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package javax.swing.event;

import java.util.EventListener;
import javax.swing.tree.ExpandVetoException;

The listener that's notified when a tree expands or collapses a node. For further information and examples see How to Write a Tree-Will-Expand Listener, a section in The Java Tutorial.
Author:Scott Violet
/** * The listener that's notified when a tree expands or collapses * a node. * For further information and examples see * <a href="https://docs.oracle.com/javase/tutorial/uiswing/events/treewillexpandlistener.html">How to Write a Tree-Will-Expand Listener</a>, * a section in <em>The Java Tutorial.</em> * * @author Scott Violet */
public interface TreeWillExpandListener extends EventListener {
Invoked whenever a node in the tree is about to be expanded.
Params:
  • event – a TreeExpansionEvent containing a TreePath object for the node
Throws:
/** * Invoked whenever a node in the tree is about to be expanded. * * @param event a {@code TreeExpansionEvent} containing a {@code TreePath} * object for the node * @throws ExpandVetoException to signify expansion has been canceled */
public void treeWillExpand(TreeExpansionEvent event) throws ExpandVetoException;
Invoked whenever a node in the tree is about to be collapsed.
Params:
  • event – a TreeExpansionEvent containing a TreePath object for the node
Throws:
/** * Invoked whenever a node in the tree is about to be collapsed. * * @param event a {@code TreeExpansionEvent} containing a {@code TreePath} * object for the node * @throws ExpandVetoException to signify collapse has been canceled */
public void treeWillCollapse(TreeExpansionEvent event) throws ExpandVetoException; }