Document the order of values returned by keyAt().

The values returned by keyAt() are currently guaranteed to be in
ascending order. This is helpful to users of the API to be able to make
assumptions about the keys and values when iterating over one of the
sparse array implementations.

This commit adds documentation about this.

Change-Id: I3d7eb78e115ce174f1167b83904b44bf5120b223

core/java/android/util/LongSparseArray.java

@@ -39,6 +39,12 @@ import com.android.internal.util.ArrayUtils;
  * a single garbage collection step of all removed entries.  This garbage collection will
  * need to be performed at any time the array needs to be grown or the the map size or
  * entry values are retrieved.</p>
+ *
+ * <p>It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * <code>keyAt(int)</code> with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of <code>valueAt(int)<code>.</p>
  */
 public class LongSparseArray<E> implements Cloneable {
     private static final Object DELETED = new Object();
@@ -238,6 +244,11 @@ public class LongSparseArray<E> implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the key from the <code>index</code>th key-value mapping that this
      * LongSparseArray stores.
+     *
+     * <p>The keys corresponding to indices in ascending order are guaranteed to
+     * be in ascending order, e.g., <code>keyAt(0)</code> will return the
+     * smallest key and <code>keyAt(size()-1)</code> will return the largest
+     * key.</p>
      */
     public long keyAt(int index) {
         if (mGarbage) {
@@ -251,6 +262,12 @@ public class LongSparseArray<E> implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the value from the <code>index</code>th key-value mapping that this
      * LongSparseArray stores.
+     *
+     * <p>The values corresponding to indices in ascending order are guaranteed
+     * to be associated with keys in ascending order, e.g.,
+     * <code>valueAt(0)</code> will return the value associated with the
+     * smallest key and <code>valueAt(size()-1)</code> will return the value
+     * associated with the largest key.</p>
      */
     @SuppressWarnings("unchecked")
     public E valueAt(int index) {

core/java/android/util/LongSparseLongArray.java

@@ -35,6 +35,12 @@ import java.util.Arrays;
  * and deleting entries in the array.  For containers holding up to hundreds of items,
  * the performance difference is not significant, less than 50%.</p>
  *
+ * <p>It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * <code>keyAt(int)</code> with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of <code>valueAt(int)<code>.</p>
+ *
  * @hide
  */
 public class LongSparseLongArray implements Cloneable {
@@ -163,6 +169,11 @@ public class LongSparseLongArray implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the key from the <code>index</code>th key-value mapping that this
      * SparseLongArray stores.
+     *
+     * <p>The keys corresponding to indices in ascending order are guaranteed to
+     * be in ascending order, e.g., <code>keyAt(0)</code> will return the
+     * smallest key and <code>keyAt(size()-1)</code> will return the largest
+     * key.</p>
      */
     public long keyAt(int index) {
         return mKeys[index];
@@ -172,6 +183,12 @@ public class LongSparseLongArray implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the value from the <code>index</code>th key-value mapping that this
      * SparseLongArray stores.
+     *
+     * <p>The values corresponding to indices in ascending order are guaranteed
+     * to be associated with keys in ascending order, e.g.,
+     * <code>valueAt(0)</code> will return the value associated with the
+     * smallest key and <code>valueAt(size()-1)</code> will return the value
+     * associated with the largest key.</p>
      */
     public long valueAt(int index) {
         return mValues[index];

core/java/android/util/SparseArray.java

@@ -39,6 +39,12 @@ import com.android.internal.util.ArrayUtils;
  * a single garbage collection step of all removed entries.  This garbage collection will
  * need to be performed at any time the array needs to be grown or the the map size or
  * entry values are retrieved.</p>
+ *
+ * <p>It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * <code>keyAt(int)</code> with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of <code>valueAt(int)<code>.</p>
  */
 public class SparseArray<E> implements Cloneable {
     private static final Object DELETED = new Object();
@@ -251,6 +257,11 @@ public class SparseArray<E> implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the key from the <code>index</code>th key-value mapping that this
      * SparseArray stores.
+     *
+     * <p>The keys corresponding to indices in ascending order are guaranteed to
+     * be in ascending order, e.g., <code>keyAt(0)</code> will return the
+     * smallest key and <code>keyAt(size()-1)</code> will return the largest
+     * key.</p>
      */
     public int keyAt(int index) {
         if (mGarbage) {
@@ -264,6 +275,12 @@ public class SparseArray<E> implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the value from the <code>index</code>th key-value mapping that this
      * SparseArray stores.
+     *
+     * <p>The values corresponding to indices in ascending order are guaranteed
+     * to be associated with keys in ascending order, e.g.,
+     * <code>valueAt(0)</code> will return the value associated with the
+     * smallest key and <code>valueAt(size()-1)</code> will return the value
+     * associated with the largest key.</p>
      */
     @SuppressWarnings("unchecked")
     public E valueAt(int index) {

core/java/android/util/SparseBooleanArray.java

@@ -33,6 +33,12 @@ import com.android.internal.util.ArrayUtils;
  * HashMap, since lookups require a binary search and adds and removes require inserting
  * and deleting entries in the array.  For containers holding up to hundreds of items,
  * the performance difference is not significant, less than 50%.</p>
+ *
+ * <p>It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * <code>keyAt(int)</code> with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of <code>valueAt(int)<code>.</p>
  */
 public class SparseBooleanArray implements Cloneable {
     /**
@@ -159,16 +165,27 @@ public class SparseBooleanArray implements Cloneable {
     /**
      * Given an index in the range <code>0...size()-1</code>, returns
      * the key from the <code>index</code>th key-value mapping that this
-     * SparseBooleanArray stores.  
+     * SparseBooleanArray stores.
+     *
+     * <p>The keys corresponding to indices in ascending order are guaranteed to
+     * be in ascending order, e.g., <code>keyAt(0)</code> will return the
+     * smallest key and <code>keyAt(size()-1)</code> will return the largest
+     * key.</p>
      */
     public int keyAt(int index) {
         return mKeys[index];
     }
-    
+
     /**
      * Given an index in the range <code>0...size()-1</code>, returns
      * the value from the <code>index</code>th key-value mapping that this
-     * SparseBooleanArray stores.  
+     * SparseBooleanArray stores.
+     *
+     * <p>The values corresponding to indices in ascending order are guaranteed
+     * to be associated with keys in ascending order, e.g.,
+     * <code>valueAt(0)</code> will return the value associated with the
+     * smallest key and <code>valueAt(size()-1)</code> will return the value
+     * associated with the largest key.</p>
      */
     public boolean valueAt(int index) {
         return mValues[index];

core/java/android/util/SparseIntArray.java

@@ -32,6 +32,12 @@ import com.android.internal.util.ArrayUtils;
  * HashMap, since lookups require a binary search and adds and removes require inserting
  * and deleting entries in the array.  For containers holding up to hundreds of items,
  * the performance difference is not significant, less than 50%.</p>
+ *
+ * <p>It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * <code>keyAt(int)</code> with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of <code>valueAt(int)<code>.</p>
  */
 public class SparseIntArray implements Cloneable {
     private int[] mKeys;
@@ -169,16 +175,27 @@ public class SparseIntArray implements Cloneable {
     /**
      * Given an index in the range <code>0...size()-1</code>, returns
      * the key from the <code>index</code>th key-value mapping that this
-     * SparseIntArray stores.  
+     * SparseIntArray stores.
+     *
+     * <p>The keys corresponding to indices in ascending order are guaranteed to
+     * be in ascending order, e.g., <code>keyAt(0)</code> will return the
+     * smallest key and <code>keyAt(size()-1)</code> will return the largest
+     * key.</p>
      */
     public int keyAt(int index) {
         return mKeys[index];
     }
-    
+
     /**
      * Given an index in the range <code>0...size()-1</code>, returns
      * the value from the <code>index</code>th key-value mapping that this
-     * SparseIntArray stores.  
+     * SparseIntArray stores.
+     *
+     * <p>The values corresponding to indices in ascending order are guaranteed
+     * to be associated with keys in ascending order, e.g.,
+     * <code>valueAt(0)</code> will return the value associated with the
+     * smallest key and <code>valueAt(size()-1)</code> will return the value
+     * associated with the largest key.</p>
      */
     public int valueAt(int index) {
         return mValues[index];

core/java/android/util/SparseLongArray.java

@@ -32,6 +32,12 @@ import com.android.internal.util.ArrayUtils;
  * HashMap, since lookups require a binary search and adds and removes require inserting
  * and deleting entries in the array.  For containers holding up to hundreds of items,
  * the performance difference is not significant, less than 50%.</p>
+ *
+ * <p>It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * <code>keyAt(int)</code> with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of <code>valueAt(int)<code>.</p>
  */
 public class SparseLongArray implements Cloneable {
     private int[] mKeys;
@@ -159,6 +165,11 @@ public class SparseLongArray implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the key from the <code>index</code>th key-value mapping that this
      * SparseLongArray stores.
+     *
+     * <p>The keys corresponding to indices in ascending order are guaranteed to
+     * be in ascending order, e.g., <code>keyAt(0)</code> will return the
+     * smallest key and <code>keyAt(size()-1)</code> will return the largest
+     * key.</p>
      */
     public int keyAt(int index) {
         return mKeys[index];
@@ -168,6 +179,12 @@ public class SparseLongArray implements Cloneable {
      * Given an index in the range <code>0...size()-1</code>, returns
      * the value from the <code>index</code>th key-value mapping that this
      * SparseLongArray stores.
+     *
+     * <p>The values corresponding to indices in ascending order are guaranteed
+     * to be associated with keys in ascending order, e.g.,
+     * <code>valueAt(0)</code> will return the value associated with the
+     * smallest key and <code>valueAt(size()-1)</code> will return the value
+     * associated with the largest key.</p>
      */
     public long valueAt(int index) {
         return mValues[index];