Class LayoutFocusTraversalPolicy

java.lang.Object

java.awt.FocusTraversalPolicy

javax.swing.InternalFrameFocusTraversalPolicy

javax.swing.SortingFocusTraversalPolicy

javax.swing.LayoutFocusTraversalPolicy

All Implemented Interfaces:

Serializable

public class LayoutFocusTraversalPolicy
extends SortingFocusTraversalPolicy
implements Serializable

A SortingFocusTraversalPolicy which sorts Components based on their size, position, and orientation. Based on their size and position, Components are roughly categorized into rows and columns. For a Container with horizontal orientation, columns run left-to-right or right-to-left, and rows run top- to-bottom. For a Container with vertical orientation, columns run top-to- bottom and rows run left-to-right or right-to-left. See ComponentOrientation for more information. All columns in a row are fully traversed before proceeding to the next row.

Since:

1.4

See Also:

• ComponentOrientation

Constructor Summary

Constructors

Constructor	Description
LayoutFocusTraversalPolicy()	Constructs a LayoutFocusTraversalPolicy.

Method Summary

Modifier and Type	Method	Description
protected boolean	accept(Component aComponent)	Determines whether the specified Component is an acceptable choice as the new focus owner.
Component	getComponentAfter(Container aContainer, Component aComponent)	Returns the Component that should receive the focus after aComponent. aContainer must be a focus cycle root of aComponent.
Component	getComponentBefore(Container aContainer, Component aComponent)	Returns the Component that should receive the focus before aComponent. aContainer must be a focus cycle root of aComponent.
Component	getFirstComponent(Container aContainer)	Returns the first Component in the traversal cycle.
Component	getLastComponent(Container aContainer)	Returns the last Component in the traversal cycle.

Methods declared in class SortingFocusTraversalPolicy

getComparator, getDefaultComponent, getImplicitDownCycleTraversal, setComparator, setImplicitDownCycleTraversal

Modifier and Type	Method	Description
protected Comparator<? super Component>	getComparator()	Returns the Comparator which will be used to sort the Components in a focus traversal cycle.
Component	getDefaultComponent(Container aContainer)	Returns the default Component to focus.
boolean	getImplicitDownCycleTraversal()	Returns whether this SortingFocusTraversalPolicy transfers focus down- cycle implicitly.
protected void	setComparator(Comparator<? super Component> comparator)	Sets the Comparator which will be used to sort the Components in a focus traversal cycle.
void	setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal)	Sets whether this SortingFocusTraversalPolicy transfers focus down-cycle implicitly.

Methods declared in class InternalFrameFocusTraversalPolicy

getInitialComponent

Modifier and Type	Method	Description
Component	getInitialComponent(JInternalFrame frame)	Returns the Component that should receive the focus when a JInternalFrame is selected for the first time.

Methods declared in class FocusTraversalPolicy

getInitialComponent

Modifier and Type	Method	Description
Component	getInitialComponent(Window window)	Returns the Component that should receive the focus when a Window is made visible for the first time.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
String	toString()	Returns a string representation of the object.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

LayoutFocusTraversalPolicy

public LayoutFocusTraversalPolicy()

Constructs a LayoutFocusTraversalPolicy.

Method Details

getComponentAfter

public Component getComponentAfter(Container aContainer,
 Component aComponent)

Returns the Component that should receive the focus after aComponent. aContainer must be a focus cycle root of aComponent.

By default, LayoutFocusTraversalPolicy implicitly transfers focus down- cycle. That is, during normal focus traversal, the Component traversed after a focus cycle root will be the focus-cycle-root's default Component to focus. This behavior can be disabled using the setImplicitDownCycleTraversal method.

If aContainer is focus traversal policy provider, the focus is always transferred down-cycle.

Overrides:

getComponentAfter in class SortingFocusTraversalPolicy

Parameters:

aContainer - a focus cycle root of aComponent or a focus traversal policy provider

aComponent - a (possibly indirect) child of aContainer, or aContainer itself

Returns:

the Component that should receive the focus after aComponent, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if aContainer is not a focus cycle root of aComponent or a focus traversal policy provider, or if either aContainer or aComponent is null

getComponentBefore

public Component getComponentBefore(Container aContainer,
 Component aComponent)

Returns the Component that should receive the focus before aComponent. aContainer must be a focus cycle root of aComponent.

By default, LayoutFocusTraversalPolicy implicitly transfers focus down- cycle. That is, during normal focus traversal, the Component traversed after a focus cycle root will be the focus-cycle-root's default Component to focus. This behavior can be disabled using the setImplicitDownCycleTraversal method.

If aContainer is focus traversal policy provider, the focus is always transferred down-cycle.

Overrides:

getComponentBefore in class SortingFocusTraversalPolicy

Parameters:

aContainer - a focus cycle root of aComponent or a focus traversal policy provider

aComponent - a (possibly indirect) child of aContainer, or aContainer itself

Returns:

the Component that should receive the focus before aComponent, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if aContainer is not a focus cycle root of aComponent or a focus traversal policy provider, or if either aContainer or aComponent is null

getFirstComponent

public Component getFirstComponent(Container aContainer)

Returns the first Component in the traversal cycle. This method is used to determine the next Component to focus when traversal wraps in the forward direction.

Overrides:

getFirstComponent in class SortingFocusTraversalPolicy

Parameters:

aContainer - a focus cycle root of aComponent or a focus traversal policy provider whose first Component is to be returned

Returns:

the first Component in the traversal cycle of aContainer, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if aContainer is null

getLastComponent

public Component getLastComponent(Container aContainer)

Returns the last Component in the traversal cycle. This method is used to determine the next Component to focus when traversal wraps in the reverse direction.

Overrides:

getLastComponent in class SortingFocusTraversalPolicy

Parameters:

aContainer - a focus cycle root of aComponent or a focus traversal policy provider whose last Component is to be returned

Returns:

the last Component in the traversal cycle of aContainer, or null if no suitable Component can be found

Throws:

IllegalArgumentException - if aContainer is null

accept

protected boolean accept(Component aComponent)

Determines whether the specified Component is an acceptable choice as the new focus owner. This method performs the following sequence of operations:

1. Checks whether aComponent is visible, displayable, enabled, and focusable. If any of these properties is false, this method returns false.
2. If aComponent is an instance of JTable, returns true.
3. If aComponent is an instance of JComboBox, then returns the value of aComponent.getUI().isFocusTraversable(aComponent).
4. If aComponent is a JComponent with a JComponent.WHEN_FOCUSED InputMap that is neither null nor empty, returns true.
5. Returns the value of DefaultFocusTraversalPolicy.accept(aComponent).

Overrides:

accept in class SortingFocusTraversalPolicy

Parameters:

aComponent - the Component whose fitness as a focus owner is to be tested

Returns:

true if aComponent is a valid choice for a focus owner; otherwise false

See Also:

• Component.isVisible()
• Component.isDisplayable()
• Component.isEnabled()
• Component.isFocusable()
• ComboBoxUI.isFocusTraversable(JComboBox)
• JComponent.getInputMap(int)
• DefaultFocusTraversalPolicy.accept(Component)