java.awt.ContainerOrderFocusTraversalPolicy Maven / Gradle / Ivy
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*/
package java.awt;
/**
* A FocusTraversalPolicy that determines traversal order based on the order
* of child Components in a Container. From a particular focus cycle root, the
* policy makes a pre-order traversal of the Component hierarchy, and traverses
* a Container's children according to the ordering of the array returned by
* Container.getComponents(). Portions of the hierarchy that are
* not visible and displayable will not be searched.
*
* By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus
* down-cycle. That is, during normal forward 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.
*
* By default, methods of this class with return a Component only if it is
* visible, displayable, enabled, and focusable. Subclasses can modify this
* behavior by overriding the accept method.
*
* @author David Mendenhall
* @version 1.3, 01/23/03
*
* @see Container#getComponents
* @since 1.4
*/
public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
implements java.io.Serializable
{
/*
* JDK 1.4 serialVersionUID
*/
private static final long serialVersionUID = 486933713763926351L;
private boolean implicitDownCycleTraversal;
public ContainerOrderFocusTraversalPolicy() { }
/**
* Returns the Component that should receive the focus after aComponent.
* focusCycleRoot must be a focus cycle root of aComponent.
*
* By default, ContainerOrderFocusTraversalPolicy implicitly transfers
* focus down-cycle. That is, during normal forward 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.
*
* @param focusCycleRoot a focus cycle root of aComponent
* @param aComponent a (possibly indirect) child of focusCycleRoot, or
* focusCycleRoot itself
* @return the Component that should receive the focus after aComponent, or
* null if no suitable Component can be found
* @throws IllegalArgumentException if focusCycleRoot is not a focus cycle
* root of aComponent, or if either focusCycleRoot or aComponent is
* null
*/
public Component getComponentAfter(Container focusCycleRoot, Component
aComponent)
{ return null; }
/**
* Returns the Component that should receive the focus before aComponent.
* focusCycleRoot must be a focus cycle root of aComponent.
*
* @param focusCycleRoot a focus cycle root of aComponent
* @param aComponent a (possibly indirect) child of focusCycleRoot, or
* focusCycleRoot itself
* @return the Component that should receive the focus before aComponent,
* or null if no suitable Component can be found
* @throws IllegalArgumentException if focusCycleRoot is not a focus cycle
* root of aComponent, or if either focusCycleRoot or aComponent is
* null
*/
public Component getComponentBefore(Container focusCycleRoot, Component
aComponent)
{ return null; }
/**
* 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.
*
* @param focusCycleRoot the focus cycle root whose first Component is to
* be returned
* @return the first Component in the traversal cycle when focusCycleRoot
* is the focus cycle root, or null if no suitable Component can be
* found
* @throws IllegalArgumentException if focusCycleRoot is null
*/
public Component getFirstComponent(Container focusCycleRoot) { return null; }
/**
* 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.
*
* @param focusCycleRoot the focus cycle root whose last Component is to be
* returned
* @return the last Component in the traversal cycle when focusCycleRoot is
* the focus cycle root, or null if no suitable Component can be
* found
* @throws IllegalArgumentException if focusCycleRoot is null
*/
public Component getLastComponent(Container focusCycleRoot) { return null; }
/**
* Returns the default Component to focus. This Component will be the first
* to receive focus when traversing down into a new focus traversal cycle
* rooted at focusCycleRoot. The default implementation of this method
* returns the same Component as getFirstComponent.
*
* @param focusCycleRoot the focus cycle root whose default Component is to
* be returned
* @return the default Component in the traversal cycle when focusCycleRoot
* is the focus cycle root, or null if no suitable Component can be
* found
* @see #getFirstComponent
* @throws IllegalArgumentException if focusCycleRoot is null
*/
public Component getDefaultComponent(Container focusCycleRoot) {return null; }
/**
* Sets whether this ContainerOrderFocusTraversalPolicy transfers focus
* down-cycle implicitly. If true, during normal forward focus
* traversal, the Component traversed after a focus cycle root will be the
* focus-cycle-root's default Component to focus. If false,
* the next Component in the focus traversal cycle rooted at the specified
* focus cycle root will be traversed instead. The default value for this
* property is true.
*
* @param implicitDownCycleTraversal whether this
* ContainerOrderFocusTraversalPolicy transfers focus down-cycle
* implicitly
* @see #getImplicitDownCycleTraversal
* @see #getFirstComponent
*/
public void setImplicitDownCycleTraversal(boolean
implicitDownCycleTraversal)
{ }
/**
* Returns whether this ContainerOrderFocusTraversalPolicy transfers focus
* down-cycle implicitly. If true, during normal forward focus
* traversal, the Component traversed after a focus cycle root will be the
* focus-cycle-root's default Component to focus. If false,
* the next Component in the focus traversal cycle rooted at the specified
* focus cycle root will be traversed instead.
*
* @return whether this ContainerOrderFocusTraversalPolicy transfers focus
* down-cycle implicitly
* @see #setImplicitDownCycleTraversal
* @see #getFirstComponent
*/
public boolean getImplicitDownCycleTraversal() { return false; }
/**
* Determines whether a Component is an acceptable choice as the new
* focus owner. By default, this method will accept a Component if and
* only if it is visible, displayable, enabled, and focusable.
*
* @param aComponent the Component whose fitness as a focus owner is to
* be tested
* @return true if aComponent is visible, displayable,
* enabled, and focusable; false otherwise
*/
protected boolean accept(Component aComponent) { return false; }
}