Applying my second patch from LANG-360 - it seems to do what Stephane/Paul and I are consensing on

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@594336 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/lang/ObjectUtils.java

@@ -157,7 +157,33 @@ public class ObjectUtils {
         if (object == null) {
             return null;
         }
-        return appendIdentityToString(null, object).toString();
+        StringBuffer buffer = new StringBuffer();
+        identityToString(buffer, object);
+        return buffer.toString();
+    }
+
+    /**
+     * <p>Appends the toString that would be produced by <code>Object</code>
+     * if a class did not override toString itself. <code>null</code>
+     * will throw a NullPointerException for either of the two parameters. </p>
+     *
+     * <pre>
+     * ObjectUtils.identityToString(buf, "")            = buf.append("java.lang.String@1e23"
+     * ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa"
+     * ObjectUtils.identityToString(buf, Boolean.TRUE)  = buf.append("java.lang.Boolean@7fa")
+     * </pre>
+     *
+     * @param buffer  the buffer to append to
+     * @param object  the object to create a toString for
+     * @since 2.4
+     */
+    public static void identityToString(StringBuffer buffer, Object object) {
+        if (object == null) {
+            throw new NullPointerException("Cannot get the toString of a null identity");
+        }
+        buffer.append(object.getClass().getName())
+              .append('@')
+              .append(Integer.toHexString(System.identityHashCode(object)));
     }
 
     /**
@@ -177,6 +203,7 @@ public class ObjectUtils {
      * @return the default toString text, or <code>null</code> if
      *  <code>null</code> passed in
      * @since 2.0
+     * @deprecated The design of this method is bad - see LANG-360. Instead, use identityToString(StringBuffer, Object).
      */
     public static StringBuffer appendIdentityToString(StringBuffer buffer, Object object) {
         if (object == null) {

src/test/org/apache/commons/lang/ObjectUtilsTest.java

@@ -138,9 +138,22 @@ public class ObjectUtilsTest extends TestCase {
             "java.lang.String@" + Integer.toHexString(System.identityHashCode(FOO)),
             ObjectUtils.identityToString(FOO));
         Integer i = new Integer(90);
-        assertEquals(
-            "java.lang.Integer@" + Integer.toHexString(System.identityHashCode(i)),
-            ObjectUtils.identityToString(i));
+        String expected = "java.lang.Integer@" + Integer.toHexString(System.identityHashCode(i));
+        assertEquals(expected, ObjectUtils.identityToString(i));
+        StringBuffer buffer = new StringBuffer();
+        ObjectUtils.identityToString(buffer, i);
+        assertEquals(expected, buffer.toString());
+
+        try {
+            ObjectUtils.identityToString(null, "tmp");
+            fail("NullPointerException expected");
+        } catch(NullPointerException npe) {
+        }
+        try {
+            ObjectUtils.identityToString(new StringBuffer(), null);
+            fail("NullPointerException expected");
+        } catch(NullPointerException npe) {
+        }
     }
 
     public void testAppendIdentityToString() {