8005042: Add Method.isDefault to core reflection

Reviewed-by: alanb, forax, mduigou, jgish, mchung

jdk/src/share/classes/java/lang/reflect/Method.java

@@ -504,6 +504,22 @@ public final class Method extends Executable {
         return super.isSynthetic();
     }
 
+    /**
+     * Returns {@code true} if this method is a default
+     * method; returns {@code false} otherwise.
+     *
+     * A default method is a non-abstract method, that is, a method
+     * with a body, declared in an interface type.
+     *
+     * @return true if and only if this method is a default
+     * method as defined by the Java Language Specification.
+     * @since 1.8
+     */
+    public boolean isDefault() {
+        return (getModifiers() & Modifier.ABSTRACT) == 0 &&
+            getDeclaringClass().isInterface();
+    }
+
     // NOTE that there is no synchronization used here. It is correct
     // (though not efficient) to generate more than one MethodAccessor
     // for a given Method. However, avoiding synchronization will

jdk/test/java/lang/reflect/Method/IsDefaultTest.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2012 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 8005042
+ * @summary Check behavior of Method.isDefault
+ * @author Joseph D. Darcy
+ */
+
+import java.lang.reflect.*;
+import java.lang.annotation.*;
+import java.util.*;
+
+public class IsDefaultTest {
+    public static void main(String... argv) throws Exception {
+        int failures = 0;
+        int visitationCount = 0;
+
+        List<Class<?>> classList = new ArrayList<>();
+        classList.add(TestType1.class);
+        classList.add(TestType2.class);
+        classList.add(TestType3.class);
+        classList.add(TestType4.class);
+
+        for(Class<?> clazz: classList) {
+            for(Method method: clazz.getDeclaredMethods()) {
+                ExpectedIsDefault expectedIsDefault = method.getAnnotation(ExpectedIsDefault.class);
+                if (expectedIsDefault != null) {
+                    visitationCount++;
+                    boolean expected = expectedIsDefault.value();
+                    boolean actual   = method.isDefault();
+
+                    if (actual != expected) {
+                        failures++;
+                        System.err.printf("ERROR: On %s expected isDefault of ''%s''; got ''%s''.\n",
+                                          method.toString(), expected, actual);
+                    }
+                }
+            }
+        }
+
+        if (visitationCount == 0) {
+            System.err.println("Test failed because no methods checked.");
+            throw new RuntimeException();
+        }
+
+        if (failures > 0) {
+            System.err.println("Test failed.");
+            throw new RuntimeException();
+        }
+    }
+}
+
+interface TestType1 {
+    @ExpectedIsDefault(false)
+    void foo();
+
+    @ExpectedIsDefault(true)
+    default void bar() {}; // Default method
+}
+
+class TestType2 {
+    @ExpectedIsDefault(false)
+    void bar() {};
+}
+
+class TestType3 implements TestType1 {
+    @ExpectedIsDefault(false)
+    public void foo(){}
+
+    @ExpectedIsDefault(false)
+    @Override
+    public void bar() {};
+}
+
+@interface TestType4 {
+    @ExpectedIsDefault(false)
+    String value();
+
+    @ExpectedIsDefault(false)
+    String anotherValue() default "";
+}
+
+@Retention(RetentionPolicy.RUNTIME)
+@interface ExpectedIsDefault {
+    boolean value();
+}