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java.awt

Class Container

Implemented Interfaces:
ImageObserver, MenuContainer, Serializable
Known Direct Subclasses:
BasicSplitPaneDivider, CellRendererPane, DefaultTreeCellEditor.EditorContainer, JComponent, Panel, ScrollPane, Window
public class Container
extends Component
A generic window toolkit object that acts as a container for other objects. Components are tracked in a list, and new elements are at the end of the list or bottom of the stacking order.
Since:
1.0
See Also:
Serialized Form

Nested Class Summary

protected class
Container.AccessibleAWTContainer
This class provides accessibility support for subclasses of container.

Nested classes/interfaces 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()
Default constructor for subclasses.

Method Summary

Component
add(Component comp)
Adds the specified component to this container at the end of the component list.
Component
add(Component comp, int index)
Adds the specified component to this container at the specified index in the component list.
void
add(Component comp, Object constraints)
Adds the specified component to this container at the end of the component list.
void
add(Component comp, Object constraints, int index)
Adds the specified component to this container at the specified index in the component list.
Component
add(String name, Component comp)
Adds the specified component to the container at the end of the component list.
void
addContainerListener(ContainerListener listener)
Adds the specified container listener to this object's list of container listeners.
protected void
addImpl(Component comp, Object constraints, int index)
This method is called by all the add() methods to perform the actual adding of the component.
void
addNotify()
Called when this container is added to another container to inform it to create its peer.
void
addPropertyChangeListener(PropertyChangeListener listener)
Adds the specified property listener to this component.
void
addPropertyChangeListener(String propertyName, PropertyChangeListener listener)
Adds the specified property listener to this component.
void
applyComponentOrientation(ComponentOrientation orientation)
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. use getComponentCount() instead
void
deliverEvent(Event e)
Deprecated. use dispatchEvent(AWTEvent) instead
void
doLayout()
Layout the components in this container.
extends EventListener> T[] getListeners(Class listenerType)
Returns all registered EventListeners of the given listenerType.
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 position.
float
getAlignmentX()
Returns the preferred alignment along the X axis.
float
getAlignmentY()
Returns the preferred alignment along the Y axis.
Component
getComponent(int n)
Returns the component at the specified index.
Component
getComponentAt(int x, int y)
Returns the component located at the specified point.
Component
getComponentAt(Point p)
Returns the component located at the specified point.
int
getComponentCount()
Returns the number of components in this container.
int
getComponentZOrder(Component comp)
Returns the Z ordering index of comp.
Component[]
getComponents()
Returns an array of the components in this container.
ContainerListener[]
getContainerListeners()
Set
getFocusTraversalKeys(int id)
Returns the Set of focus traversal keys for a given traversal operation for this Container.
FocusTraversalPolicy
getFocusTraversalPolicy()
Return the focus traversal policy that determines the focus traversal order for this Container's children.
Insets
getInsets()
Returns the insets for this container, which is the space used for borders, the margin, etc.
LayoutManager
getLayout()
Returns the current layout manager for this container.
Dimension
getMaximumSize()
Returns the maximum size of this container.
Dimension
getMinimumSize()
Returns the minimum size of this container.
Point
getMousePosition(boolean allowChildren)
Returns the mouse pointer position relative to this Container's top-left corner.
Dimension
getPreferredSize()
Returns the preferred size of this container.
Insets
insets()
Deprecated. use getInsets() instead
void
invalidate()
Invalidates this container to indicate that it (and all parent containers) need to be laid out.
boolean
isAncestorOf(Component comp)
Tests whether or not the specified component is contained within this components subtree.
boolean
isFocusCycleRoot()
Check whether this Container is a focus cycle root.
boolean
isFocusCycleRoot(Container c)
Check whether the given Container is the focus cycle root of this Container's focus traversal cycle.
boolean
isFocusTraversalPolicyProvider()
Set to true if this container provides a focus traversal policy, false when the root container's focus traversal policy should be used.
boolean
isFocusTraversalPolicySet()
Check whether this Container's focus traversal policy has been explicitly set.
void
layout()
Deprecated. use doLayout() instead
void
list(PrintStream out, int indent)
Writes a listing of this container to the specified stream starting at the specified indentation point.
void
list(PrintWriter out, int indent)
Writes a listing of this container to the specified stream starting at the specified indentation point.
Component
locate(int x, int y)
Deprecated. use getComponentAt(int,int) instead
Dimension
minimumSize()
Deprecated. use getMinimumSize() instead
void
paint(Graphics g)
Paints this container.
void
paintComponents(Graphics g)
Paints all of the components in this container.
protected String
paramString()
Returns a string representing the state of this container for debugging purposes.
Dimension
preferredSize()
Deprecated. use getPreferredSize() instead
void
print(Graphics g)
Prints this container.
void
printComponents(Graphics g)
Prints all of the components in this container.
protected void
processContainerEvent(ContainerEvent e)
Called when a container event occurs if container events are enabled.
protected void
processEvent(AWTEvent e)
Processes the specified event.
void
remove(int index)
Removes the component at the specified index from this container.
void
remove(Component comp)
Removes the specified component from this container.
void
removeAll()
Removes all components from this container.
void
removeContainerListener(ContainerListener listener)
Removes the specified container listener from this object's list of container listeners.
void
removeNotify()
Called when this container is removed from its parent container to inform it to destroy its peer.
void
setComponentZOrder(Component comp, int index)
Sets the Z ordering for the component comp to index.
void
setFocusCycleRoot(boolean focusCycleRoot)
Set whether or not this Container is the root of a focus traversal cycle.
void
setFocusTraversalKeys(int id, AWTKeyStroke> keystrokes)
Sets the focus traversal keys for a given traversal operation for this Container.
void
setFocusTraversalPolicy(FocusTraversalPolicy policy)
If this Container is a focus cycle root, set the focus traversal policy that determines the focus traversal order for its children.
void
setFocusTraversalPolicyProvider(boolean b)
Set to true if this container provides a focus traversal policy, false when the root container's focus traversal policy should be used.
void
setFont(Font f)
Sets the font for this component to the specified font.
void
setLayout(LayoutManager mgr)
Sets the layout manager for this container to the specified layout manager.
void
transferFocusDownCycle()
Transfer focus down one focus traversal cycle.
void
update(Graphics g)
Updates this container.
void
validate()
Re-lays out the components in this container.
protected void
validateTree()
Recursively validates the container tree, recomputing any invalid layouts.

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addNotify, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, extends EventListener> T[] getListeners, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAccessibleContext, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPreferredSize, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFocusable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, paramString, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFocusable, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Container

public Container()
Default constructor for subclasses.

Method Details

add

public Component add(Component comp)
Adds the specified component to this container at the end of the component list.
Parameters:
comp - The component to add to the container.
Returns:
The same component that was added.

add

public Component add(Component comp,
                     int index)
Adds the specified component to this container at the specified index in the component list.
Parameters:
comp - The component to be added.
index - The index in the component list to insert this child at, or -1 to add at the end of the list.
Returns:
The same component that was added.
Throws:
ArrayIndexOutOfBoundsException - If the specified index is invalid.

add

public void add(Component comp,
                Object constraints)
Adds the specified component to this container at the end of the component list. The layout manager will use the specified constraints when laying out this component.
Parameters:
comp - The component to be added to this container.
constraints - The layout constraints for this component.

add

public void add(Component comp,
                Object constraints,
                int index)
Adds the specified component to this container at the specified index in the component list. The layout manager will use the specified constraints when layout out this component.
Parameters:
comp - The component to be added.
constraints - The layout constraints for this component.
index - The index in the component list to insert this child at, or -1 to add at the end of the list.
Throws:
ArrayIndexOutOfBoundsException - If the specified index is invalid.

add

public Component add(String name,
                     Component comp)
Adds the specified component to the container at the end of the component list. This method should not be used. Instead, use add(Component, Object).
Parameters:
name - The name of the component to be added.
comp - The component to be added.
Returns:
The same component that was added.
See Also:
add(Component,Object)

addContainerListener

public void addContainerListener(ContainerListener listener)
Adds the specified container listener to this object's list of container listeners.
Parameters:
listener - The listener to add.

addImpl

protected void addImpl(Component comp,
                       Object constraints,
                       int index)
This method is called by all the add() methods to perform the actual adding of the component. Subclasses who wish to perform their own processing when a component is added should override this method. Any subclass doing this must call the superclass version of this method in order to ensure proper functioning of the container.
Parameters:
comp - The component to be added.
constraints - The layout constraints for this component, or null if there are no constraints.
index - The index in the component list to insert this child at, or -1 to add at the end of the list.
Throws:
ArrayIndexOutOfBoundsException - If the specified index is invalid.

addNotify

public void addNotify()
Called when this container is added to another container to inform it to create its peer. Peers for any child components will also be created.
Overrides:
addNotify in interface Component

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)
Adds the specified property listener to this component. This is harmless if the listener is null, but if the listener has already been registered, it will now be registered twice. The property listener ignores inherited properties. Recognized properties include:
  • the font ("font")
  • the background color ("background")
  • the foreground color ("foreground")
  • the focusability ("focusable")
  • the focus key traversal enabled state ("focusTraversalKeysEnabled")
  • the set of forward traversal keys ("forwardFocusTraversalKeys")
  • the set of backward traversal keys ("backwardFocusTraversalKeys")
  • the set of up-cycle traversal keys ("upCycleFocusTraversalKeys")
Overrides:
addPropertyChangeListener in interface Component
Parameters:
listener - the new listener to add
Since:
1.1
See Also:
Component.removePropertyChangeListener(PropertyChangeListener), Component.getPropertyChangeListeners(), Component.addPropertyChangeListener(String,PropertyChangeListener)

addPropertyChangeListener

public void addPropertyChangeListener(String propertyName,
                                      PropertyChangeListener listener)
Adds the specified property listener to this component. This is harmless if the listener is null, but if the listener has already been registered, it will now be registered twice. The property listener ignores inherited properties. The listener is keyed to a single property. Recognized properties include:
  • the font ("font")
  • the background color ("background")
  • the foreground color ("foreground")
  • the focusability ("focusable")
  • the focus key traversal enabled state ("focusTraversalKeysEnabled")
  • the set of forward traversal keys ("forwardFocusTraversalKeys")
  • the set of backward traversal keys ("backwardFocusTraversalKeys")
  • the set of up-cycle traversal keys ("upCycleFocusTraversalKeys")
Overrides:
addPropertyChangeListener in interface Component
Parameters:
propertyName - the property name to filter on
listener - the new listener to add
Since:
1.1
See Also:
Component.removePropertyChangeListener(String,PropertyChangeListener), Component.getPropertyChangeListeners(String), Component.addPropertyChangeListener(PropertyChangeListener)

applyComponentOrientation

public void applyComponentOrientation(ComponentOrientation orientation)
Sets the ComponentOrientation property of this container and all components contained within it.
Overrides:
applyComponentOrientation in interface Component
Throws:
NullPointerException - If orientation is null
Since:
1.4

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 interface Component
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

countComponents

public int countComponents()

Deprecated. use getComponentCount() instead

Returns the number of components in this container.
Returns:
The number of components in this container.

deliverEvent

public void deliverEvent(Event e)

Deprecated. use dispatchEvent(AWTEvent) instead

AWT 1.0 event processor.
Overrides:
deliverEvent in interface Component
Parameters:
e - The event that occurred.

doLayout

public void doLayout()
Layout the components in this container.
Overrides:
doLayout in interface Component

extends EventListener> T[] getListeners

public extends EventListener> T[] getListeners(Class listenerType)
Returns all registered EventListeners of the given listenerType.
Overrides:
extends EventListener> T[] getListeners in interface Component
Parameters:
listenerType - the class of listeners to filter (null not permitted).
Returns:
An array of registered listeners.
Throws:
ClassCastException - if listenerType does not implement the EventListener interface.
NullPointerException - if listenerType is null.
Since:
1.3
See Also:
getContainerListeners()

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. findComponentAt differs from getComponentAt, because it recursively searches a Container's children.
Parameters:
x - - x coordinate
y - - 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.

findComponentAt

public Component findComponentAt(Point p)
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. findComponentAt differs from getComponentAt, because it recursively searches a Container's children.
Parameters:
p - - the component's location
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.

getAlignmentX

public float getAlignmentX()
Returns the preferred alignment along the X axis. This is a value between 0 and 1 where 0 represents alignment flush left and 1 means alignment flush right, and 0.5 means centered.
Overrides:
getAlignmentX in interface Component
Returns:
The preferred alignment along the X axis.

getAlignmentY

public float getAlignmentY()
Returns the preferred alignment along the Y axis. This is a value between 0 and 1 where 0 represents alignment flush top and 1 means alignment flush bottom, and 0.5 means centered.
Overrides:
getAlignmentY in interface Component
Returns:
The preferred alignment along the Y axis.

getComponent

public Component getComponent(int n)
Returns the component at the specified index.
Parameters:
n - The index of the component to retrieve.
Returns:
The requested component.
Throws:
ArrayIndexOutOfBoundsException - If the specified index is invalid

getComponentAt

public Component getComponentAt(int x,
                                int y)
Returns the component located at the specified point. This is done by checking whether or not a child component claims to contain this point. The first child component that does is returned. If no child component claims the point, the container itself is returned, unless the point does not exist within this container, in which case null is returned. When components overlap, the first component is returned. The component that is closest to (x, y), containing that location, is returned. Heavyweight components take precedence of lightweight components. This function does not ignore invisible components. If there is an invisible component at (x,y), it will be returned.
Overrides:
getComponentAt in interface Component
Parameters:
x - The X coordinate of the point.
y - The Y coordinate of the point.
Returns:
The component containing the specified point, or null if there is no such point.

getComponentAt

public Component getComponentAt(Point p)
Returns the component located at the specified point. This is done by checking whether or not a child component claims to contain this point. The first child component that does is returned. If no child component claims the point, the container itself is returned, unless the point does not exist within this container, in which case null is returned. The top-most child component is returned in the case where components overlap. This is determined by finding the component closest to (x,y) and contains that location. Heavyweight components take precedence of lightweight components. This function does not ignore invisible components. If there is an invisible component at (x,y), it will be returned.
Overrides:
getComponentAt in interface Component
Parameters:
p - The point to return the component at.
Returns:
The component containing the specified point, or null if there is no such point.

getComponentCount

public int getComponentCount()
Returns the number of components in this container.
Returns:
The number of components in this container.

getComponentZOrder

public final int getComponentZOrder(Component comp)
Returns the Z ordering index of comp. If comp is not a child component of this Container, this returns -1.
Parameters:
comp - the component for which to query the Z ordering
Returns:
the Z ordering index of comp or -1 if comp is not a child of this Container
Since:
1.5
See Also:
setComponentZOrder(Component,int)

getComponents

public Component[] getComponents()
Returns an array of the components in this container.
Returns:
The components in this container.

getContainerListeners

public ContainerListener[] getContainerListeners()
Since:
1.4

getFocusTraversalKeys

public Set getFocusTraversalKeys(int id)
Returns the Set of focus traversal keys for a given traversal operation for this Container.
Overrides:
getFocusTraversalKeys in interface Component
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

getFocusTraversalPolicy

public FocusTraversalPolicy getFocusTraversalPolicy()
Return the focus traversal policy that determines the focus traversal order for this Container's children. This method returns null if this Container is not a focus cycle root. If the focus traversal policy has not been set explicitly, then this method will return an ancestor focus cycle root's policy instead.
Returns:
this Container's focus traversal policy or null
Since:
1.4

getInsets

public Insets getInsets()
Returns the insets for this container, which is the space used for borders, the margin, etc.
Returns:
The insets for this container.

getLayout

public LayoutManager getLayout()
Returns the current layout manager for this container.
Returns:
The layout manager for this container.

getMaximumSize

public Dimension getMaximumSize()
Returns the maximum size of this container.
Overrides:
getMaximumSize in interface Component
Returns:
The maximum size of this container.

getMinimumSize

public Dimension getMinimumSize()
Returns the minimum size of this container.
Overrides:
getMinimumSize in interface Component
Returns:
The minimum size of this container.

getMousePosition

public Point getMousePosition(boolean allowChildren)
            throws HeadlessException
Returns the mouse pointer position relative to this Container's top-left corner. If allowChildren is false, the mouse pointer must be directly over this container. If allowChildren is true, the mouse pointer may be over this container or any of its descendents.
Parameters:
allowChildren - true to allow descendents, false if pointer must be directly over Container.
Returns:
relative mouse pointer position
Throws:
HeadlessException - if in a headless environment

getPreferredSize

public Dimension getPreferredSize()
Returns the preferred size of this container.
Overrides:
getPreferredSize in interface Component
Returns:
The preferred size of this container.

insets

public Insets insets()

Deprecated. use getInsets() instead

Returns the insets for this container, which is the space used for borders, the margin, etc.
Returns:
The insets for this container.

invalidate

public void invalidate()
Invalidates this container to indicate that it (and all parent containers) need to be laid out.
Overrides:
invalidate in interface Component

isAncestorOf

public boolean isAncestorOf(Component comp)