java展开或者合并JTree，java展开合并JTree,Javaimport j

java展开或者合并JTree，java展开合并JTree,Javaimport j

Java

import javax.swing.*;import javax.swing.tree.*;import java.awt.event.*;import java.awt.*;import java.util.*;public class SimpleTree extends JPanel {  JTree tree;  DefaultMutableTreeNode root, node1, node2, node3, node4;  public SimpleTree() {    root = new DefaultMutableTreeNode("root", true);    node1 = new DefaultMutableTreeNode("node 1", true);    node2 = new DefaultMutableTreeNode("node 2" , true);    node3 = new DefaultMutableTreeNode("node 3" , true);    node4 = new DefaultMutableTreeNode("node 4" , true);    root.add(node1);    node1.add(node2);    root.add(node3);    node3.add(node4);    setLayout(new BorderLayout());    tree = new JTree(root);    add(new JScrollPane((JTree)tree),"Center");    }  public Dimension getPreferredSize(){    return new Dimension(200, 120);    }  public static void main(String s[]){    MyJFrame frame = new MyJFrame("Tree Collapse Expand");    }  }class WindowCloser extends WindowAdapter {  public void windowClosing(WindowEvent e) {    Window win = e.getWindow();    win.setVisible(false);    System.exit(0);    }  }class MyJFrame extends JFrame implements ActionListener {  JButton b1, b2, b3;  SimpleTree panel;  MyJFrame(String s) {    super(s);    setForeground(Color.black);    setBackground(Color.lightGray);    panel = new SimpleTree();    expandAll(panel.tree);    getContentPane().add(panel,"Center");    b1 = new JButton("Expand");    b3 = new JButton("Expand to last");    b2 = new JButton("Collapse");    b1.addActionListener(this);    b2.addActionListener(this);    b3.addActionListener(this);    getContentPane().add(b1,"West");    getContentPane().add(b3,"North");    getContentPane().add(b2,"East");    setSize(300,300);    setVisible(true);    setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);    addWindowListener(new WindowCloser());    }  public void actionPerformed(ActionEvent ae) {    if (ae.getSource() == b1) expandAll(panel.tree);    if (ae.getSource() == b3) expandToLast(panel.tree);    if (ae.getSource() == b2) collapseAll(panel.tree);    }  public void expandAll(JTree tree) {    int row = 0;    while (row < tree.getRowCount()) {      tree.expandRow(row);      row++;      }    }  public void expandToLast(JTree tree) {    // expand to the last leaf from the root    DefaultMutableTreeNode  root;    root = (DefaultMutableTreeNode) tree.getModel().getRoot();    tree.scrollPathToVisible(new TreePath(root.getLastLeaf().getPath()));    }  /*  // alternate version, suggested by C.Kaufhold  public void expandToLast(JTree tree) {    TreeModel data = tree.getModel();    Object node = data.getRoot();    if (node == null) return;    TreePath p = new TreePath(node);    while (true) {         int count = data.getChildCount(node);         if (count == 0) break;         node = data.getChild(node, count - 1);         p = p.pathByAddingChild(node);    }    tree.scrollPathToVisible(p);  }  */  public void collapseAll(JTree tree) {    int row = tree.getRowCount() - 1;    while (row >= 0) {      tree.collapseRow(row);      row--;      }    } }