Java by API/javax.swing.event/TreeSelectionEvent

TreeSelectionEvent: getNewLeadSelectionPath()

 
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.MutableTreeNode;
import javax.swing.tree.TreePath;
public class MainClass extends JPanel {
  public static void main(String[] args) {
    // create a hierarchy of nodes
    MutableTreeNode root = new DefaultMutableTreeNode("A");
    MutableTreeNode bNode = new DefaultMutableTreeNode("B");
    MutableTreeNode cNode = new DefaultMutableTreeNode("C");
    root.insert(bNode, 0);
    root.insert(cNode, 1);
    bNode.insert(new DefaultMutableTreeNode("1"), 0);
    bNode.insert(new DefaultMutableTreeNode("2"), 1);
    cNode.insert(new DefaultMutableTreeNode("1"), 0);
    cNode.insert(new DefaultMutableTreeNode("2"), 1);
    final DefaultTreeModel model = new DefaultTreeModel(root);
    final JTree tree = new JTree(model);
    final JTextField nameField = new JTextField("Z");
    final JButton button = new JButton("Add");
    button.setEnabled(false);
    button.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        TreePath tp = tree.getSelectionPath();
        MutableTreeNode insertNode = (MutableTreeNode) tp.getLastPathComponent();
        int insertIndex = 0;
        if (insertNode.getParent() != null) {
          MutableTreeNode parent = (MutableTreeNode) insertNode.getParent();
          insertIndex = parent.getIndex(insertNode) + 1;
          insertNode = parent;
        }
        MutableTreeNode node = new DefaultMutableTreeNode(nameField.getText());
        model.insertNodeInto(node, insertNode, insertIndex);
      }
    });
    JPanel addPanel = new JPanel(new GridLayout(2, 1));
    addPanel.add(nameField);
    addPanel.add(button);
    tree.addTreeSelectionListener(new TreeSelectionListener() {
      public void valueChanged(TreeSelectionEvent e) {
        TreePath tp = e.getNewLeadSelectionPath();
        button.setEnabled(tp != null);
      }
    });
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 200);
    frame.getContentPane().add(new JScrollPane(tree));
    frame.getContentPane().add(addPanel, BorderLayout.SOUTH);
    frame.setVisible(true);
  }
}

TreeSelectionEvent: isAddedPath(int index)

  
import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.TreePath;
public class Main {
  public static void main(String[] argv) throws Exception {
    JTree tree = new JTree();
    tree.addTreeSelectionListener(new TreeSelectionListener() {
      public void valueChanged(TreeSelectionEvent evt) {
        TreePath[] paths = evt.getPaths();
        for (int i = 0; i < paths.length; i++) {
          if (evt.isAddedPath(i)) {
            System.out.println("This node has been selected");
          } else {
            System.out.println("This node has been deselected"); 
          }
        }
      }
    });
  }
}