java.lang.Object | ||
↳ | java.awt.Component | |
↳ | java.awt.Container |
Known Direct Subclasses |
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).
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.
Nested Classes | |||||||||||
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Container.AccessibleAWTContainer | Inner class of Container used to provide default support for accessibility. |
[Expand]
Inherited Constants | |||||||||||
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From class
java.awt.Component
| |||||||||||
From interface
java.awt.image.ImageObserver
|
Public Constructors | |||||||||||
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Constructs a new Container.
|
Public Methods | |||||||||||
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Adds the specified component to the end of this container.
| |||||||||||
Adds the specified component to this container.
| |||||||||||
Adds the specified component to this container at the given
position.
| |||||||||||
Appends the specified component to the end of this container.
| |||||||||||
Adds the specified component to this container with the specified
constraints at the specified index.
| |||||||||||
Adds the specified container listener to receive container events
from this container.
| |||||||||||
Makes this Container displayable by connecting it to
a native screen resource.
| |||||||||||
Adds a PropertyChangeListener to the listener list for a specific
property.
| |||||||||||
Adds a PropertyChangeListener to the listener list.
| |||||||||||
Sets the
ComponentOrientation property of this container
and all components contained within it. | |||||||||||
Returns whether the Set of focus traversal keys for the given focus
traversal operation has been explicitly defined for this Container.
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by getComponentCount().
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by
dispatchEvent(AWTEvent e)
| |||||||||||
Causes this container to lay out its components.
| |||||||||||
Locates the visible child component that contains the specified
point.
| |||||||||||
Locates the visible child component that contains the specified
position.
| |||||||||||
Returns the alignment along the x axis.
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Returns the alignment along the y axis.
| |||||||||||
Gets the nth component in this container.
| |||||||||||
Locates the component that contains the x,y position.
| |||||||||||
Gets the component that contains the specified point.
| |||||||||||
Gets the number of components in this panel.
| |||||||||||
Returns the z-order index of the component inside the container.
| |||||||||||
Gets all the components in this container.
| |||||||||||
Returns an array of all the container listeners
registered on this container.
| |||||||||||
Returns the Set of focus traversal keys for a given traversal operation
for this Container.
| |||||||||||
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.
| |||||||||||
Determines the insets of this container, which indicate the size
of the container's border.
| |||||||||||
Gets the layout manager for this container.
| |||||||||||
Returns an array of all the objects currently registered
as
FooListener s
upon this Container . | |||||||||||
Returns the maximum size of this container.
| |||||||||||
Returns the minimum size of this container.
| |||||||||||
Returns the position of the mouse pointer in this
Container 's
coordinate space if the Container is under the mouse pointer,
otherwise returns null . | |||||||||||
Returns the preferred size of this container.
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by
getInsets() .
| |||||||||||
Invalidates the container.
| |||||||||||
Checks if the component is contained in the component hierarchy of
this container.
| |||||||||||
Returns whether the specified Container is the focus cycle root of this
Container's focus traversal cycle.
| |||||||||||
Returns whether this Container is the root of a focus traversal cycle.
| |||||||||||
Returns whether this container provides focus traversal
policy.
| |||||||||||
Returns whether the focus traversal policy has been explicitly set for
this Container.
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by
doLayout() .
| |||||||||||
Prints a listing of this container to the specified output
stream.
| |||||||||||
Prints out a list, starting at the specified indentation,
to the specified print writer.
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by
getComponentAt(int, int) .
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by
getMinimumSize() .
| |||||||||||
Paints the container.
| |||||||||||
Paints each of the components in this container.
| |||||||||||
This method is deprecated.
As of JDK version 1.1,
replaced by
getPreferredSize() .
| |||||||||||
Prints the container.
| |||||||||||
Prints each of the components in this container.
| |||||||||||
Removes the specified component from this container.
| |||||||||||
Removes the component, specified by
index ,
from this container. | |||||||||||
Removes all the components from this container.
| |||||||||||
Removes the specified container listener so it no longer receives
container events from this container.
| |||||||||||
Makes this Container undisplayable by removing its connection
to its native screen resource.
| |||||||||||
Moves the specified component to the specified z-order index in
the container.
| |||||||||||
Sets whether this Container is the root of a focus traversal cycle.
| |||||||||||
Sets the focus traversal keys for a given traversal operation for this
Container.
| |||||||||||
Sets the focus traversal policy that will manage keyboard traversal of
this Container's children, if this Container is a focus cycle root.
| |||||||||||
Sets whether this container will be used to provide focus
traversal policy.
| |||||||||||
Sets the font of this container.
| |||||||||||
Sets the layout manager for this container.
| |||||||||||
Transfers the focus down one focus traversal cycle.
| |||||||||||
Updates the container.
| |||||||||||
Validates this container and all of its subcomponents.
|
Protected Methods | |||||||||||
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Adds the specified component to this container at the specified
index.
| |||||||||||
Returns a string representing the state of this
Container . | |||||||||||
Processes container events occurring on this container by
dispatching them to any registered ContainerListener objects.
| |||||||||||
Processes events on this container.
| |||||||||||
Recursively descends the container tree and recomputes the
layout for any subtrees marked as needing it (those marked as
invalid).
|
[Expand]
Inherited Methods | |||||||||||
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From class
java.awt.Component
| |||||||||||
From class
java.lang.Object
| |||||||||||
From interface
java.awt.MenuContainer
| |||||||||||
From interface
java.awt.image.ImageObserver
|
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).
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(Component, 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.
comp | the component to be added |
---|---|
constraints | an object expressing layout contraints for this component |
NullPointerException | if comp is null |
---|
Adds the specified component to this container.
This is a convenience method for addImpl(Component, Object, int)
.
This method is obsolete as of 1.1. Please use the
method add(Component, Object)
instead.
NullPointerException | if comp is null |
---|
Adds the specified component to this container at the given
position.
This is a convenience method for addImpl(Component, 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.
comp | the component to be added |
---|---|
index | the position at which to insert the component,
or -1 to append the component to the end |
comp
NullPointerException | if comp is null |
---|---|
IllegalArgumentException | if index is invalid (see
addImpl(Component, Object, int) for details) |
Appends the specified component to the end of this container.
This is a convenience method for addImpl(Component, 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.
comp | the component to be added |
---|
NullPointerException | if comp is null |
---|
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(Component, 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.
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 |
NullPointerException | if comp is null |
---|---|
IllegalArgumentException | if index is invalid (see
addImpl(Component, Object, int) for details) |
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.
Refer to AWT Threading Issues for details on AWT's threading model.
l | the container listener |
---|
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.
Adds a PropertyChangeListener to the listener list for a specific property. The specified property may be user-defined, or one of the following defaults:
If listener is null, no exception is thrown and no action is performed.
propertyName | one of the property names listed above |
---|---|
listener | the PropertyChangeListener to be added |
Adds a PropertyChangeListener to the listener list. The listener is registered for all bound properties of this class, including the following:
If listener is null, no exception is thrown and no action is performed.
listener | the PropertyChangeListener to be added |
---|
Sets the ComponentOrientation
property of this container
and all components contained within it.
o | the new component orientation of this container and the components contained within it. |
---|
NullPointerException | if orientation is null. |
---|
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.
id | one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS |
---|
true
if the 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_KEYS |
---|
This method is deprecated.
As of JDK version 1.1,
replaced by getComponentCount().
This method is deprecated.
As of JDK version 1.1,
replaced by dispatchEvent(AWTEvent e)
Causes this container to lay out its components. Most programs
should not call this method directly, but should invoke
the validate
method instead.
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.
p | the point. |
---|
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.
x | the x coordinate |
---|---|
y | the y coordinate |
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.
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.
Gets the nth component in this container.
n | the index of the component to get. |
---|
ArrayIndexOutOfBoundsException | if the nth value does not exist. |
---|
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).
x | the x coordinate |
---|---|
y | the y coordinate |
Gets the component that contains the specified point.
p | the point. |
---|
null
if the component does
not contain the point.Gets the number of components in this panel.
Returns the z-order index of the component inside the container. The higher a component is in the z-order hierarchy, the lower its index. The component with the lowest z-order index is painted last, above all other child components.
comp | the component being queried |
---|
null
or doesn't belong to the containerGets all the components in this container.
Returns an array of all the container listeners registered on this container.
ContainerListener
s
or an empty array if no container
listeners are currently registeredReturns 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.
id | one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS |
---|
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 |
---|
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.
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 an array of all the objects currently registered
as 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.
listenerType | 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 |
---|
Returns the maximum size of this container. If the maximum size has
not been set explicitly by setMaximumSize(Dimension)
and the LayoutManager
installed on this Container
is an instance of LayoutManager2
, then
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.
Dimension
that represents
the maximum size of this container.Returns the minimum size of this container. If the minimum size has
not been set explicitly by setMinimumSize(Dimension)
and this Container
has a non-null
LayoutManager
,
then 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.
Dimension
that represents
the minimum size of this container.Returns the position of the mouse pointer in this Container
's
coordinate space if the Container
is under the mouse pointer,
otherwise returns null
.
This method is similar to 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 account |
---|
Component
, or nullHeadlessException | if GraphicsEnvironment.isHeadless() returns true |
---|
Returns the preferred size of this container. If the preferred size has
not been set explicitly by setPreferredSize(Dimension)
and this Container
has a non-null
LayoutManager
,
then 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.
Dimension
that represents
the preferred size of this container.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.
If the LayoutManager
installed on this container is
an instance of LayoutManager2
, then
invalidateLayout(Container)
is invoked on
it supplying this Container
as the argument.
Checks if the component is contained in the component hierarchy of this container.
c | the component |
---|
true
if it is an ancestor;
false
otherwise.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.
container | the Container to be tested |
---|
true
if the specified Container is a focus-cycle-
root of this Container; false
otherwiseReturns 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 provides focus traversal
policy. If this property is set to 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
otherwiseReturns 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.
true
if the focus traversal policy has been
explicitly set for this Container; false
otherwise.
This method is deprecated.
As of JDK version 1.1,
replaced by doLayout()
.
Prints a listing of this container to the specified output stream. The listing starts at the specified indentation.
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.
out | a print stream |
---|---|
indent | the number of spaces to indent |
Prints out a list, starting at the specified indentation, to the specified print writer.
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.
out | a print writer |
---|---|
indent | the number of spaces to indent |
This method is deprecated.
As of JDK version 1.1,
replaced by getComponentAt(int, int)
.
This method is deprecated.
As of JDK version 1.1,
replaced by getMinimumSize()
.
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.
g | the specified Graphics window |
---|
Paints each of the components in this container.
g | the graphics context. |
---|
This method is deprecated.
As of JDK version 1.1,
replaced by getPreferredSize()
.
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.
g | the specified Graphics window |
---|
Prints each of the components in this container.
g | the graphics context. |
---|
Removes the specified component from this container.
This method also notifies the layout manager to remove the
component from this container's layout via the
removeLayoutComponent
method.
Note: If a component has been removed from a container that
had been displayed, validate()
must be
called on that container to reflect changes.
If multiple components are being removed, you can improve
efficiency by calling validate()
only once,
after all the components have been removed.
comp | the component to be removed |
---|
Removes the component, specified by index
,
from this container.
This method also notifies the layout manager to remove the
component from this container's layout via the
removeLayoutComponent
method.
Note: If a component has been removed from a container that
had been displayed, validate()
must be
called on that container to reflect changes.
If multiple components are being removed, you can improve
efficiency by calling validate()
only once,
after all the components have been removed.
index | the index of the component to be removed |
---|
ArrayIndexOutOfBoundsException | if index is not in
range [0, getComponentCount()-1] |
---|
Removes all the components from this container.
This method also notifies the layout manager to remove the
components from this container's layout via the
removeLayoutComponent
method.
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.
Refer to AWT Threading Issues for details on AWT's threading model.
l | the container listener |
---|
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.
Moves the specified component to the specified z-order index in the container. The z-order determines the order that components are painted; the component with the highest z-order paints first and the component with the lowest z-order paints last. Where components overlap, the component with the lower z-order paints over the component with the higher z-order.
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.
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 moved |
---|---|
index | the position in the container's list to
insert the component, where getComponentCount()
appends to the end |
NullPointerException | if comp is
null |
---|---|
IllegalArgumentException | if comp is one of the
container's parents |
IllegalArgumentException | 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 container |
IllegalArgumentException | if adding a container to itself |
IllegalArgumentException | if adding a Window
to a container |
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.
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 cycle |
---|
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 |
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.
id | one of KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS, or KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS |
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keystrokes | the Set of AWTKeyStroke for the specified operation |
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 |
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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.
policy | the new focus traversal policy for this Container |
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Sets whether this container will be used to provide focus
traversal policy. Container with this property as
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 policy |
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Sets the font of this container.
f | The font to become this container's font. |
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Sets the layout manager for this container.
mgr | the specified layout manager |
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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.
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.
g | the specified Graphics window |
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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.
If this Container
is not valid, this method invokes
the validateTree
method and marks this Container
as valid. Otherwise, no action is performed.
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
.
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
addLayoutComponent(Component, Object)
is invoked on
it. If the current layout manager does not implement
LayoutManager2
, and constraints is a String
, then
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)
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 |
IllegalArgumentException | 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()] |
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IllegalArgumentException | if comp is an ancestor of
this container |
IllegalArgumentException | if adding a window to a container |
NullPointerException | if comp is null |
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
.
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:
addContainerListener
enableEvents
Note that if the event parameter is null
the behavior is unspecified and may result in an
exception.
e | the container event |
---|
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.
e | the event |
---|
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
.