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Java example source code file (bug6505523.java)

This example Java source code file (bug6505523.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

awt, defaultmutabletreenode, defaulttreemodel, event, exception, gui, jdk, jframe, jtree, npe, override, point, problem, rectangle, robot, runnable, suntoolkit, swing, tree

The bug6505523.java Java example source code

/*
 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 6505523
 * @summary NullPointerException in BasicTreeUI when a node is removed by expansion listener
 * @author Alexandr Scherbatiy
 * @run main bug6505523
 */
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.InputEvent;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeNode;
import sun.awt.SunToolkit;

public class bug6505523 {

    private static JTree tree;

    public static void main(String[] args) throws Exception {
        SunToolkit toolkit = (SunToolkit) Toolkit.getDefaultToolkit();
        Robot robot = new Robot();
        robot.setAutoDelay(50);

        SwingUtilities.invokeAndWait(new Runnable() {

            @Override
            public void run() {
                createAndShowGUI();
            }
        });

        toolkit.realSync();

        Point point = getRowPointToClick(2);
        robot.mouseMove(point.x, point.y);
        robot.mousePress(InputEvent.BUTTON1_MASK);
        robot.mouseRelease(InputEvent.BUTTON1_MASK);

        toolkit.realSync();

    }

    private static Point getRowPointToClick(final int row) throws Exception {

        final Point[] result = new Point[1];

        SwingUtilities.invokeAndWait(new Runnable() {

            @Override
            public void run() {
                Rectangle rect = tree.getRowBounds(row);
                Point point = new Point(rect.x - 5, rect.y + rect.height / 2);
                SwingUtilities.convertPointToScreen(point, tree);
                result[0] = point;
            }
        });

        return result[0];
    }

    private static void createAndShowGUI() {
        final DefaultMutableTreeNode root = new DefaultMutableTreeNode("Problem with NPE under JDK 1.6");
        final DefaultMutableTreeNode problematic = new DefaultMutableTreeNode("Expand me and behold a NPE in stderr");
        problematic.add(new DefaultMutableTreeNode("some content"));
        root.add(new DefaultMutableTreeNode("irrelevant..."));
        root.add(problematic);

        final DefaultTreeModel model = new DefaultTreeModel(root);
        tree = new JTree(model);
        tree.setRootVisible(true);
        tree.setShowsRootHandles(true);
        tree.expandRow(0);
        tree.collapseRow(2);

        // this is critical - without dragEnabled everything works
        tree.setDragEnabled(true);

        tree.addTreeExpansionListener(new TreeExpansionListener() {

            @Override
            public void treeExpanded(TreeExpansionEvent event) {
                TreeNode parent = problematic.getParent();
                if (parent instanceof DefaultMutableTreeNode) {
                    model.removeNodeFromParent(problematic);
                }
            }

            @Override
            public void treeCollapsed(TreeExpansionEvent event) {
            }
        });

        JFrame frame = new JFrame("JTree Problem");
        frame.add(new JScrollPane(tree));
        frame.setSize(500, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

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