Listening for Expansion and Collapse Events in a JTree Component : Tree « Swing JFC « Java

1. Java
2. Swing JFC
3. Tree

Listening for Expansion and Collapse Events in a JTree Component

    

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.event.TreeWillExpandListener;
import javax.swing.tree.ExpandVetoException;
import javax.swing.tree.TreePath;

public class Main {
  public static void main() {
    JTree tree = new JTree();
    tree.addTreeWillExpandListener(new MyTreeWillExpandListener());
    tree.addTreeExpansionListener(new MyTreeExpansionListener());

    JFrame f = new JFrame();
    f.add(new JScrollPane(tree));
    f.setSize(300, 300);
    f.setVisible(true);

  }
}

class MyTreeWillExpandListener implements TreeWillExpandListener {
  public void treeWillExpand(TreeExpansionEvent evt) throws ExpandVetoException {
    JTree tree = (JTree) evt.getSource();

    TreePath path = evt.getPath();
    boolean veto = false;
    if (veto) {
      throw new ExpandVetoException(evt);
    }
  }

  public void treeWillCollapse(TreeExpansionEvent evt) throws ExpandVetoException {
    JTree tree = (JTree) evt.getSource();

    TreePath path = evt.getPath();
    boolean veto = false;
    if (veto) {
      throw new ExpandVetoException(evt);
    }
  }
}

class MyTreeExpansionListener implements TreeExpansionListener {
  public void treeExpanded(TreeExpansionEvent evt) {
    JTree tree = (JTree) evt.getSource();

    TreePath path = evt.getPath();
    System.out.println("treeExpanded");
  }

  public void treeCollapsed(TreeExpansionEvent evt) {
    JTree tree = (JTree) evt.getSource();

    TreePath path = evt.getPath();
    System.out.println("treeCollapsed");
  }
}

   
    
    
    
  

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