4339584: Adding a getUI public method to JComponent

Reviewed-by: azvegint, alexsch

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

@@ -617,6 +617,15 @@ public abstract class JComponent extends Container implements Serializable,
      */
     public void updateUI() {}
 
+    /**
+     * Returns the look and feel delegate that renders this component.
+     *
+     * @return the {@code ComponentUI} object that renders this component
+     * @since 1.9
+     */
+    public ComponentUI getUI() {
+        return ui;
+    }
 
     /**
      * Sets the look and feel delegate for this component.

jdk/test/javax/swing/JComponent/4339584/GetUI.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2015, 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 javax.swing.JComponent;
+import javax.swing.plaf.ComponentUI;
+
+/**
+ * @test
+ * @bug 4339584
+ */
+public final class GetUI {
+
+    public static void main(final String[] args) {
+        CustomJComponent component = new CustomJComponent();
+        ComponentUI ui = new ComponentUI() {
+        };
+        component.setUI(ui);
+        ComponentUI actual = component.getUI();
+        if (actual != ui) {
+            System.err.println("Expected: " + ui);
+            System.err.println("Actual: " + actual);
+            throw new RuntimeException("Test failed");
+        }
+    }
+
+    private static class CustomJComponent extends JComponent {
+
+        @Override
+        public ComponentUI getUI() {
+            return super.getUI();
+        }
+
+        @Override
+        public void setUI(ComponentUI ui) {
+            super.setUI(ui);
+        }
+    }
+}