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.
If client code has explicitly set the focusability of a Component by either
overriding Component.isFocusTraversable() or
Component.isFocusable() , or by calling
Component.setFocusable() , then a DefaultFocusTraversalPolicy
behaves exactly like a ContainerOrderFocusTraversalPolicy. If, however, the
Component is relying on default focusability, then a
DefaultFocusTraversalPolicy will reject all Components with non-focusable
peers. This is the default FocusTraversalPolicy for all AWT Containers.
The focusability of a peer is implementation-dependent. Sun recommends that
all implementations for a particular native platform construct peers with
the same focusability. The recommendations for Windows and Unix are that
Canvases, Labels, Panels, Scrollbars, ScrollPanes, Windows, and lightweight
Components have non-focusable peers, and all other Components have focusable
peers. These recommendations are used in the Sun AWT implementations. Note
that the focusability of a Component's peer is different from, and does not
impact, the focusability of the Component itself.
Please see
How to Use the Focus Subsystem,
a section in The Java Tutorial, and the
Focus Specification
for more information. |