4245470: algorithm of java.lang.Byte.hashCode() is not specified

Specify some hashCode methods are equivalent to intValue

Reviewed-by: darcy

jdk/src/share/classes/java/lang/Byte.java

@@ -378,7 +378,10 @@ public final class Byte extends Number implements Comparable<Byte> {
     }
 
     /**
-     * Returns a hash code for this {@code Byte}.
+     * Returns a hash code for this {@code Byte}; equal to the result
+     * of invoking {@code intValue()}.
+     *
+     * @return a hash code value for this {@code Byte}
      */
     public int hashCode() {
         return (int)value;

jdk/src/share/classes/java/lang/Character.java

@@ -2612,8 +2612,10 @@ class Character extends Object implements java.io.Serializable, Comparable<Chara
     }
 
     /**
-     * Returns a hash code for this <code>Character</code>.
-     * @return  a hash code value for this object.
+     * Returns a hash code for this {@code Character}; equal to the result
+     * of invoking {@code charValue()}.
+     *
+     * @return a hash code value for this {@code Character}
      */
     public int hashCode() {
         return (int)value;

jdk/src/share/classes/java/lang/Short.java

@@ -383,7 +383,10 @@ public final class Short extends Number implements Comparable<Short> {
     }
 
     /**
-     * Returns a hash code for this {@code Short}.
+     * Returns a hash code for this {@code Short}; equal to the result
+     * of invoking {@code intValue()}.
+     *
+     * @return a hash code value for this {@code Short}
      */
     public int hashCode() {
         return (int)value;

jdk/test/java/lang/HashCode.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2009 Google, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug 4245470
+ * @summary Test the primitive wrappers hashCode()
+ */
+
+import java.util.Random;
+
+public class HashCode {
+
+    final Random rnd = new Random();
+
+    void test(String args[]) throws Exception {
+        int[] ints = {
+            Integer.MIN_VALUE,
+            Short.MIN_VALUE,
+            Character.MIN_VALUE,
+            Byte.MIN_VALUE,
+            -1, 0, 1,
+            Byte.MAX_VALUE,
+            Character.MAX_VALUE,
+            Short.MAX_VALUE,
+            Integer.MAX_VALUE,
+            rnd.nextInt(),
+        };
+
+        for (int x : ints) {
+            check(    new Long(x).hashCode() == (int)((long)x ^ (long)x>>>32));
+            check(Long.valueOf(x).hashCode() == (int)((long)x ^ (long)x>>>32));
+            check(    new Integer(x).hashCode() == x);
+            check(Integer.valueOf(x).hashCode() == x);
+            check(    new Short((short)x).hashCode() == (short) x);
+            check(Short.valueOf((short)x).hashCode() == (short) x);
+            check(    new Character((char) x).hashCode() == (char) x);
+            check(Character.valueOf((char) x).hashCode() == (char) x);
+            check(    new Byte((byte) x).hashCode() == (byte) x);
+            check(Byte.valueOf((byte) x).hashCode() == (byte) x);
+        }
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    volatile int passed = 0, failed = 0;
+    void pass() {passed++;}
+    void fail() {failed++; Thread.dumpStack();}
+    void fail(String msg) {System.err.println(msg); fail();}
+    void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    void check(boolean cond) {if (cond) pass(); else fail();}
+    void equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) pass();
+        else fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        new HashCode().instanceMain(args);}
+    public void instanceMain(String[] args) throws Throwable {
+        try {test(args);} catch (Throwable t) {unexpected(t);}
+        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}