从CellEditorListener获取编辑的TreeNode

  • Z时代
  • 2024-01-10
  • 分类：问答

之前我问过如何在重命名TreeNode时触发事件（此处）。我的问题已经回答，但是我遇到了另一个问题。我需要访问在CellEditorListener的editingStopped事件中正在编辑的TreeNode。这是我要做的代码：

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());
    }
}

我收到此错误：

线程“ AWT-EventQueue-0”中的异常java.lang.ClassCastException：javax.swing.tree.DefaultTreeCellEditor $ 1无法转换为javax.swing.tree.DefaultTreeCellEditor

编辑：在另一种尝试，我在CustomCellEditorListener中使用此代码

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());
}

和这段代码在CustomTreeCellEditor中

public TreePath getLastPath() {
    return lastPath;
}

我遇到了同样的错误（我希望会）。我应该做的工作是，所以唯一剩下的真正的问题是：“我为什么会收到错误以及如何解决该错误？”，但是，如果有人有更好的方法可以做到这一点，我愿意听。

编辑2：我已经做了什么，我试图完成，可以发现一个小例子在这里（这是一个Eclipse存档）

回答：

看来，要编辑的名字Resource在DefaultMutableTreeNode。正如您看到的，的源ChangeEvent发送到editingStopped()在没有一个DefaultTreeCellEditor; 它是编辑器的（匿名）UI委托。

而是getCellEditorValue()在您的中进行覆盖DefaultTreeCellEditor，如下所示。在DefaultTreeCellRenderer简单地调用toString()，通过convertValueToText()，它访问的用户对象DefaultMutableTreeNode。

附录：请注意，isCellEditable()确保只能编辑叶节点。

正如@kleopatra在注释中指出的那样，先前的TreeCellEditor实现无效，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；一个拷贝构造函数是在这方面非常有用。好处是userObject遗迹仍然是Resource。另请参见此替代方法。

/**
 * @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();
            }
        });
    }
}

以上是 从CellEditorListener获取编辑的TreeNode 的全部内容， 来源链接： utcz.com/qa/405592.html

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