8189204: Possible NPE in Component::getLocationOnScreen()

Reviewed-by: serb, prr

src/java.desktop/share/classes/java/awt/Component.java

@@ -2039,14 +2039,14 @@ public abstract class Component implements ImageObserver, MenuContainer,
      * used by GlobalCursormanager to update cursor
      */
     final Point getLocationOnScreen_NoTreeLock() {
-
+        ComponentPeer peer = this.peer;
         if (peer != null && isShowing()) {
             if (peer instanceof LightweightPeer) {
                 // lightweight component location needs to be translated
                 // relative to a native component.
                 Container host = getNativeContainer();
                 Point pt = host.peer.getLocationOnScreen();
-                for(Component c = this; c != host; c = c.getParent()) {
+                for(Component c = this; c != host; c = c.getContainer()) {
                     pt.x += c.x;
                     pt.y += c.y;
                 }

test/jdk/java/awt/Component/GetScreenLocTest/ComponentGetLocationOnScreenNPETest.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2002, 2017, 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 8189204
+ * @summary Possible NPE in Component::getLocationOnScreen()
+ * @run main ComponentGetLocationOnScreenNPETest
+ */
+
+import javax.swing.*;
+import java.awt.*;
+
+public class ComponentGetLocationOnScreenNPETest {
+
+    private static Frame frame;
+    private static JPanel panel;
+
+    public static void main(String[] args) throws Exception {
+        SwingUtilities.invokeAndWait(() -> {
+            frame = new Frame();
+            JPanel parentPanel = new JPanel() {
+                @Override
+                public Container getParent() {
+                    return new Frame();
+                }
+            };
+            frame.add(parentPanel);
+            panel = new JPanel();
+            parentPanel.add(panel);
+            frame.setVisible(true);
+        });
+        Robot robot = new Robot();
+        robot.waitForIdle();
+        robot.delay(200);
+
+        SwingUtilities.invokeAndWait(panel::getLocationOnScreen);
+        SwingUtilities.invokeLater(frame::dispose);
+    }
+}