jtree,隐藏根后添加第一层枝不显示。



import java.awt.BorderLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;



import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JScrollPane;

import javax.swing.JTree;

import javax.swing.tree.DefaultMutableTreeNode;

import javax.swing.tree.DefaultTreeModel;



public class JtreeTest extends JFrame

{

	private static int i = 1;



	private DefaultMutableTreeNode root;

	private DefaultTreeModel treeModel;

	private JTree tree;



	public JtreeTest()

	{

		root = new DefaultMutableTreeNode("默认根");



		// 利用根节点创建TreeModel

		this.treeModel = new DefaultTreeModel(root);



		tree = new JTree(treeModel);

//		 tree.setRootVisible(false); // 设置树的系统根不可见



		DefaultMutableTreeNode node0 = new DefaultMutableTreeNode("文件0");

		treeModel.insertNodeInto(node0, root, root.getChildCount());

		tree.expandRow(0);



		JScrollPane treeScrollPane = new JScrollPane(tree);

		this.getContentPane().add(treeScrollPane, BorderLayout.SOUTH);



		JButton btn = new JButton("增加树枝");

		btn.addActionListener(new ActionListener()

		{

			@Override

			public void actionPerformed(ActionEvent e)

			{

				String temp = "文件" + i++;

				DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(temp);



				JtreeTest.this.treeModel.insertNodeInto(node1, root, root.getChildCount());



				JtreeTest.this.tree.updateUI();

				

				System.out.println(temp);

			}

		});

		this.getContentPane().add(btn, BorderLayout.NORTH);



		this.setTitle("树形菜单");

		this.pack();

		this.setVisible(true);

		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	}



	public static void main(String[] args)

	{

		new JtreeTest();

	}

}

未隐藏根如上图，按按钮可以添加枝

但是隐藏根后，默认的文件0都不显示了，按钮后界面没变化，但是输出能看到事件还是执行了

Jtree listener Java SE --------------------编程问答--------------------



import java.awt.BorderLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;



import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JScrollPane;

import javax.swing.JTree;

import javax.swing.tree.DefaultMutableTreeNode;

import javax.swing.tree.DefaultTreeModel;



public class JtreeTest extends JFrame {

	private static int i = 1;



	private DefaultMutableTreeNode root;

	private DefaultTreeModel treeModel;

	private JTree tree;



	public JtreeTest() {

		root = new DefaultMutableTreeNode("默认根");



		// 利用根节点创建TreeModel

		this.treeModel = new DefaultTreeModel(root);



		tree = new JTree(treeModel);

		tree.setRootVisible(false); // 设置树的系统根不可见



		DefaultMutableTreeNode node0 = new DefaultMutableTreeNode("文件0");

		treeModel.insertNodeInto(node0, root, root.getChildCount());

		tree.expandRow(0);



		JScrollPane treeScrollPane = new JScrollPane(tree);

		this.getContentPane().add(treeScrollPane, BorderLayout.SOUTH);



		JButton btn = new JButton("增加树枝");

		btn.addActionListener(new ActionListener() {

			@Override

			public void actionPerformed(ActionEvent e) {

				String temp = "文件" + i++;

				DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(temp);



				JtreeTest.this.treeModel.insertNodeInto(node1, root, root.getChildCount());



				JtreeTest.this.tree.updateUI();



				System.out.println(temp);

			}

		});

		this.getContentPane().add(btn, BorderLayout.NORTH);



		this.setTitle("树形菜单");

		this.pack();

		this.setVisible(true);

		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	}



	public static void main(String[] args) {

		new JtreeTest();

	}

}

测试没问题：

--------------------编程问答--------------------

引用 1 楼 huxiweng 的回复:



import java.awt.BorderLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;



import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JScrollPane;

import javax.swing.JTree;

import javax.swing.tree.DefaultMutableTreeNode;

import javax.swing.tree.DefaultTreeModel;



public class JtreeTest extends JFrame {

	private static int i = 1;



	private DefaultMutableTreeNode root;

	private DefaultTreeModel treeModel;

	private JTree tree;



	public JtreeTest() {

		root = new DefaultMutableTreeNode("默认根");



		// 利用根节点创建TreeModel

		this.treeModel = new DefaultTreeModel(root);



		tree = new JTree(treeModel);

		tree.setRootVisible(false); // 设置树的系统根不可见



		DefaultMutableTreeNode node0 = new DefaultMutableTreeNode("文件0");

		treeModel.insertNodeInto(node0, root, root.getChildCount());

		tree.expandRow(0);



		JScrollPane treeScrollPane = new JScrollPane(tree);

		this.getContentPane().add(treeScrollPane, BorderLayout.SOUTH);



		JButton btn = new JButton("增加树枝");

		btn.addActionListener(new ActionListener() {

			@Override

			public void actionPerformed(ActionEvent e) {

				String temp = "文件" + i++;

				DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(temp);



				JtreeTest.this.treeModel.insertNodeInto(node1, root, root.getChildCount());



				JtreeTest.this.tree.updateUI();



				System.out.println(temp);

			}

		});

		this.getContentPane().add(btn, BorderLayout.NORTH);



		this.setTitle("树形菜单");

		this.pack();

		this.setVisible(true);

		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	}



	public static void main(String[] args) {

		new JtreeTest();

	}

}

测试没问题：

版主，我又去运行到看了，还是出不来，请问下可能会是什么原因引起的呢？

JDK1.7.0.25 会不会是这个引起的？

补充：Java ,  Java SE