JTree model.nodechanged(节点)丢失数据

Question

我正在用 JTree 测试一些代码，我注意到 model.reload() 给出的输出与 model.nodeChanged(currentNode) 不同。正确的输出是从 model.reload() 获得的。这是同一代码的两个输出：

我的代码如下：

public class test {

    private JFrame frame;
    JTree tree;
    DefaultMutableTreeNode root;
    DefaultTreeModel model;
    private Map<String, DefaultMutableTreeNode> treeMap;

    public static void main(String[] args) {
        test t = new test();
        try {
            Thread.sleep(1000 * 5);
        } catch (Exception e) {

        }
        t.add_new_folder("Data", "trial 0");
        t.add_new_folder("Data/trial 0", "trial 1");
        t.add_new_folder("Data/trial 0/trial 1", "trial 2");
        t.add_new_folder("Data", "trial 1");

        try {
            Thread.sleep(1000 * 5);
        } catch (Exception e) {

        }
        t.add_new_folder("Data/trial 1", "trial 2");
        t.add_new_folder("Data", "trial 2");
    }

    public test() {
        frame = new JFrame("using reload");
        tree = new JTree();
        root = new DefaultMutableTreeNode("Data");
        model = new DefaultTreeModel(root);
        tree.setModel(model);
        frame.getContentPane().add(tree, BorderLayout.WEST);
        frame.setVisible(true);
        frame.setSize(500, 500);
        treeMap = new HashMap<>();
        treeMap.put("Data", root);
    }

    public void add_new_folder(String path, String name) {
        DefaultMutableTreeNode currentNode = treeMap.get(path);
        DefaultMutableTreeNode childNode = new DefaultMutableTreeNode(name);
        currentNode.add(childNode);
        treeMap.put(path + "/" + name, childNode);
        model.reload();
        //model.nodeChanged(currentNode);
    }
}

我还需要使用 model.nodeChanged()，因为它与 model.reload 不同，它使扩展路径保持不变。任何解释和如何解决？

Answer 1

Any idea why this problem facing me with the Tree?

如下图，当正确synchronized, the results are the same. As shown , you can control visibility using expandRow() and scrollPathToVisible(). Using Thread.sleep() will simply block the thread on which it is called. Because Swing is single-threaded, the results are unpredictable. Instead use java.swing.Timer or SwingWorker需要时。

Try to put some sleep between adding nodes and expand any path and in the continue code the problem will appear as stated in my question.

由于 mentioned 的原因，使用 Thread.sleep() 的结果不可靠。使用 java.swing.Timer 揭示了问题： nodeChanged() 反映了对节点本身的更改。因为您已经更改了节点的子节点，所以改为调用 nodeStructureChanged()。

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JFrame;
import javax.swing.JTree;
import javax.swing.Timer;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;

public class Test {

    private final JFrame frame;
    private final JTree tree;
    private final DefaultMutableTreeNode root;
    private final DefaultTreeModel model;
    private final Map<String, DefaultMutableTreeNode> treeMap;
    private final boolean reload;
    private int index;
    private final String[] folders = {
        "Data", "trial 0",
        "Data/trial 0", "trial 1",
        "Data/trial 0/trial 1", "trial 2",
        "Data", "trial 1",
        "Data/trial 1", "trial 2",
        "Data", "trial 2"
    };

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            new Test(true);
            new Test(false);
        });
    }

    public Test(boolean reload) {
        this.reload = reload;
        frame = new JFrame(String.valueOf(reload));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        treeMap = new HashMap<>();
        root = new DefaultMutableTreeNode("Data");
        model = new DefaultTreeModel(root);
        tree = new JTree(model);
        treeMap.put("Data", root);
        frame.add(tree, BorderLayout.WEST);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        Timer t = new Timer(100, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (index < folders.length) {
                    addNewFolder(folders[index++], folders[index++]);
                    for (int i = 0; i < tree.getRowCount(); i++) {
                        tree.expandRow(i);
                    }
                    frame.pack();
                }
            }
        });
        t.start();
    }

    private void addNewFolder(String path, String name) {
        DefaultMutableTreeNode currentNode = treeMap.get(path);
        DefaultMutableTreeNode childNode = new DefaultMutableTreeNode(name);
        currentNode.add(childNode);
        treeMap.put(path + "/" + name, childNode);
        if (reload) {
            model.reload();
        } else {
            model.nodeStructureChanged(currentNode);
        }
    }
}

JTree model.nodechanged(节点)丢失数据

JTree model.nodechanged(Node) loses data

java

eclipse

swing

jtree