8238741: java.awt.Robot(GraphicsDevice) constructor does not follow the spec

Reviewed-by: aivanov

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 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
@@ -90,9 +90,7 @@ public class Robot {
      * @see     AWTPermission
      */
     public Robot() throws AWTException {
-        if (GraphicsEnvironment.isHeadless()) {
-            throw new AWTException("headless environment");
-        }
+        checkHeadless();
         init(GraphicsEnvironment.getLocalGraphicsEnvironment()
             .getDefaultScreenDevice());
     }
@@ -125,6 +123,7 @@ public class Robot {
      * @see     AWTPermission
      */
     public Robot(GraphicsDevice screen) throws AWTException {
+        checkHeadless();
         checkIsScreenDevice(screen);
         init(screen);
     }
@@ -161,15 +160,24 @@ public class Robot {
     }
 
     /* determine if the security policy allows Robot's to be created */
-    private void checkRobotAllowed() {
+    private static void checkRobotAllowed() {
         SecurityManager security = System.getSecurityManager();
         if (security != null) {
             security.checkPermission(AWTPermissions.CREATE_ROBOT_PERMISSION);
         }
     }
 
+    /**
+     * Check for headless state and throw {@code AWTException} if headless.
+     */
+    private static void checkHeadless() throws AWTException {
+        if (GraphicsEnvironment.isHeadless()) {
+            throw new AWTException("headless environment");
+        }
+    }
+
     /* check if the given device is a screen device */
-    private void checkIsScreenDevice(GraphicsDevice device) {
+    private static void checkIsScreenDevice(GraphicsDevice device) {
         if (device == null || device.getType() != GraphicsDevice.TYPE_RASTER_SCREEN) {
             throw new IllegalArgumentException("not a valid screen device");
         }
@@ -300,7 +308,7 @@ public class Robot {
         afterEvent();
     }
 
-    private void checkButtonsArgument(int buttons) {
+    private static void checkButtonsArgument(int buttons) {
         if ( (buttons|LEGAL_BUTTON_MASK) != LEGAL_BUTTON_MASK ) {
             throw new IllegalArgumentException("Invalid combination of button flags");
         }
@@ -359,7 +367,7 @@ public class Robot {
         afterEvent();
     }
 
-    private void checkKeycodeArgument(int keycode) {
+    private static void checkKeycodeArgument(int keycode) {
         // rather than build a big table or switch statement here, we'll
         // just check that the key isn't VK_UNDEFINED and assume that the
         // peer implementations will throw an exception for other bogus
@@ -664,7 +672,7 @@ public class Robot {
         }
     }
 
-    private void checkDelayArgument(int ms) {
+    private static void checkDelayArgument(int ms) {
         if (ms < 0 || ms > MAX_DELAY) {
             throw new IllegalArgumentException("Delay must be to 0 to 60,000ms");
         }
@@ -680,7 +688,7 @@ public class Robot {
         ((SunToolkit) Toolkit.getDefaultToolkit()).realSync();
     }
 
-    private void checkNotDispatchThread() {
+    private static void checkNotDispatchThread() {
         if (EventQueue.isDispatchThread()) {
             throw new IllegalThreadStateException("Cannot call method from the event dispatcher thread");
         }

test/jdk/java/awt/Headless/HeadlessRobot.java

@@ -0,0 +1,73 @@
+/*
+ * 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.
+ */
+
+import java.awt.AWTException;
+import java.awt.GraphicsConfiguration;
+import java.awt.GraphicsDevice;
+import java.awt.Robot;
+
+/**
+ * @test
+ * @bug 8238741
+ * @summary Check that Robot constructors throw AWTException in a headless
+ *          environment
+ * @run main/othervm -Djava.awt.headless=true HeadlessRobot
+ */
+public final class HeadlessRobot {
+
+    public static void main(String[] args) {
+        try {
+            new Robot();
+            throw new RuntimeException("Expected AWTException did not occur");
+        } catch (AWTException ignored) {
+            // expected AWTException
+        }
+
+        try {
+            new Robot(new GraphicsDevice() {
+                @Override
+                public int getType() {
+                    return TYPE_RASTER_SCREEN;
+                }
+
+                @Override
+                public String getIDstring() {
+                    return "Stub device";
+                }
+
+                @Override
+                public GraphicsConfiguration[] getConfigurations() {
+                    return null;
+                }
+
+                @Override
+                public GraphicsConfiguration getDefaultConfiguration() {
+                    return null;
+                }
+            });
+            throw new RuntimeException("Expected AWTException did not occur");
+        } catch (AWTException ignored) {
+            // expected AWTException
+        }
+    }
+}