ImageObserver
, MenuContainer
, Serializable
BasicSplitPaneDivider
, CellRendererPane
, DefaultTreeCellEditor.EditorContainer
, JComponent
, Panel
, ScrollPane
, Window
public class Container extends Component
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).
Note: For details on the focus subsystem, see How to Use the Focus Subsystem, a section in The Java Tutorial, and the Focus Specification for more information.
Modifier and Type | Class | Description |
---|---|---|
protected class |
Container.AccessibleAWTContainer |
Inner class of Container used to provide default support for accessibility. |
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
Constructor | Description |
---|---|
Container() |
Constructs a new Container. |
Modifier and Type | Method | Description |
---|---|---|
Component |
add |
Appends the specified component to the end of this container. |
Component |
add |
Adds the specified component to this container at the given position. |
void |
add |
Adds the specified component to the end of this container. |
void |
add |
Adds the specified component to this container with the specified constraints at the specified index. |
Component |
add |
Adds the specified component to this container. |
void |
addContainerListener |
Adds the specified container listener to receive container events from this container. |
protected void |
addImpl |
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 |
Adds a PropertyChangeListener to the listener list. |
void |
addPropertyChangeListener |
Adds a PropertyChangeListener to the listener list for a specific property. |
void |
applyComponentOrientation |
Sets the ComponentOrientation property of this container and all components contained within it. |
boolean |
areFocusTraversalKeysSet |
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 |
Deprecated. As of JDK version 1.1, replaced by dispatchEvent(AWTEvent e)
|
void |
doLayout() |
Causes this container to lay out its components. |
Component |
findComponentAt |
Locates the visible child component that contains the specified position. |
Component |
findComponentAt |
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 |
Gets the nth component in this container. |
Component |
getComponentAt |
Locates the component that contains the x,y position. |
Component |
getComponentAt |
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. |
int |
getComponentZOrder |
Returns the z-order index of the component inside the container. |
ContainerListener[] |
getContainerListeners() |
Returns an array of all the container listeners registered on this container. |
Set |
getFocusTraversalKeys |
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. |
<T extends EventListener> |
getListeners |
Returns an array of all the objects currently registered as FooListener s upon this Container . |
Dimension |
getMaximumSize() |
Returns the maximum size of this container. |
Dimension |
getMinimumSize() |
Returns the minimum size of this container. |
Point |
getMousePosition |
Returns the position of the mouse pointer in this Container 's coordinate space if the Container is under the mouse pointer, otherwise returns null . |
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 |
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 |
Returns whether the specified Container is the focus cycle root of this Container's focus traversal cycle. |
final boolean |
isFocusTraversalPolicyProvider() |
Returns whether this container provides focus traversal policy. |
boolean |
isFocusTraversalPolicySet() |
Returns whether the focus traversal policy has been explicitly set for this Container. |
boolean |
isValidateRoot() |
Indicates if this container is a validate root. |
void |
layout() |
Deprecated. As of JDK version 1.1, replaced by doLayout() . |
void |
list |
Prints a listing of this container to the specified output stream. |
void |
list |
Prints out a list, starting at the specified indentation, to the specified print writer. |
Component |
locate |
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 |
Paints the container. |
void |
paintComponents |
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 |
Prints the container. |
void |
printComponents |
Prints each of the components in this container. |
protected void |
processContainerEvent |
Processes container events occurring on this container by dispatching them to any registered ContainerListener objects. |
protected void |
processEvent |
Processes events on this container. |
void |
remove |
Removes the component, specified by index , from this container. |
void |
remove |
Removes the specified component from this container. |
void |
removeAll() |
Removes all the components from this container. |
void |
removeContainerListener |
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 |
setComponentZOrder |
Moves the specified component to the specified z-order index in the container. |
void |
setFocusCycleRoot |
Sets whether this Container is the root of a focus traversal cycle. |
void |
setFocusTraversalKeys |
Sets the focus traversal keys for a given traversal operation for this Container. |
void |
setFocusTraversalPolicy |
Sets the focus traversal policy that will manage keyboard traversal of this Container's children, if this Container is a focus cycle root. |
final void |
setFocusTraversalPolicyProvider |
Sets whether this container will be used to provide focus traversal policy. |
void |
setFont |
Sets the font of this container. |
void |
setLayout |
Sets the layout manager for this container. |
void |
transferFocusDownCycle() |
Transfers the focus down one focus traversal cycle. |
void |
update |
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). |
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, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAccessibleContext, getBackground, getBaseline, getBaselineResizeBehavior, 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, getMousePosition, getMouseWheelListeners, getName, getParent, 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, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, 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, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setMixingCutoutShape, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle
public Container()
public int getComponentCount()
Note: This method should be called under AWT tree lock.
@Deprecated public int countComponents()
public Component getComponent(int n)
Note: This method should be called under AWT tree lock.
n
- the index of the component to get.ArrayIndexOutOfBoundsException
- if the nth value does not exist.public Component[] getComponents()
Note: This method should be called under AWT tree lock.
public Insets getInsets()
A Frame
object, for example, has a top inset that corresponds to the height of the frame's title bar.
@Deprecated public Insets insets()
getInsets()
.public Component add(Component comp)
addImpl(java.awt.Component, java.lang.Object, int)
. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
comp
- the component to be addedNullPointerException
- if comp
is null
public Component add(String name, Component comp)
addImpl(java.awt.Component, java.lang.Object, int)
. This method is obsolete as of 1.1. Please use the method add(Component, Object)
instead.
This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
name
- the name of the component to be addedcomp
- the component to be addedNullPointerException
- if comp
is null
public Component add(Component comp, int index)
addImpl(java.awt.Component, java.lang.Object, int)
. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
comp
- the component to be addedindex
- the position at which to insert the component, or -1
to append the component to the endcomp
NullPointerException
- if comp
is null
IllegalArgumentException
- if index
is invalid (see addImpl(java.awt.Component, java.lang.Object, int)
for details)public void setComponentZOrder(Component comp, int index)
If the component is a child of some other container, it is removed from that container before being added to this container. The important difference between this method and java.awt.Container.add(Component, int)
is that this method doesn't call removeNotify
on the component while removing it from its previous container unless necessary and when allowed by the underlying native windowing system. This way, if the component has the keyboard focus, it maintains the focus when moved to the new position.
This property is guaranteed to apply only to lightweight non-Container
components.
This method changes layout-related information, and therefore, invalidates the component hierarchy.
Note: Not all platforms support changing the z-order of heavyweight components from one container into another without the call to removeNotify
. There is no way to detect whether a platform supports this, so developers shouldn't make any assumptions.
comp
- the component to be movedindex
- the position in the container's list to insert the component, where getComponentCount()
appends to the endNullPointerException
- if comp
is null
IllegalArgumentException
- if comp
is one of the container's parentsIllegalArgumentException
- if index
is not in the range [0, getComponentCount()]
for moving between containers, or not in the range [0, getComponentCount()-1]
for moving inside a containerIllegalArgumentException
- if adding a container to itselfIllegalArgumentException
- if adding a Window
to a containerpublic int getComponentZOrder(Component comp)
comp
- the component being queriednull
or doesn't belong to the containerpublic void add(Component comp, Object constraints)
addImpl(java.awt.Component, java.lang.Object, int)
. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
comp
- the component to be addedconstraints
- an object expressing layout constraints for this componentNullPointerException
- if comp
is null
public void add(Component comp, Object constraints, int index)
addImpl(java.awt.Component, java.lang.Object, int)
. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
comp
- the component to be addedconstraints
- an object expressing layout constraints for thisindex
- the position in the container's list at which to insert the component; -1
means insert at the end componentNullPointerException
- if comp
is null
IllegalArgumentException
- if index
is invalid (see addImpl(java.awt.Component, java.lang.Object, int)
for details)protected void addImpl(Component comp, Object constraints, int index)
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
.
The GridBagLayout
class requires a GridBagConstraints
object. Failure to pass the correct type of constraints object results in an IllegalArgumentException
.
If the current layout manager implements LayoutManager2
, then LayoutManager2.addLayoutComponent(Component,Object)
is invoked on it. If the current layout manager does not implement LayoutManager2
, and constraints is a String
, then LayoutManager.addLayoutComponent(String,Component)
is invoked on it.
If the component is not an ancestor of this container and has a non-null parent, it is removed from its current parent before it is 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)
This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to display the added component.
comp
- the component to be addedconstraints
- an object expressing layout constraints for this componentindex
- the position in the container's list at which to insert the component, where -1
means append to the endIllegalArgumentException
- if index
is invalid; if comp
is a child of this container, the valid range is [-1, getComponentCount()-1]
; if component is not a child of this container, the valid range is [-1, getComponentCount()]
IllegalArgumentException
- if comp
is an ancestor of this containerIllegalArgumentException
- if adding a window to a containerNullPointerException
- if comp
is null
public void remove(int index)
index
, from this container. This method also notifies the layout manager to remove the component from this container's layout via the removeLayoutComponent
method. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to reflect the changes.
index
- the index of the component to be removedArrayIndexOutOfBoundsException
- if index
is not in range [0, getComponentCount()-1]
public void remove(Component comp)
removeLayoutComponent
method. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to reflect the changes.
comp
- the component to be removedNullPointerException
- if comp
is null
public void removeAll()
removeLayoutComponent
method. This method changes layout-related information, and therefore, invalidates the component hierarchy. If the container has already been displayed, the hierarchy must be validated thereafter in order to reflect the changes.
public LayoutManager getLayout()
public void setLayout(LayoutManager mgr)
This method changes layout-related information, and therefore, invalidates the component hierarchy.
mgr
- the specified layout managerpublic void doLayout()
validate
method instead.@Deprecated public void layout()
doLayout()
.public boolean isValidateRoot()
Layout-related changes, such as bounds of the validate root descendants, do not affect the layout of the validate root parent. This peculiarity enables the invalidate()
method to stop invalidating the component hierarchy when the method encounters a validate root. However, to preserve backward compatibility this new optimized behavior is enabled only when the java.awt.smartInvalidate
system property value is set to true
.
If a component hierarchy contains validate roots and the new optimized invalidate()
behavior is enabled, the validate()
method must be invoked on the validate root of a previously invalidated component to restore the validity of the hierarchy later. Otherwise, calling the validate()
method on the top-level container (such as a Frame
object) should be used to restore the validity of the component hierarchy.
The Window
class and the Applet
class are the validate roots in AWT. Swing introduces more validate roots.
public void invalidate()
If the LayoutManager
installed on this container is an instance of the LayoutManager2
interface, then the LayoutManager2.invalidateLayout(Container)
method is invoked on it supplying this Container
as the argument.
Afterwards this method marks this container invalid, and invalidates its ancestors. See the Component.invalidate()
method for more details.
invalidate
in class Component
public void validate()
Validating a container means laying out its subcomponents. Layout-related changes, such as setting the bounds of a component, or adding a component to the container, invalidate the container automatically. Note that the ancestors of the container may be invalidated also (see Component.invalidate()
for details.) Therefore, to restore the validity of the hierarchy, the
validate()
method should be invoked on the top-most invalid container of the hierarchy.
Validating the container may be a quite time-consuming operation. For performance reasons a developer may postpone the validation of the hierarchy till a set of layout-related operations completes, e.g. after adding all the children to the container.
If this Container
is not valid, this method invokes the validateTree
method and marks this Container
as valid. Otherwise, no action is performed.
protected void validateTree()
validate
.public void setFont(Font f)
This method changes layout-related information, and therefore, invalidates the component hierarchy.
public Dimension getPreferredSize()
Component.setPreferredSize(Dimension)
and this Container
has a non-null
LayoutManager
, then LayoutManager.preferredLayoutSize(Container)
is used to calculate the preferred size. Note: some implementations may cache the value returned from the LayoutManager
. Implementations that cache need not invoke preferredLayoutSize
on the LayoutManager
every time this method is invoked, rather the LayoutManager
will only be queried after the Container
becomes invalid.
getPreferredSize
in class Component
Dimension
that represents the preferred size of this container.@Deprecated public Dimension preferredSize()
getPreferredSize()
.Component
preferredSize
in class Component
public Dimension getMinimumSize()
Component.setMinimumSize(Dimension)
and this Container
has a non-null
LayoutManager
, then LayoutManager.minimumLayoutSize(Container)
is used to calculate the minimum size. Note: some implementations may cache the value returned from the LayoutManager
. Implementations that cache need not invoke minimumLayoutSize
on the LayoutManager
every time this method is invoked, rather the LayoutManager
will only be queried after the Container
becomes invalid.
getMinimumSize
in class Component
Dimension
that represents the minimum size of this container.@Deprecated public Dimension minimumSize()
getMinimumSize()
.Component
minimumSize
in class Component
public Dimension getMaximumSize()
Component.setMaximumSize(Dimension)
and the LayoutManager
installed on this Container
is an instance of LayoutManager2
, then LayoutManager2.maximumLayoutSize(Container)
is used to calculate the maximum size. Note: some implementations may cache the value returned from the LayoutManager2
. Implementations that cache need not invoke maximumLayoutSize
on the LayoutManager2
every time this method is invoked, rather the LayoutManager2
will only be queried after the Container
becomes invalid.
getMaximumSize
in class Component
Dimension
that represents the maximum size of this container.public float getAlignmentX()
getAlignmentX
in class Component
public float getAlignmentY()
getAlignmentY
in class Component
public void paint(Graphics g)
public void update(Graphics g)
public void print(Graphics g)
public void paintComponents(Graphics g)
g
- the graphics context.public void printComponents(Graphics g)
g
- the graphics context.public void addContainerListener(ContainerListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the container listenerpublic void removeContainerListener(ContainerListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the container listenerpublic ContainerListener[] getContainerListeners()
ContainerListener
s or an empty array if no container listeners are currently registeredpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListener
s upon this Container
. 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 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.
getListeners
in class Component
T
- the type of the listenerslistenerType
- the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
FooListener
s on this container, or an empty array if no such listeners have been addedClassCastException
- if listenerType
doesn't specify a class or interface that implements java.util.EventListener
NullPointerException
- if listenerType
is null
protected void processEvent(AWTEvent e)
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.
processEvent
in class Component
e
- the eventprotected void processContainerEvent(ContainerEvent e)
addContainerListener
enableEvents
Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
e
- the container event@Deprecated public void deliverEvent(Event e)
dispatchEvent(AWTEvent e)
deliverEvent
in class Component
e
- the event to deliverpublic Component getComponentAt(int x, int y)
getComponentAt
in class Component
x
- the x coordinatey
- the y coordinate@Deprecated public Component locate(int x, int y)
getComponentAt(int, int)
.Component
public Component getComponentAt(Point p)
getComponentAt
in class Component
p
- the point.null
if the component does not contain the point.public Point getMousePosition(boolean allowChildren) throws HeadlessException
Container
's coordinate space if the Container
is under the mouse pointer, otherwise returns null
. This method is similar to Component.getMousePosition()
with the exception that it can take the Container
's children into account. If allowChildren
is false
, this method will return a non-null value only if the mouse pointer is above the Container
directly, not above the part obscured by children. If allowChildren
is true
, this method returns a non-null value if the mouse pointer is above Container
or any of its descendants.allowChildren
- true if children should be taken into accountComponent
, or nullHeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic Component findComponentAt(int x, int y)
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.
x
- the x coordinatey
- the y coordinatepublic Component findComponentAt(Point p)
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.
p
- the point.NullPointerException
- if p
is null
public void addNotify()
public void removeNotify()
removeNotify
in class Component
public boolean isAncestorOf(Component c)
c
- the componenttrue
if it is an ancestor; false
otherwise.protected String paramString()
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
.paramString
in class Component
public void list(PrintStream out, int indent)
The immediate children of the container are printed with an indentation of indent+1
. The children of those children are printed at indent+2
and so on.
list
in class Component
out
- a print streamindent
- the number of spaces to indentNullPointerException
- if out
is null
public void list(PrintWriter out, int indent)
The immediate children of the container are printed with an indentation of indent+1
. The children of those children are printed at indent+2
and so on.
list
in class Component
out
- a print writerindent
- the number of spaces to indentNullPointerException
- if out
is null
public void setFocusTraversalKeys(int id, Set<? extends AWTKeyStroke> keystrokes)
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 |
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.
This method may throw a ClassCastException
if any Object
in keystrokes
is not an AWTKeyStroke
.
setFocusTraversalKeys
in class Component
id
- one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYSkeystrokes
- the Set of AWTKeyStroke for the specified operationIllegalArgumentException
- 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 keystroke represents a KEY_TYPED event, or if any keystroke already maps to another focus traversal operation for this Containerpublic Set<AWTKeyStroke> getFocusTraversalKeys(int id)
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.
getFocusTraversalKeys
in class Component
id
- one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYSIllegalArgumentException
- if id is not one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYSpublic boolean areFocusTraversalKeysSet(int id)
false
, this Container is inheriting the Set from an ancestor, or from the current KeyboardFocusManager.areFocusTraversalKeysSet
in class Component
id
- one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYStrue
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, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYSpublic boolean isFocusCycleRoot(Container container)
true
for both such Containers in this case.isFocusCycleRoot
in class Component
container
- the Container to be testedtrue
if the specified Container is a focus-cycle- root of this Container; false
otherwisepublic void setFocusTraversalPolicy(FocusTraversalPolicy policy)
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.
policy
- the new focus traversal policy for this Containerpublic FocusTraversalPolicy getFocusTraversalPolicy()
public boolean isFocusTraversalPolicySet()
false
, this Container will inherit its focus traversal policy from an ancestor.true
if the focus traversal policy has been explicitly set for this Container; false
otherwise.public void setFocusCycleRoot(boolean focusCycleRoot)
The alternative way to specify the traversal order of this Container's children is to make this Container a focus traversal policy provider.
focusCycleRoot
- indicates whether this Container is the root of a focus traversal cyclepublic boolean isFocusCycleRoot()
public final void setFocusTraversalPolicyProvider(boolean provider)
true
will be used to acquire focus traversal policy instead of closest focus cycle root ancestor.provider
- indicates whether this container will be used to provide focus traversal policypublic final boolean isFocusTraversalPolicyProvider()
true
then when keyboard focus manager searches container hierarchy for focus traversal policy and encounters this container before any other container with this property as true or focus cycle roots then its focus traversal policy will be used instead of focus cycle root's policy.true
if this container provides focus traversal policy, false
otherwisepublic void transferFocusDownCycle()
public void applyComponentOrientation(ComponentOrientation o)
ComponentOrientation
property of this container and all components contained within it. This method changes layout-related information, and therefore, invalidates the component hierarchy.
applyComponentOrientation
in class Component
o
- the new component orientation of this container and the components contained within it.NullPointerException
- if orientation
is null.public void addPropertyChangeListener(PropertyChangeListener listener)
If listener is null, no exception is thrown and no action is performed.
addPropertyChangeListener
in class Component
listener
- the PropertyChangeListener to be addedpublic void addPropertyChangeListener(String propertyName, PropertyChangeListener listener)
If listener is null, no exception is thrown and no action is performed.
addPropertyChangeListener
in class Component
propertyName
- one of the property names listed abovelistener
- the PropertyChangeListener to be added
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/Container.html