Continue error check improvements and write some docs.

Change-Id: I345b08490da21d9ee715ff1ddc80c1a816b579f4
diff --git a/graphics/java/android/renderscript/ProgramFragment.java b/graphics/java/android/renderscript/ProgramFragment.java
index 8858b74..d30e483 100644
--- a/graphics/java/android/renderscript/ProgramFragment.java
+++ b/graphics/java/android/renderscript/ProgramFragment.java
@@ -42,15 +42,15 @@
 
             for (int i=0; i < mInputCount; i++) {
                 tmp[idx++] = 0;
-                tmp[idx++] = mInputs[i].mID;
+                tmp[idx++] = mInputs[i].getID();
             }
             for (int i=0; i < mOutputCount; i++) {
                 tmp[idx++] = 1;
-                tmp[idx++] = mOutputs[i].mID;
+                tmp[idx++] = mOutputs[i].getID();
             }
             for (int i=0; i < mConstantCount; i++) {
                 tmp[idx++] = 2;
-                tmp[idx++] = mConstants[i].mID;
+                tmp[idx++] = mConstants[i].getID();
             }
             tmp[idx++] = 3;
             tmp[idx++] = mTextureCount;