Add better index checks for AndroidCharacter.mirror

Fix potential invalid array access if start index is before the
beginning of the array or start + count is past the end of the array.
Update Javadoc for mirror to reflect the usage of "start" and "count".

Change-Id: I7e596de8eae5c518a2b4ff0d28604bd9c59f9d9d

1 files changed, 5 insertions, 0 deletions

diff --git a/core/java/android/text/AndroidCharacter.java b/core/java/android/text/AndroidCharacter.java
index af93b5d3772b..05887c551d8d 100644
--- a/core/java/android/text/AndroidCharacter.java
+++ b/core/java/android/text/AndroidCharacter.java
@@ -73,6 +73,11 @@ public class AndroidCharacter
      * Replace the specified slice of <code>text</code> with the chars'
      * right-to-left mirrors (if any), returning true if any
      * replacements were made.
+     *
+     * @param text array of characters to apply mirror operation
+     * @param start first character in array to mirror
+     * @param count maximum number of characters to mirror
+     * @return true if replacements were made
      */
     public native static boolean mirror(char[] text, int start, int count);