API review cleanup.

Change-Id: Ieae7d450308b5637ed4253fe9baed3634c6ed141
diff --git a/graphics/java/android/renderscript/BaseObj.java b/graphics/java/android/renderscript/BaseObj.java
index 78b5617..c02435f 100644
--- a/graphics/java/android/renderscript/BaseObj.java
+++ b/graphics/java/android/renderscript/BaseObj.java
@@ -48,13 +48,19 @@
      *
      * @return int
      */
-    public int getID() {
+    int getID() {
         if (mDestroyed) {
             throw new RSInvalidStateException("using a destroyed object.");
         }
         return mID;
     }
 
+    void checkValid() {
+        if (mID == 0) {
+            throw new RSIllegalArgumentException("Invalid object.");
+        }
+    }
+
     private int mID;
     private boolean mDestroyed;
     private String mName;