限制除了第一级子级以外的JTree节点的添加 [英] Restricting the addition of nodes of a JTree except for the 1st level child

问题描述

我一直在尝试很多方法来限制将代码仅添加到第1级的代码.这意味着用户只能将节点添加到JTree的1级子级.

I have been trying a lot of approaches on how to limit my code on adding nodes only to the 1st level. This means that the user can only add nodes to the 1st level children of a JTree.

可以通过2种方法在程序中添加节点 1.添加节点按钮 2.选择>右键单击>添加节点(在这里，如果选择了非第一级子级，我想禁用此行为.虽然它是一个长镜头)

Adding a node in my program can be done in 2 ways 1. Add node button 2. Select > Right click > Add node (In here, I wanted to disable this behavior if it a non 1st level child is selected. It's a long shot though )

我需要一个允许添加其他级别节点的验证.谢谢！

I need a validation that permits the addition of nodes in other levels. Thanks!

这是工作代码:

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.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeNode;
import javax.swing.tree.TreePath;

public class ProblemTree extends JFrame {

    private DefaultMutableTreeNode root = new DefaultMutableTreeNode("Root");
    private DefaultTreeModel model = new DefaultTreeModel(root);
    private JTree tree = new JTree(model);
    private JButton addButton = new JButton("Add Node to 1st level only");

    public ProblemTree() {
        DefaultMutableTreeNode n1 = new DefaultMutableTreeNode(
                "1st level: Child 1");
        n1.add(new DefaultMutableTreeNode("2nd level: Child l"));
        DefaultMutableTreeNode n2 = new DefaultMutableTreeNode(
                "1st level: Child 2");
        n2.add(new DefaultMutableTreeNode("2nd level: Child 2"));
        DefaultMutableTreeNode n3 = new DefaultMutableTreeNode(
                "1st level: Child 3");
        n3.add(new DefaultMutableTreeNode("2nd level: Child 3"));

        root.add(n1);
        root.add(n2);
        root.add(n3);

        tree.setEditable(true);
        tree.setSelectionRow(0);
        tree.setRootVisible(true);
        tree.setShowsRootHandles(true);

        final JPopupMenu popupMenu = new JPopupMenu();
        JMenuItem runTask = new JMenuItem("New Node for 1st level only =( ");
        runTask.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                DefaultMutableTreeNode selNode = (DefaultMutableTreeNode) tree
                        .getLastSelectedPathComponent();
                if (selNode == null) {
                    return;
                }
                DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(
                        "New Node");
                model.insertNodeInto(newNode, selNode, selNode.getChildCount());

                TreeNode[] nodes = model.getPathToRoot(newNode);
                TreePath path = new TreePath(nodes);
                tree.scrollPathToVisible(path);
                tree.setSelectionPath(path);
                tree.startEditingAtPath(path);
            }
        });
        popupMenu.add(runTask);
        tree.setComponentPopupMenu(popupMenu);

        JScrollPane scrollPane = new JScrollPane(tree);
        getContentPane().add(scrollPane, BorderLayout.CENTER);

        JPanel panel = new JPanel();

        addButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                DefaultMutableTreeNode selNode = (DefaultMutableTreeNode) tree
                        .getLastSelectedPathComponent();
                if (selNode == null) {
                    return;
                }
                DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(
                        "New Node");
                model.insertNodeInto(newNode, selNode, selNode.getChildCount());

                TreeNode[] nodes = model.getPathToRoot(newNode);
                TreePath path = new TreePath(nodes);
                tree.scrollPathToVisible(path);
                tree.setSelectionPath(path);
                tree.startEditingAtPath(path);
            }
        });
        panel.add(addButton);

        getContentPane().add(panel, BorderLayout.SOUTH);
        setSize(700, 400);
        setVisible(true);
    }

    public static void main(String[] arg) {
        ProblemTree pt = new ProblemTree();
    }
}

推荐答案

只需替换

tree.setComponentPopupMenu(popupMenu); 

具有:

tree.addMouseListener(new MouseAdapter() {
    @Override
        public void mousePressed(MouseEvent e) {
        if (SwingUtilities.isRightMouseButton(e)) {
            int row = tree.getClosestRowForLocation(e.getX(), e.getY());
            tree.setSelectionRow(row);
            if (tree.getSelectionPath().getPathCount() == 2) {
                popupMenu.show(e.getComponent(), e.getX(), e.getY());
            }
        }
    }
});

并控制您的按钮添加:

addButton.setEnabled(false);
tree.addTreeSelectionListener(new TreeSelectionListener() {
    @Override
    public void valueChanged(TreeSelectionEvent e) {
        addButton.setEnabled((tree.getSelectionPath().getPathCount() == 2));
    }
});

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