From b64f69cb00a5f39cc7fe93b082ddbd2e2ca4087e Mon Sep 17 00:00:00 2001
From: Inderjeet Singh <inder123@gmail.com>
Date: Mon, 1 Nov 2010 16:00:01 +0000
Subject: [PATCH] Added efficient equals and isValid static methods.

---
 .../gson/webservice/definition/rest/Id.java   | 22 ++++++++++++++++++-
 .../webservice/definition/rest/IdTest.java    | 11 ++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/rest/Id.java b/wsdef/src/main/java/com/google/gson/webservice/definition/rest/Id.java
index 3b1cae01..801baf3a 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/rest/Id.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/rest/Id.java
@@ -53,7 +53,27 @@ public final class Id<R> {
     return (int) value;
   }
 
-  @Override
+  public static boolean isValid(Id<?> id) {
+    return id != null && id.value != NULL_VALUE;
+  }
+
+  /**
+   * A more efficient comparison method for ids that take into account of ids being nullable.
+   * Since the method is parameterized and both ids are of the same type, this method compares
+   * only id values, not their types. Note that this shortcut doesn't work if you pass raw ids
+   * to this method
+   */
+  public static <T> boolean equals(/* @Nullable */ Id<T> id1, /* @Nullable */ Id<T> id2) {
+    if ((id1 == null && id2 != null) || (id1 != null && id2 == null)) {
+      return false;
+    }
+    if (id1 == null && id2 == null) {
+      return true;
+    }
+    return id1.value == id2.value;
+  }
+
+  @Override  
   public boolean equals(Object obj) {
     if (this == obj) return true;
     if (obj == null) return false;
diff --git a/wsdef/src/test/java/com/google/gson/webservice/definition/rest/IdTest.java b/wsdef/src/test/java/com/google/gson/webservice/definition/rest/IdTest.java
index 4c41a01a..1f9ddd38 100644
--- a/wsdef/src/test/java/com/google/gson/webservice/definition/rest/IdTest.java
+++ b/wsdef/src/test/java/com/google/gson/webservice/definition/rest/IdTest.java
@@ -38,6 +38,17 @@ public class IdTest extends TestCase {
     assertTrue(Id.areEquivalentTypes(fooType, Id.class));
   }
 
+  public void testStaticEquals() {
+    Id<Foo> id1 = Id.get(3L, Foo.class);
+    Id<Foo> id2 = Id.get(3L, Foo.class);
+    Id<Foo> id3 = Id.get(4L, Foo.class);
+    assertTrue(Id.equals(id1, id2));
+    assertFalse(Id.equals(null, id2));
+    assertFalse(Id.equals(id1, null));
+    assertTrue(Id.equals(null, null));
+    assertFalse(Id.equals(id1, id3));
+  }
+
   private static class Foo {
   }
 }