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10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
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20  * or visit www.oracle.com if you need additional information or have any
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23 
24 /*
25  * @test
26  * @bug 6505523
27  * @summary NullPointerException in BasicTreeUI when a node is removed by expansion listener
28  * @author Alexandr Scherbatiy
29  * @run main bug6505523
30  */
31 import java.awt.Point;
32 import java.awt.Rectangle;
33 import java.awt.Robot;
34 import java.awt.event.InputEvent;
35 import javax.swing.JFrame;
36 import javax.swing.JScrollPane;
37 import javax.swing.JTree;
38 import javax.swing.SwingUtilities;
39 import javax.swing.event.TreeExpansionEvent;
40 import javax.swing.event.TreeExpansionListener;
41 import javax.swing.tree.DefaultMutableTreeNode;
42 import javax.swing.tree.DefaultTreeModel;
43 import javax.swing.tree.TreeNode;
44 
45 public class bug6505523 {
46 
47     private static JTree tree;
48 
main(String[] args)49     public static void main(String[] args) throws Exception {
50         Robot robot = new Robot();
51         robot.setAutoDelay(50);
52 
53         SwingUtilities.invokeAndWait(new Runnable() {
54 
55             @Override
56             public void run() {
57                 createAndShowGUI();
58             }
59         });
60 
61         robot.waitForIdle();
62 
63         Point point = getRowPointToClick(2);
64         robot.mouseMove(point.x, point.y);
65         robot.mousePress(InputEvent.BUTTON1_MASK);
66         robot.mouseRelease(InputEvent.BUTTON1_MASK);
67 
68         robot.waitForIdle();
69 
70     }
71 
getRowPointToClick(final int row)72     private static Point getRowPointToClick(final int row) throws Exception {
73 
74         final Point[] result = new Point[1];
75 
76         SwingUtilities.invokeAndWait(new Runnable() {
77 
78             @Override
79             public void run() {
80                 Rectangle rect = tree.getRowBounds(row);
81                 Point point = new Point(rect.x - 5, rect.y + rect.height / 2);
82                 SwingUtilities.convertPointToScreen(point, tree);
83                 result[0] = point;
84             }
85         });
86 
87         return result[0];
88     }
89 
createAndShowGUI()90     private static void createAndShowGUI() {
91         final DefaultMutableTreeNode root = new DefaultMutableTreeNode("Problem with NPE under JDK 1.6");
92         final DefaultMutableTreeNode problematic = new DefaultMutableTreeNode("Expand me and behold a NPE in stderr");
93         problematic.add(new DefaultMutableTreeNode("some content"));
94         root.add(new DefaultMutableTreeNode("irrelevant..."));
95         root.add(problematic);
96 
97         final DefaultTreeModel model = new DefaultTreeModel(root);
98         tree = new JTree(model);
99         tree.setRootVisible(true);
100         tree.setShowsRootHandles(true);
101         tree.expandRow(0);
102         tree.collapseRow(2);
103 
104         // this is critical - without dragEnabled everything works
105         tree.setDragEnabled(true);
106 
107         tree.addTreeExpansionListener(new TreeExpansionListener() {
108 
109             @Override
110             public void treeExpanded(TreeExpansionEvent event) {
111                 TreeNode parent = problematic.getParent();
112                 if (parent instanceof DefaultMutableTreeNode) {
113                     model.removeNodeFromParent(problematic);
114                 }
115             }
116 
117             @Override
118             public void treeCollapsed(TreeExpansionEvent event) {
119             }
120         });
121 
122         JFrame frame = new JFrame("JTree Problem");
123         frame.add(new JScrollPane(tree));
124         frame.setSize(500, 300);
125         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
126         frame.setLocationRelativeTo(null);
127         frame.setVisible(true);
128     }
129 }
130