5078989: Null Pointer exception in SpinnerListMode

Reviewed-by: serb

src/java.desktop/share/classes/javax/swing/SpinnerListModel.java

@@ -236,10 +236,12 @@ public class SpinnerListModel extends AbstractSpinnerModel implements Serializab
 
         do {
             Object value = list.get(counter);
-            String string = value.toString();
+            if (value != null) {
+                String string = value.toString();
 
-            if (string != null && string.startsWith(substring)) {
-                return value;
+                if (string != null && string.startsWith(substring)) {
+                    return value;
+                }
             }
             counter = (counter + 1) % max;
         } while (counter != index);

test/jdk/javax/swing/JSpinner/SpinnerTest.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2020, 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 5078989
+   @key headful
+   @summary Verifies Null Pointer exception is not thrown in SpinnerListMode
+   @run main SpinnerTest
+ */
+import javax.swing.JFrame;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JSpinner;
+import javax.swing.SpinnerListModel;
+import javax.swing.SwingUtilities;
+import java.awt.event.KeyEvent;
+import java.awt.Point;
+import java.awt.Robot;
+
+public class SpinnerTest
+{
+    private static JFrame frame;
+    private static JSpinner spinner;
+
+    public static void main(String[] args) throws Exception {
+        Robot robot = new Robot();
+        robot.setAutoDelay(100);
+        try {
+            SwingUtilities.invokeAndWait(() -> {
+                //Create and set up the window.
+                frame = new JFrame("SpinnerDemo");
+                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+
+                JPanel panel = new JPanel();
+                String[] values = {"Month: ", "Year: ", null, "Date", "Sent"};
+
+                SpinnerListModel listModel = new SpinnerListModel(values);
+
+                JLabel l = new JLabel("Spinner");
+                panel.add(l);
+
+                spinner = new JSpinner(listModel);
+                l.setLabelFor(spinner);
+                panel.add(spinner);
+
+                panel.setOpaque(true); //content panes must be opaque
+                frame.setContentPane(panel);
+
+                //Display the window.
+                frame.pack();
+                frame.setVisible(true);
+                frame.setLocationRelativeTo(null);
+            });
+            robot.waitForIdle();
+            robot.delay(1000);
+            Point loc = spinner.getLocationOnScreen();
+
+            robot.mouseMove(loc.x, loc.y);
+            robot.keyPress(KeyEvent.VK_SPACE);
+            robot.keyRelease(KeyEvent.VK_SPACE);
+
+        } finally {
+            if (frame != null) {
+                SwingUtilities.invokeAndWait(() -> frame.dispose());
+            }
+        }
+    }
+}