Fix documentation in SparseSetArray.

"n" in SparseSetArray is actually the key, not the index. "index" is used
as a parameter name in this class wherever it actually is the index.
Using index in documentation in the wrong places gives users the wrong
understanding.

Bug: N/A
Test: N/A
Change-Id: I239a653347dab4ea1a00c6d709aac06a98012a46
diff --git a/core/java/android/util/SparseSetArray.java b/core/java/android/util/SparseSetArray.java
index c1873d7..9f0f246 100644
--- a/core/java/android/util/SparseSetArray.java
+++ b/core/java/android/util/SparseSetArray.java
@@ -27,8 +27,8 @@
     }
 
     /**
-     * Add a value at index n.
-     * @return FALSE when the value already existed at the given index, TRUE otherwise.
+     * Add a value for key n.
+     * @return FALSE when the value already existed for the given key, TRUE otherwise.
      */
     public boolean add(int n, T value) {
         ArraySet<T> set = mData.get(n);
@@ -51,7 +51,7 @@
     }
 
     /**
-     * @return whether a value exists at index n.
+     * @return whether the value exists for the key n.
      */
     public boolean contains(int n, T value) {
         final ArraySet<T> set = mData.get(n);
@@ -62,15 +62,15 @@
     }
 
     /**
-     * @return the set of items at index n
+     * @return the set of items of key n
      */
     public ArraySet<T> get(int n) {
         return mData.get(n);
     }
 
     /**
-     * Remove a value from index n.
-     * @return TRUE when the value existed at the given index and removed, FALSE otherwise.
+     * Remove a value for key n.
+     * @return TRUE when the value existed for the given key and removed, FALSE otherwise.
      */
     public boolean remove(int n, T value) {
         final ArraySet<T> set = mData.get(n);
@@ -85,7 +85,7 @@
     }
 
     /**
-     * Remove all values from index n.
+     * Remove all values for key n.
      */
     public void remove(int n) {
         mData.remove(n);