8074883: Tab key should move to focused button in a button group

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

@@ -7759,6 +7759,15 @@ private boolean isRequestFocusAccepted(boolean temporary,
             }
         }
 
+        boolean ret = Component.requestFocusController.acceptRequestFocus(focusOwner,
+                                                                          this,
+                                                                          temporary,
+                                                                          focusedWindowChangeAllowed,
+                                                                          cause);
+        if (focusLog.isLoggable(PlatformLogger.Level.FINEST)) {
+            focusLog.finest("RequestFocusController returns {0}", ret);
+        }
+
         if (focusOwner == this || focusOwner == null) {
             // Controller is supposed to verify focus transfers and for this it
             // should know both from and to components.  And it shouldn't verify
@@ -7782,15 +7791,6 @@ private boolean isRequestFocusAccepted(boolean temporary,
             return true;
         }
 
-        boolean ret = Component.requestFocusController.acceptRequestFocus(focusOwner,
-                                                                          this,
-                                                                          temporary,
-                                                                          focusedWindowChangeAllowed,
-                                                                          cause);
-        if (focusLog.isLoggable(PlatformLogger.Level.FINEST)) {
-            focusLog.finest("RequestFocusController returns {0}", ret);
-        }
-
         return ret;
     }
 

jdk/src/share/classes/javax/swing/JComponent.java

@@ -3565,6 +3565,22 @@ public boolean acceptRequestFocus(Component from, Component to,
                     return true;
                 }
 
+                if (to instanceof JToggleButton) {
+                    JToggleButton tb = ((JToggleButton)to).getGroupSelection(cause);
+                    if (tb != to) {
+                        if (focusedWindowChangeAllowed) {
+                            SwingUtilities.invokeLater(() -> {
+                                tb.requestFocus();
+                            });
+                        } else {
+                            SwingUtilities.invokeLater(() -> {
+                                tb.requestFocusInWindow();
+                            });
+                        }
+                        return false;
+                    }
+                }
+
                 if ((from == null) || !(from instanceof JComponent)) {
                     return true;
                 }

jdk/src/share/classes/javax/swing/JToggleButton.java

@@ -35,6 +35,8 @@
 import java.io.ObjectInputStream;
 import java.io.IOException;
 
+import java.util.Enumeration;
+import sun.awt.CausedFocusEvent;
 
 /**
  * An implementation of a two-state button.
@@ -208,6 +210,41 @@ boolean shouldUpdateSelectedStateFromAction() {
         return true;
     }
 
+    JToggleButton getGroupSelection(CausedFocusEvent.Cause cause) {
+        switch (cause) {
+            case ACTIVATION:
+            case TRAVERSAL:
+            case TRAVERSAL_UP:
+            case TRAVERSAL_DOWN:
+            case TRAVERSAL_FORWARD:
+            case TRAVERSAL_BACKWARD:
+                ButtonModel model = getModel();
+                JToggleButton selection = this;
+                if (model instanceof DefaultButtonModel) {
+                    ButtonGroup group = ((DefaultButtonModel) model).getGroup();
+                    if (group != null && group.getSelection() != null
+                                                      && !group.isSelected(model)) {
+                        Enumeration<AbstractButton> iterator =
+                                                   group.getElements();
+                        while (iterator.hasMoreElements()) {
+                            AbstractButton member = iterator.nextElement();
+                            if (group.isSelected(member.getModel())) {
+                                if (member instanceof JToggleButton &&
+                                    member.isVisible() && member.isDisplayable() &&
+                                    member.isEnabled() && member.isFocusable()) {
+                                    selection = (JToggleButton) member;
+                                }
+                                break;
+                            }
+                        }
+                    }
+                }
+                return selection;
+            default:
+                return this;
+        }
+    }
+
     // *********************************************************************
 
     /**

jdk/test/javax/swing/JRadioButton/ButtonGroupFocus/ButtonGroupFocusTest.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2016, 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 8074883
+ * @summary Tab key should move to focused button in a button group
+ * @run main ButtonGroupFocusTest
+ */
+
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.KeyEvent;
+
+public class ButtonGroupFocusTest {
+
+    private static JRadioButton button1;
+    private static JRadioButton button2;
+    private static JRadioButton button3;
+    private static JRadioButton button4;
+    private static JRadioButton button5;
+    private static Robot robot;
+    private static JFrame frame;
+
+    public static void main(String[] args) throws Exception {
+        robot = new Robot();
+        robot.setAutoDelay(100);
+
+        SwingUtilities.invokeAndWait(() -> {
+            frame = new JFrame();
+            Container contentPane = frame.getContentPane();
+            contentPane.setLayout(new FlowLayout());
+            button1 = new JRadioButton("Button 1");
+            contentPane.add(button1);
+            button2 = new JRadioButton("Button 2");
+            contentPane.add(button2);
+            button3 = new JRadioButton("Button 3");
+            contentPane.add(button3);
+            button4 = new JRadioButton("Button 4");
+            contentPane.add(button4);
+            button5 = new JRadioButton("Button 5");
+            contentPane.add(button5);
+            ButtonGroup group = new ButtonGroup();
+            group.add(button1);
+            group.add(button2);
+            group.add(button3);
+
+            group = new ButtonGroup();
+            group.add(button4);
+            group.add(button5);
+
+            button2.setSelected(true);
+
+            frame.pack();
+            frame.setVisible(true);
+        });
+
+        robot.waitForIdle();
+        robot.delay(200);
+
+        SwingUtilities.invokeAndWait(() -> {
+            if( !button2.hasFocus() ) {
+                frame.dispose();
+                throw new RuntimeException(
+                        "Button 2 should get focus after activation");
+            }
+        });
+
+        robot.keyPress(KeyEvent.VK_TAB);
+        robot.keyRelease(KeyEvent.VK_TAB);
+
+        robot.waitForIdle();
+        robot.delay(200);
+
+        SwingUtilities.invokeAndWait(() -> {
+            if( !button4.hasFocus() ) {
+                frame.dispose();
+                throw new RuntimeException(
+                        "Button 4 should get focus");
+            }
+            button3.setSelected(true);
+        });
+
+        robot.keyPress(KeyEvent.VK_TAB);
+        robot.keyRelease(KeyEvent.VK_TAB);
+
+        robot.waitForIdle();
+        robot.delay(200);
+
+        SwingUtilities.invokeAndWait(() -> {
+            if( !button3.hasFocus() ) {
+                frame.dispose();
+                throw new RuntimeException(
+                        "selected Button 3 should get focus");
+            }
+        });
+
+        SwingUtilities.invokeLater(frame::dispose);
+    }
+}