.Object, int), remove(int), validate(), JComponent.revalidate()

add

public void add(Component comp,
                Object constraints)
Adds the specified component to the end of this container. Also notifies the layout manager to add the component to this container's layout using the specified constraints object. This is a convenience method for addImpl(java.awt.Component, java.lang.Object, int).

Note: If a component has been added to a container that has been displayed, validate must be called on that container to display the new component. If multiple components are being added, you can improve efficiency by calling validate only once, after all the components have been added.

Parameters:
comp - the component to be added
constraints - an object expressing layout contraints for this component
Since:
JDK1.1
See Also:
addImpl(java.awt.Component, java.lang.Object, int), validate(), JComponent.revalidate(), LayoutManager

add

public void add(Component comp,
                Object constraints,
                int index)
Adds the specified component to this container with the specified constraints at the specified index. Also notifies the layout manager to add the component to the this container's layout using the specified constraints object. This is a convenience method for addImpl(java.awt.Component, java.lang.Object, int).

Note: If a component has been added to a container that has been displayed, validate must be called on that container to display the new component. If multiple components are being added, you can improve efficiency by calling validate only once, after all the components have been added.

Parameters:
comp - the component to be added
constraints - an object expressing layout contraints for this
index - the position in the container's list at which to insert the component; -1 means insert at the end component
See Also:
addImpl(java.awt.Component, java.lang.Object, int), validate(), JComponent.revalidate(), remove(int), LayoutManager

addImpl

protected void addImpl(Component comp,
                       Object constraints,
                       int index)
Adds the specified component to this container at the specified index. This method also notifies the layout manager to add the component to this container's layout using the specified constraints object via the addLayoutComponent method. The constraints are defined by the particular layout manager being used. For example, the BorderLayout class defines five constraints: BorderLayout.NORTH, BorderLayout.SOUTH, BorderLayout.EAST, BorderLayout.WEST, and BorderLayout.CENTER.

Note that if the component already exists in this container or a child of this container, it is removed from that container before being added to this container.

This is the method to override if a program needs to track every add request to a container as all other add methods defer to this one. An overriding method should usually include a call to the superclass's version of the method:

super.addImpl(comp, constraints, index)

Parameters:
comp - the component to be added
constraints - an object expressing layout constraints for this component
index - the position in the container's list at which to insert the component, where -1 means append to the end
Throws:
IllegalArgumentException - if index is invalid
IllegalArgumentException - if adding the container's parent to itself
IllegalArgumentException - if adding a window to a container
Since:
JDK1.1
See Also:
add(Component), add(Component, int), add(Component, java.lang.Object), LayoutManager, LayoutManager2

remove

public void remove(int index)
Removes the component, specified by index, from this container.

Parameters:
index - the index of the component to be removed.
Since:
JDK1.1
See Also:
add(java.awt.Component)

remove

public void remove(Component comp)
Removes the specified component from this container.

Parameters:
comp - the component to be removed
See Also:
add(java.awt.Component)

removeAll

public void removeAll()
Removes all the components from this container.

See Also:
add(java.awt.Component), remove(int)

getLayout

public LayoutManager getLayout()
Gets the layout manager for this container.

See Also:
doLayout(), setLayout(java.awt.LayoutManager)

setLayout

public void setLayout(LayoutManager mgr)
Sets the layout manager for this container.

Parameters:
mgr - the specified layout manager
See Also:
doLayout(), getLayout()

doLayout

public void doLayout()
Causes this container to lay out its components. Most programs should not call this method directly, but should invoke the validate method instead.

Overrides:
doLayout in class Component
Since:
JDK1.1
See Also:
LayoutManager.layoutContainer(java.awt.Container), setLayout(java.awt.LayoutManager), validate()

layout

public void layout()
Deprecated. As of JDK version 1.1, replaced by doLayout().

Overrides:
layout in class Component

invalidate

public void invalidate()
Invalidates the container. The container and all parents above it are marked as needing to be laid out. This method can be called often, so it needs to execute quickly.

Overrides:
invalidate in class Component
See Also:
validate(), layout(), LayoutManager

validate

public void validate()
Validates this container and all of its subcomponents.

The validate method is used to cause a container to lay out its subcomponents again. It should be invoked when this container's subcomponents are modified (added to or removed from the container, or layout-related information changed) after the container has been displayed.

Overrides:
validate in class Component
See Also:
add(java.awt.Component), Component.invalidate(), JComponent.revalidate()

validateTree

protected void validateTree()
Recursively descends the container tree and recomputes the layout for any subtrees marked as needing it (those marked as invalid). Synchronization should be provided by the method that calls this one: validate.


setFont

public void setFont(Font f)
Sets the font of this container.

Overrides:
setFont in class Component
Parameters:
f - The font to become this container's font.
Since:
JDK1.0
See Also:
Component.getFont()

getPreferredSize

public Dimension getPreferredSize()
Returns the preferred size of this container.

Overrides:
getPreferredSize in class Component
Returns:
an instance of Dimension that represents the preferred size of this container.
See Also:
getMinimumSize(), getLayout(), LayoutManager.preferredLayoutSize(Container), Component.getPreferredSize()

preferredSize

public Dimension preferredSize()
Deprecated. As of JDK version 1.1, replaced by getPreferredSize().

Overrides:
preferredSize in class Component

getMinimumSize

public Dimension getMinimumSize()
Returns the minimum size of this container.

Overrides:
getMinimumSize in class Component
Returns:
an instance of Dimension that represents the minimum size of this container.
Since:
JDK1.1
See Also:
getPreferredSize(), getLayout(), LayoutManager.minimumLayoutSize(Container), Component.getMinimumSize()

minimumSize

public Dimension minimumSize()
Deprecated. As of JDK version 1.1, replaced by getMinimumSize().

Overrides:
minimumSize in class Component

getMaximumSize

public Dimension getMaximumSize()
Returns the maximum size of this container.

Overrides:
getMaximumSize in class Component
Returns:
a dimension object indicating this component's maximum size
See Also:
getPreferredSize()

getAlignmentX

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.

Overrides:
getAlignmentX in class Component

getAlignmentY

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.

Overrides:
getAlignmentY in class Component

paint

public void paint(Graphics g)
Paints the container. This forwards the paint to any lightweight components that are children of this container. If this method is reimplemented, super.paint(g) should be called so that lightweight components are properly rendered. If a child component is entirely clipped by the current clipping setting in g, paint() will not be forwarded to that child.

Overrides:
paint in class Component
Parameters:
g - the specified Graphics window
See Also:
Component.update(Graphics)

update

public void update(Graphics g)
Updates the container. This forwards the update to any lightweight components that are children of this container. If this method is reimplemented, super.update(g) should be called so that lightweight components are properly rendered. If a child component is entirely clipped by the current clipping setting in g, update() will not be forwarded to that child.

Overrides:
update in class Component
Parameters:
g - the specified Graphics window
See Also:
Component.update(Graphics)

print

public void print(Graphics g)
Prints the container. This forwards the print to any lightweight components that are children of this container. If this method is reimplemented, super.print(g) should be called so that lightweight components are properly rendered. If a child component is entirely clipped by the current clipping setting in g, print() will not be forwarded to that child.

Overrides:
print in class Component
Parameters:
g - the specified Graphics window
See Also:
Component.update(Graphics)

paintComponents

public void paintComponents(Graphics g)
Paints each of the components in this container.

Parameters:
g - the graphics context.
See Also:
Component.paint(java.awt.Graphics), Component.paintAll(java.awt.Graphics)

printComponents

public void printComponents(Graphics g)
Prints each of the components in this container.

Parameters:
g - the graphics context.
See Also:
Component.print(java.awt.Graphics), Component.printAll(java.awt.Graphics)

addContainerListener

public void addContainerListener(ContainerListener l)
Adds the specified container listener to receive container events from this container. If l is null, no exception is thrown and no action is performed.

Parameters:
l - the container listener
See Also:
removeContainerListener(java.awt.event.ContainerListener), getContainerListeners()

removeContainerListener

public void removeContainerListener(ContainerListener l)
Removes the specified container listener so it no longer receives container events from this container. If l is null, no exception is thrown and no action is performed.

Parameters:
l - the container listener
See Also:
addContainerListener(java.awt.event.ContainerListener), getContainerListeners()

getContainerListeners

public ContainerListener[] getContainerListeners()
Returns an array of all the container listeners registered on this container.

Returns:
all of this container's ContainerListeners or an empty array if no container listeners are currently registered
Since:
1.4
See Also:
addContainerListener(java.awt.event.ContainerListener), removeContainerListener(java.awt.event.ContainerListener)

getListeners

public EventListener[] getListeners(Class listenerType)
Returns an array of all the objects currently registered as FooListeners upon this Container. FooListeners 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 Container c for its container listeners with the following code:

ContainerListener[] cls = (ContainerListener[])(c.getListeners(ContainerListener.class));
If no such listeners exist, this method returns an empty array.

Overrides:
getListeners in class Component
Parameters:
listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
Returns:
an array of all objects registered as FooListeners on this container, or an empty array if no such listeners have been added
Throws:
ClassCastException - if listenerType doesn't specify a class or interface that implements java.util.EventListener
Since:
1.3
See Also:
getContainerListeners()

processEvent

protected void processEvent(AWTEvent e)
Processes events on this container. If the event is a ContainerEvent, it invokes the processContainerEvent method, else it invokes its superclass's processEvent.

Note that if the event parameter is null the behavior is unspecified and may result in an exception.

Overrides:
processEvent in class Component
Parameters:
e - the event
See Also:
Component.processComponentEvent(java.awt.event.ComponentEvent), Component.processFocusEvent(java.awt.event.FocusEvent), Component.processKeyEvent(java.awt.event.KeyEvent), Component.processMouseEvent(java.awt.event.MouseEvent), Component.processMouseMotionEvent(java.awt.event.MouseEvent), Component.processInputMethodEvent(java.awt.event.InputMethodEvent), Component.processHierarchyEvent(java.awt.event.HierarchyEvent), Component.processMouseWheelEvent(java.awt.event.MouseWheelEvent)

processContainerEvent

protected void processContainerEvent(ContainerEvent e)
Processes container events occurring on this container by dispatching them to any registered ContainerListener objects. NOTE: This method will not be called unless container events are enabled for this component; this happens when one of the following occurs:

Note that if the event parameter is null the behavior is unspecified and may result in an exception.

Parameters:
e - the container event
See Also:
Component.enableEvents(long)

deliverEvent

public void deliverEvent(Event e)
Deprecated. As of JDK version 1.1, replaced by dispatchEvent(AWTEvent e)

Overrides:
deliverEvent in class Component

getComponentAt

public Component getComponentAt(int x,
                                int y)
Locates the component that contains the x,y position. The top-most child component is returned in the case where there is overlap in the components. This is determined by finding the component closest to the index 0 that claims to contain the given point via Component.contains(), except that Components which have native peers take precedence over those which do not (i.e., lightweight Components).

Overrides:
getComponentAt in class Component
Parameters:
x - the x coordinate
y - the y coordinate
Returns:
null if the component does not contain the position. If there is no child component at the requested point and the point is within the bounds of the container the container itself is returned; otherwise the top-most child is returned.
Since:
JDK1.1
See Also:
Component.contains(int, int)

locate

public Component locate(int x,
                        int y)
Deprecated. As of JDK version 1.1, replaced by getComponentAt(int, int).

Overrides:
locate in class Component

getComponentAt

public Component getComponentAt(Point p)
Gets the component that contains the specified point.

Overrides:
getComponentAt in class Component
Parameters:
p - the point.
Returns:
returns the component that contains the point, or null if the component does not contain the point.
Since:
JDK1.1
See Also:
Component.contains(int, int)

findComponentAt

public Component findComponentAt(int x,
                                 int y)
Locates the visible child component that contains the specified position. The top-most child component is returned in the case where there is overlap in the components. If the containing child component is a Container, this method will continue searching for the deepest nested child component. Components which are not visible are ignored during the search.

The findComponentAt method is different from getComponentAt in that getComponentAt only searches the Container's immediate children; if the containing component is a Container, findComponentAt will search that child to find a nested component.

Parameters:
x - the x coordinate
y - the y coordinate
Returns:
null if the component does not contain the position. If there is no child component at the requested point and the point is within the bounds of the container the container itself is returned.
Since:
1.2
See Also:
Component.contains(int, int), getComponentAt(int, int)

findComponentAt

public Component findComponentAt(Point p)
Locates the visible child component that contains the specified point. The top-most child component is returned in the case where there is overlap in the components. If the containing child component is a Container, this method will continue searching for the deepest nested child component. Components which are not visible are ignored during the search.

The findComponentAt method is different from getComponentAt in that getComponentAt only searches the Container's immediate children; if the containing component is a Container, findComponentAt will search that child to find a nested component.

Parameters:
p - the point.
Returns:
null if the component does not contain the position. If there is no child component at the requested point and the point is within the bounds of the container the container itself is returned.
Since:
1.2
See Also:
Component.contains(int, int), getComponentAt(int, int)

addNotify

public void addNotify()
Makes this Container displayable by connecting it to a native screen resource. Making a container displayable will cause all of its children to be made displayable. This method is called internally by the toolkit and should not be called directly by programs.

Overrides:
addNotify in class Component
See Also:
Component.isDisplayable(), removeNotify()

removeNotify

public void removeNotify()
Makes this Container undisplayable by removing its connection to its native screen resource. Making a container undisplayable will cause all of its children to be made undisplayable. This method is called by the toolkit internally and should not be called directly by programs.

Overrides:
removeNotify in class Component
See Also:
Component.isDisplayable(), addNotify()

isAncestorOf

public boolean isAncestorOf(Component c)
Checks if the component is contained in the component hierarchy of this container.

Parameters:
c - the component
Returns:
true if it is an ancestor; false otherwise.
Since:
JDK1.1

paramString

protected String paramString()
Returns a string representing the state of this Container. 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.

Overrides:
paramString in class Component
Returns:
the parameter string of this container

list

public void list(PrintStream out,
                 int indent)
Prints a listing of this container to the specified output stream. The listing starts at the specified indentation.

Overrides:
list in class Component
Parameters:
out - a print stream.
indent - the number of spaces to indent.
Since:
JDK1.0
See Also:
Component.list(java.io.PrintStream, int)

list

public void list(PrintWriter out,
                 int indent)
Prints out a list, starting at the specified indention, to the specified print writer.

Overrides:
list in class Component
Parameters:
out - the print writer to print to
indent - the number of spaces to indent
See Also:
PrintStream.println(java.lang.Object)

setFocusTraversalKeys

public void setFocusTraversalKeys(int id,
                                  Set keystrokes)
Sets the focus traversal keys for a given traversal operation for this Container.

The default values for a Container'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.

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 none
KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS Go down one focus traversal cycle none
To 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 Container. 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 Container inherits the Set from its parent. If all ancestors of this Container have null specified for the Set, then the current KeyboardFocusManager's default Set is used.

Overrides:
setFocusTraversalKeys in class Component
Parameters:
id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
keystrokes - the Set of AWTKeyStroke for the specified operation
Throws:
IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS, or if keystrokes contains null, or if any Object in keystrokes is not an AWTKeyStroke, or if any keystroke represents a KEY_TYPED event, or if any keystroke already maps to another focus traversal operation for this Container
Since:
1.4
See Also:
getFocusTraversalKeys(int), KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS

getFocusTraversalKeys

public Set getFocusTraversalKeys(int id)
Returns the Set of focus traversal keys for a given traversal operation for this Container. (See setFocusTraversalKeys for a full description of each key.)

If a Set of traversal keys has not been explicitly defined for this Container, then this Container's parent's Set is returned. If no Set has been explicitly defined for any of this Container's ancestors, then the current KeyboardFocusManager's default Set is returned.

Overrides:
getFocusTraversalKeys in class Component
Parameters:
id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
Returns:
the Set of AWTKeyStrokes for the specified operation. The Set will be unmodifiable, and may be empty. null will never be returned.
Throws:
IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
Since:
1.4
See Also:
setFocusTraversalKeys(int, java.util.Set), KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS

areFocusTraversalKeysSet

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 Container. If this method returns false, this Container is inheriting the Set from an ancestor, or from the current KeyboardFocusManager.

Overrides:
areFocusTraversalKeysSet in class Component
Parameters:
id - one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
Returns:
true if the the Set of focus traversal keys for the given focus traversal operation has been explicitly defined for this Component; false otherwise.
Throws:
IllegalArgumentException - if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS
Since:
1.4

isFocusCycleRoot

public boolean isFocusCycleRoot(Container container)
Returns whether the specified Container is the focus cycle root of this Container's focus traversal cycle. Each focus traversal cycle has only a single focus cycle root and each Container which is not a focus cycle root 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. This method will return true for both such Containers in this case.

Overrides:
isFocusCycleRoot in class Component
Parameters:
container - the Container to be tested
Returns:
true if the specified Container is a focus-cycle- root of this Container; false otherwise
Since:
1.4
See Also:
isFocusCycleRoot()

transferFocusBackward

public void transferFocusBackward()
Description copied from class: Component
Transfers the focus to the previous component, as though this Component were the focus owner.

Overrides:
transferFocusBackward in class Component
See Also:
Component.requestFocus()

setFocusTraversalPolicy

public void setFocusTraversalPolicy(FocusTraversalPolicy policy)
Sets the focus traversal policy that will manage keyboard traversal of this Container's children, if this Container is a focus cycle root. If the argument is null, this Container inherits its policy from its focus- cycle-root ancestor. If the argument is non-null, this policy will be inherited by all focus-cycle-root children that have no keyboard- traversal policy of their own (as will, recursively, their focus-cycle- root children).

If this Container is not a focus cycle root, the policy will be remembered, but will not be used or inherited by this or any other Containers until this Container is made a focus cycle root.

Parameters:
policy - the new focus traversal policy for this Container
Since:
1.4
See Also:
getFocusTraversalPolicy(), setFocusCycleRoot(boolean), isFocusCycleRoot(java.awt.Container)

getFocusTraversalPolicy

public FocusTraversalPolicy getFocusTraversalPolicy()
Returns the focus traversal policy that will manage keyboard traversal of this Container's children, or null if this Container is not a focus cycle root. If no traversal policy has been explicitly set for this Container, then this Container's focus-cycle-root ancestor's policy is returned.

Returns:
this Container's focus traversal policy, or null if this Container is not a focus cycle root.
Since:
1.4
See Also:
setFocusTraversalPolicy(java.awt.FocusTraversalPolicy), setFocusCycleRoot(boolean), isFocusCycleRoot(java.awt.Container)

isFocusTraversalPolicySet

public boolean isFocusTraversalPolicySet()
Returns whether the focus traversal policy has been explicitly set for this Container. If this method returns false, this Container will inherit its focus traversal policy from an ancestor.

Returns:
true if the focus traversal policy has been explicitly set for this Container; false otherwise.
Since:
1.4

setFocusCycleRoot

public void setFocusCycleRoot(boolean focusCycleRoot)
Sets whether this Container is the root of a focus traversal cycle. Once focus enters a traversal cycle, typically it cannot leave it via focus traversal unless one of the up- or down-cycle keys is pressed. Normal traversal is limited to this Container, and all of this Container's descendants that are not descendants of inferior focus cycle roots. Note that a FocusTraversalPolicy may bend these restrictions, however. For example, ContainerOrderFocusTraversalPolicy supports implicit down-cycle traversal.

Parameters:
focusCycleRoot - indicates whether this Container is the root of a focus traversal cycle
Since:
1.4
See Also:
isFocusCycleRoot(), setFocusTraversalPolicy(java.awt.FocusTraversalPolicy), getFocusTraversalPolicy(), ContainerOrderFocusTraversalPolicy

isFocusCycleRoot

public boolean isFocusCycleRoot()
Returns whether this Container is the root of a focus traversal cycle. Once focus enters a traversal cycle, typically it cannot leave it via focus traversal unless one of the up- or down-cycle keys is pressed. Normal traversal is limited to this Container, and all of this Container's descendants that are not descendants of inferior focus cycle roots. Note that a FocusTraversalPolicy may bend these restrictions, however. For example, ContainerOrderFocusTraversalPolicy supports implicit down-cycle traversal.

Returns:
whether this Container is the root of a focus traversal cycle
Since:
1.4
See Also:
setFocusCycleRoot(boolean), setFocusTraversalPolicy(java.awt.FocusTraversalPolicy), getFocusTraversalPolicy(), ContainerOrderFocusTraversalPolicy

transferFocusDownCycle

public void transferFocusDownCycle()
Transfers the focus down one focus traversal cycle. If this Container is a focus cycle root, then the focus owner is set to this Container's default Component to focus, and the current focus cycle root is set to this Container. If this Container is not a focus cycle root, then no focus traversal operation occurs.

Since:
1.4
See Also:
Component.requestFocus(), isFocusCycleRoot(java.awt.Container), setFocusCycleRoot(boolean)

applyComponentOrientation

public void applyComponentOrientation(ComponentOrientation o)
Sets the ComponentOrientation property of this container and all components contained within it.

Overrides:
applyComponentOrientation in class Component
Parameters:
o - the new component orientation of this container and the components contained within it.
Throws:
NullPointerException - if orientation is null.
Since:
1.4
See Also:
Component.setComponentOrientation(java.awt.ComponentOrientation), Component.getComponentOrientation()

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)
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 Container 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.

Overrides:
addPropertyChangeListener in class Component
Parameters:
listener - the PropertyChangeListener to be added
See Also:
Component.removePropertyChangeListener(java.beans.PropertyChangeListener), addPropertyChangeListener(java.lang.String,java.beans.PropertyChangeListener)

addPropertyChangeListener

public void addPropertyChangeListener(String propertyName,
                                      PropertyChangeListener listener)
Adds a PropertyChangeListener to the listener list for a specific property. The specified property may be user-defined, or one of the following defaults: Note that if this Container 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.

Overrides:
addPropertyChangeListener in class Component
Parameters:
propertyName - one of the property names listed above
listener - the PropertyChangeListener to be added
See Also:
addPropertyChangeListener(java.beans.PropertyChangeListener), Component.removePropertyChangeListener(java.beans.PropertyChangeListener)

JavaTM 2 Platform
Std. Ed. v1.4.2

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.


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