2 files changed, 12 insertions, 0 deletions
diff --git a/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java b/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java
index 98f0d8b68..cc25102ce 100644
--- a/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/CollectionUtils.java
@@ -18,6 +18,7 @@ package com.android.inputmethod.latin.utils;
 
 import android.util.SparseArray;
 
+import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -94,6 +95,10 @@ public final class CollectionUtils {
         return new CopyOnWriteArrayList<E>(array);
     }
 
+    public static <E> ArrayDeque<E> newArrayDeque() {
+        return new ArrayDeque<E>();
+    }
+
     public static <E> SparseArray<E> newSparseArray() {
         return new SparseArray<E>();
     }
diff --git a/java/src/com/android/inputmethod/latin/utils/StringUtils.java b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
index 20cc5d815..be4184093 100644
--- a/java/src/com/android/inputmethod/latin/utils/StringUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/StringUtils.java
@@ -370,12 +370,19 @@ public final class StringUtils {
         return sb.toString();
     }
 
+    /**
+     * Convert hex string to byte array. The string length must be an even number.
+     */
     @UsedForTesting
     public static byte[] hexStringToByteArray(String hexString) {
         if (TextUtils.isEmpty(hexString)) {
             return null;
         }
         final int N = hexString.length();
+        if (N % 2 != 0) {
+            throw new NumberFormatException("Input hex string length must be an even number."
+                    + " Length = " + N);
+        }
         final byte[] bytes = new byte[N / 2];
         for (int i = 0; i < N; i += 2) {
             bytes[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4)