java从CellEditorListener获取编辑的TreeNode

Question

早些时候，我问如何在树节点被重命名（here）时触发事件。我的问题得到了回答，但我遇到了另一个问题。我需要访问CellEditorListener的editingStopped事件中正在编辑的TreeNode。这是我必须执行的代码：

package com.gamecreator;

import javax.swing.event.CellEditorListener;
import javax.swing.event.ChangeEvent;
import javax.swing.tree.DefaultTreeCellEditor;

public class CustomCellEditorListener implements CellEditorListener {
    public CustomCellEditorListener() {

    }

    public void editingCanceled(ChangeEvent e) {

    }

    public void editingStopped(ChangeEvent e) {
        DefaultTreeCellEditor editor = (DefaultTreeCellEditor) e.getSource(); //This gives me the error.
        CustomTreeNode node = //What do I put here???;
        node.getResource().setName((String) node.getUserObject());

        //For debugging
        System.out.println(node.getResource().getName());
    }
}

我得到这个错误：

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: javax.swing.tree.DefaultTreeCellEditor$1 cannot be cast to javax.swing.tree.DefaultTreeCellEditor

编辑： 在另一次尝试中，我在CustomCellEditorListener中使用了此代码

public void editingStopped(ChangeEvent e) {
    TreePath path = ((CustomTreeCellEditor) e.getSource()).getLastPath();  //This gives me the error.
    CustomTreeNode node = (CustomTreeNode) path.getLastPathComponent();
    node.getResource().setName((String) node.getUserObject());

    //For debugging
    System.out.println(node.getResource().getName());
}

以及CustomTreeCeleditor中的此代码

public TreePath getLastPath() {
    return lastPath;
}

我也犯了同样的错误（我想我会的）。我所拥有的应该是有效的，所以剩下的唯一真正的问题是，“为什么我会出现错误，我怎样才能纠正它？”但是如果有人有更好的方法来完成这一点，我愿意倾听

编辑2： 我已经做了一个小例子，说明我正在努力实现的目标，可以在here中找到（这是一个Eclipse归档文件）

Answer 1

我找到了一个非常简单的解决方案。重命名TreeNode后，它将成为树中唯一选定的节点。因此，我能够使用：

    CustomTreeNode node = (CustomTreeNode) tree.getLastSelectedPathComponent();

Answer 2

似乎您想在DefaultMutableTreeNode中编辑Resource的名称。正如您所发现的，ChangeEvent发送到editingStopped()in而不是aDefaultTreeCellEditor的来源；它是编辑器的（匿名）UI委托

相反，在DefaultTreeCellEditor中重写getCellEditorValue()，如下所示。DefaultTreeCellRenderer只是通过^{}调用toString()，后者访问DefaultMutableTreeNode的用户对象

附录：注意isCellEditable()确保只有叶节点可以编辑

正如@kleopatra在评论中指出的那样，之前的TreeCellEditor实现是无效的，因为它修改了正在编辑的节点。下面的修订版本创建了一个具有更新名称的新节点；在这方面copy constructor将是有用的。优点是userObject仍然是Resource。另见本alternative approach

/**
 * @see https://stackoverflow.com/a/12651990/230513
 * @see https://stackoverflow.com/a/11639595/230513
 * @see https://stackoverflow.com/a/11113648/230513
 */
public class TreeEditDemo extends JPanel {

    private JTree tree;
    private DefaultMutableTreeNode root;
    private DefaultTreeCellEditor editor;
    private JLabel label = new JLabel(" ", JLabel.CENTER);

    public TreeEditDemo() {
        super(new BorderLayout());
        root = new DefaultMutableTreeNode("Nodes");
        root.add(new DefaultMutableTreeNode(new Resource("one")));
        root.add(new DefaultMutableTreeNode(new Resource("two")));
        root.add(new DefaultMutableTreeNode(new Resource("three")));
        final DefaultTreeModel treeModel = new DefaultTreeModel(root);
        tree = new JTree(treeModel);
        tree.setEditable(true);
        editor = new MyTreeCellEditor(tree,
            (DefaultTreeCellRenderer) tree.getCellRenderer());
        tree.setCellEditor(editor);
        tree.getInputMap().put(
            KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0), "startEditing");
        this.add(new JScrollPane(tree));
        this.add(label, BorderLayout.SOUTH);
        tree.addTreeSelectionListener(new TreeSelectionListener() {

            @Override
            public void valueChanged(TreeSelectionEvent e) {
                TreePath path = e.getNewLeadSelectionPath();
                if (path != null) {
                    DefaultMutableTreeNode node =
                        (DefaultMutableTreeNode) path.getLastPathComponent();
                    if (node.isLeaf()) {
                        Resource user = (Resource) node.getUserObject();
                        label.setText(user.toString());
                    } else {
                        label.setText(" ");
                    }
                }
            }
        });
        editor.addCellEditorListener(new CellEditorListener() {

            @Override
            public void editingStopped(ChangeEvent e) {
                label.setText(editor.getCellEditorValue().toString());
            }

            @Override
            public void editingCanceled(ChangeEvent e) {
            }
        });
    }

    private static class MyTreeCellEditor extends DefaultTreeCellEditor {

        public MyTreeCellEditor(JTree tree, DefaultTreeCellRenderer renderer) {
            super(tree, renderer);
        }

        @Override
        public Object getCellEditorValue() {
            String value = (String) super.getCellEditorValue();
            return new Resource(value);
        }

        @Override
        public boolean isCellEditable(EventObject e) {
            return super.isCellEditable(e)
                && ((TreeNode) lastPath.getLastPathComponent()).isLeaf();
        }
    }

    private static class Resource {

        String name;

        public Resource(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        @Override
        public String toString() {
            return getName();
        }
    }

    private void display() {
        JFrame f = new JFrame("TreeEditorDemo");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(this);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TreeEditDemo().display();
            }
        });
    }
}