diff --git a/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java b/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java
index ae826fe..063f211 100644
--- a/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java
+++ b/java/src/com/android/inputmethod/accessibility/AccessibilityEntityProvider.java
@@ -159,7 +159,7 @@
 
             // Add the virtual children of the root View.
             final Keyboard keyboard = mKeyboardView.getKeyboard();
-            for (final Key key : keyboard.getKeys()) {
+            for (final Key key : keyboard.getSortedKeys()) {
                 final int childVirtualViewId = generateVirtualViewIdForKey(key);
                 rootInfo.addChild(mKeyboardView, childVirtualViewId);
             }
@@ -307,7 +307,7 @@
         }
         mVirtualViewIdToKey.clear();
 
-        for (final Key key : keyboard.getKeys()) {
+        for (final Key key : keyboard.getSortedKeys()) {
             final int virtualViewId = generateVirtualViewIdForKey(key);
             mVirtualViewIdToKey.put(virtualViewId, key);
         }
diff --git a/java/src/com/android/inputmethod/keyboard/EmojiPalettesView.java b/java/src/com/android/inputmethod/keyboard/EmojiPalettesView.java
index 3c50401..d8b5758 100644
--- a/java/src/com/android/inputmethod/keyboard/EmojiPalettesView.java
+++ b/java/src/com/android/inputmethod/keyboard/EmojiPalettesView.java
@@ -298,7 +298,7 @@
 
         private int getCategoryPageCount(final int categoryId) {
             final Keyboard keyboard = mLayoutSet.getKeyboard(sCategoryElementId[categoryId]);
-            return (keyboard.getKeys().size() - 1) / mMaxPageKeyCount + 1;
+            return (keyboard.getSortedKeys().size() - 1) / mMaxPageKeyCount + 1;
         }
 
         // Returns a pair of the category id and the category page id from the view pager's page
@@ -347,7 +347,8 @@
                 }
 
                 final Keyboard keyboard = mLayoutSet.getKeyboard(sCategoryElementId[categoryId]);
-                final Key[][] sortedKeys = sortKeysIntoPages(keyboard.getKeys(), mMaxPageKeyCount);
+                final Key[][] sortedKeys = sortKeysIntoPages(
+                        keyboard.getSortedKeys(), mMaxPageKeyCount);
                 for (int pageId = 0; pageId < sortedKeys.length; ++pageId) {
                     final DynamicGridKeyboard tempKeyboard = new DynamicGridKeyboard(mPrefs,
                             mLayoutSet.getKeyboard(KeyboardId.ELEMENT_EMOJI_RECENTS),
diff --git a/java/src/com/android/inputmethod/keyboard/Keyboard.java b/java/src/com/android/inputmethod/keyboard/Keyboard.java
index 5162770..801e325 100644
--- a/java/src/com/android/inputmethod/keyboard/Keyboard.java
+++ b/java/src/com/android/inputmethod/keyboard/Keyboard.java
@@ -78,7 +78,7 @@
     public final int mMaxMoreKeysKeyboardColumn;
 
     /** List of keys in this keyboard */
-    private final List<Key> mKeys;
+    private final List<Key> mSortedKeys;
     public final List<Key> mShiftKeys;
     public final List<Key> mAltCodeKeysWhileTyping;
     public final KeyboardIconsSet mIconsSet;
@@ -103,14 +103,16 @@
         mTopPadding = params.mTopPadding;
         mVerticalGap = params.mVerticalGap;
 
-        mKeys = Collections.unmodifiableList(CollectionUtils.newArrayList(params.mKeys));
+        mSortedKeys = Collections.unmodifiableList(
+                CollectionUtils.newArrayList(params.mSortedKeys));
         mShiftKeys = Collections.unmodifiableList(params.mShiftKeys);
         mAltCodeKeysWhileTyping = Collections.unmodifiableList(params.mAltCodeKeysWhileTyping);
         mIconsSet = params.mIconsSet;
 
         mProximityInfo = new ProximityInfo(params.mId.mLocale.toString(),
                 params.GRID_WIDTH, params.GRID_HEIGHT, mOccupiedWidth, mOccupiedHeight,
-                mMostCommonKeyWidth, mMostCommonKeyHeight, mKeys, params.mTouchPositionCorrection);
+                mMostCommonKeyWidth, mMostCommonKeyHeight, mSortedKeys,
+                params.mTouchPositionCorrection);
         mProximityCharsCorrectionEnabled = params.mProximityCharsCorrectionEnabled;
     }
 
@@ -129,7 +131,7 @@
         mTopPadding = keyboard.mTopPadding;
         mVerticalGap = keyboard.mVerticalGap;
 
-        mKeys = keyboard.mKeys;
+        mSortedKeys = keyboard.mSortedKeys;
         mShiftKeys = keyboard.mShiftKeys;
         mAltCodeKeysWhileTyping = keyboard.mAltCodeKeysWhileTyping;
         mIconsSet = keyboard.mIconsSet;
@@ -154,12 +156,18 @@
         return mProximityInfo;
     }
 
-    public List<Key> getKeys() {
-        return mKeys;
+    /**
+     * Return the sorted list of keys of this keyboard.
+     * The keys are sorted from top-left to bottom-right order.
+     * The list may contain {@link Spacer} object as well.
+     * @return the sorted unmodifiable list of {@link Key}s of this keyboard.
+     */
+    public List<Key> getSortedKeys() {
+        return mSortedKeys;
     }
 
     public Key getKeyFromOutputText(final String outputText) {
-        for (final Key key : getKeys()) {
+        for (final Key key : getSortedKeys()) {
             if (outputText.equals(key.getOutputText())) {
                 return key;
             }
@@ -177,7 +185,7 @@
                 return mKeyCache.valueAt(index);
             }
 
-            for (final Key key : getKeys()) {
+            for (final Key key : getSortedKeys()) {
                 if (key.getCode() == code) {
                     mKeyCache.put(code, key);
                     return key;
@@ -193,7 +201,7 @@
             return true;
         }
 
-        for (final Key key : getKeys()) {
+        for (final Key key : getSortedKeys()) {
             if (key == aKey) {
                 mKeyCache.put(key.getCode(), key);
                 return true;
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardView.java b/java/src/com/android/inputmethod/keyboard/KeyboardView.java
index 18e51d3..8ca00b0 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardView.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardView.java
@@ -289,7 +289,7 @@
         // TODO: Confirm if it's really required to draw all keys when hardware acceleration is on.
         if (drawAllKeys || isHardwareAccelerated) {
             // Draw all keys.
-            for (final Key key : mKeyboard.getKeys()) {
+            for (final Key key : mKeyboard.getSortedKeys()) {
                 onDrawKey(key, canvas, paint);
             }
         } else {
diff --git a/java/src/com/android/inputmethod/keyboard/MoreKeysDetector.java b/java/src/com/android/inputmethod/keyboard/MoreKeysDetector.java
index abff202..5a9d475 100644
--- a/java/src/com/android/inputmethod/keyboard/MoreKeysDetector.java
+++ b/java/src/com/android/inputmethod/keyboard/MoreKeysDetector.java
@@ -43,7 +43,7 @@
 
         Key nearestKey = null;
         int nearestDist = (y < 0) ? mSlideAllowanceSquareTop : mSlideAllowanceSquare;
-        for (final Key key : keyboard.getKeys()) {
+        for (final Key key : keyboard.getSortedKeys()) {
             final int dist = key.squaredDistanceToEdge(touchX, touchY);
             if (dist < nearestDist) {
                 nearestKey = key;
diff --git a/java/src/com/android/inputmethod/keyboard/ProximityInfo.java b/java/src/com/android/inputmethod/keyboard/ProximityInfo.java
index fdb20f8..3746d5b 100644
--- a/java/src/com/android/inputmethod/keyboard/ProximityInfo.java
+++ b/java/src/com/android/inputmethod/keyboard/ProximityInfo.java
@@ -51,13 +51,13 @@
     private final int mKeyboardHeight;
     private final int mMostCommonKeyWidth;
     private final int mMostCommonKeyHeight;
-    private final List<Key> mKeys;
+    private final List<Key> mSortedKeys;
     private final List<Key>[] mGridNeighbors;
     private final String mLocaleStr;
 
     ProximityInfo(final String localeStr, final int gridWidth, final int gridHeight,
             final int minWidth, final int height, final int mostCommonKeyWidth,
-            final int mostCommonKeyHeight, final List<Key> keys,
+            final int mostCommonKeyHeight, final List<Key> sortedKeys,
             final TouchPositionCorrection touchPositionCorrection) {
         if (TextUtils.isEmpty(localeStr)) {
             mLocaleStr = "";
@@ -73,7 +73,7 @@
         mKeyboardHeight = height;
         mMostCommonKeyHeight = mostCommonKeyHeight;
         mMostCommonKeyWidth = mostCommonKeyWidth;
-        mKeys = keys;
+        mSortedKeys = sortedKeys;
         mGridNeighbors = new List[mGridSize];
         if (minWidth == 0 || height == 0) {
             // No proximity required. Keyboard might be more keys keyboard.
@@ -146,8 +146,8 @@
             }
         }
 
-        final List<Key> keys = mKeys;
-        final int keyCount = getProximityInfoKeysCount(keys);
+        final List<Key> sortedKeys = mSortedKeys;
+        final int keyCount = getProximityInfoKeysCount(sortedKeys);
         final int[] keyXCoordinates = new int[keyCount];
         final int[] keyYCoordinates = new int[keyCount];
         final int[] keyWidths = new int[keyCount];
@@ -157,8 +157,8 @@
         final float[] sweetSpotCenterYs;
         final float[] sweetSpotRadii;
 
-        for (int infoIndex = 0, keyIndex = 0; keyIndex < keys.size(); keyIndex++) {
-            final Key key = keys.get(keyIndex);
+        for (int infoIndex = 0, keyIndex = 0; keyIndex < sortedKeys.size(); keyIndex++) {
+            final Key key = sortedKeys.get(keyIndex);
             // Excluding from key coordinate arrays
             if (!needsProximityInfo(key)) {
                 continue;
@@ -181,8 +181,8 @@
             final int rows = touchPositionCorrection.getRows();
             final float defaultRadius = DEFAULT_TOUCH_POSITION_CORRECTION_RADIUS
                     * (float)Math.hypot(mMostCommonKeyWidth, mMostCommonKeyHeight);
-            for (int infoIndex = 0, keyIndex = 0; keyIndex < keys.size(); keyIndex++) {
-                final Key key = keys.get(keyIndex);
+            for (int infoIndex = 0, keyIndex = 0; keyIndex < sortedKeys.size(); keyIndex++) {
+                final Key key = sortedKeys.get(keyIndex);
                 // Excluding from touch position correction arrays
                 if (!needsProximityInfo(key)) {
                     continue;
@@ -244,7 +244,7 @@
 
     private void computeNearestNeighbors() {
         final int defaultWidth = mMostCommonKeyWidth;
-        final int keyCount = mKeys.size();
+        final int keyCount = mSortedKeys.size();
         final int gridSize = mGridNeighbors.length;
         final int threshold = (int) (defaultWidth * SEARCH_DISTANCE);
         final int thresholdSquared = threshold * threshold;
@@ -263,7 +263,7 @@
         final int[] neighborCountPerCell = new int[gridSize];
         final int halfCellWidth = mCellWidth / 2;
         final int halfCellHeight = mCellHeight / 2;
-        for (final Key key : mKeys) {
+        for (final Key key : mSortedKeys) {
             if (key.isSpacer()) continue;
 
 /* HOW WE PRE-SELECT THE CELLS (iterate over only the relevant cells, instead of all of them)
diff --git a/java/src/com/android/inputmethod/keyboard/internal/DynamicGridKeyboard.java b/java/src/com/android/inputmethod/keyboard/internal/DynamicGridKeyboard.java
index dd5ec1d..bf76ca4 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/DynamicGridKeyboard.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/DynamicGridKeyboard.java
@@ -68,7 +68,7 @@
     }
 
     private Key getTemplateKey(final int code) {
-        for (final Key key : super.getKeys()) {
+        for (final Key key : super.getSortedKeys()) {
             if (key.getCode() == code) {
                 return key;
             }
@@ -207,7 +207,7 @@
     }
 
     @Override
-    public List<Key> getKeys() {
+    public List<Key> getSortedKeys() {
         synchronized (mLock) {
             if (mCachedGridKeys != null) {
                 return mCachedGridKeys;
@@ -222,7 +222,7 @@
     @Override
     public List<Key> getNearestKeys(final int x, final int y) {
         // TODO: Calculate the nearest key index in mGridKeys from x and y.
-        return getKeys();
+        return getSortedKeys();
     }
 
     static final class GridKey extends Key {
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java b/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java
index 153391e..a61a79b 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyboardParams.java
@@ -24,6 +24,8 @@
 import com.android.inputmethod.latin.utils.CollectionUtils;
 
 import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.SortedSet;
 import java.util.TreeSet;
 
 public class KeyboardParams {
@@ -58,7 +60,8 @@
     public int GRID_WIDTH;
     public int GRID_HEIGHT;
 
-    public final TreeSet<Key> mKeys = CollectionUtils.newTreeSet(); // ordered set
+    // Keys are sorted from top-left to bottom-right order.
+    public final SortedSet<Key> mSortedKeys = new TreeSet<Key>(ROW_COLUMN_COMPARATOR);
     public final ArrayList<Key> mShiftKeys = CollectionUtils.newArrayList();
     public final ArrayList<Key> mAltCodeKeysWhileTyping = CollectionUtils.newArrayList();
     public final KeyboardIconsSet mIconsSet = new KeyboardIconsSet();
@@ -75,8 +78,20 @@
     public final TouchPositionCorrection mTouchPositionCorrection =
             new TouchPositionCorrection();
 
+    // Comparator to sort {@link Key}s from top-left to bottom-right order.
+    private static final Comparator<Key> ROW_COLUMN_COMPARATOR = new Comparator<Key>() {
+        @Override
+        public int compare(final Key lhs, final Key rhs) {
+            if (lhs.getY() < rhs.getY()) return -1;
+            if (lhs.getY() > rhs.getY()) return 1;
+            if (lhs.getX() < rhs.getX()) return -1;
+            if (lhs.getX() > rhs.getX()) return 1;
+            return 0;
+        }
+    };
+
     protected void clearKeys() {
-        mKeys.clear();
+        mSortedKeys.clear();
         mShiftKeys.clear();
         clearHistogram();
     }
@@ -88,7 +103,7 @@
             // Ignore zero width {@link Spacer}.
             return;
         }
-        mKeys.add(key);
+        mSortedKeys.add(key);
         if (isSpacer) {
             return;
         }
diff --git a/java/src/com/android/inputmethod/research/ResearchLogger.java b/java/src/com/android/inputmethod/research/ResearchLogger.java
index b1f54c0..d907dd1 100644
--- a/java/src/com/android/inputmethod/research/ResearchLogger.java
+++ b/java/src/com/android/inputmethod/research/ResearchLogger.java
@@ -1362,7 +1362,7 @@
                 kid.navigateNext(), kid.navigatePrevious(), kid.mClobberSettingsKey,
                 isPasswordView, kid.mSupportsSwitchingToShortcutIme, kid.mHasShortcutKey,
                 kid.mLanguageSwitchKeyEnabled, kid.isMultiLine(), keyboard.mOccupiedWidth,
-                keyboard.mOccupiedHeight, keyboard.getKeys());
+                keyboard.mOccupiedHeight, keyboard.getSortedKeys());
     }
 
     /**
diff --git a/tests/src/com/android/inputmethod/keyboard/layout/expected/ActualKeyboardBuilder.java b/tests/src/com/android/inputmethod/keyboard/layout/expected/ActualKeyboardBuilder.java
index b0cd4df..26d2e2a 100644
--- a/tests/src/com/android/inputmethod/keyboard/layout/expected/ActualKeyboardBuilder.java
+++ b/tests/src/com/android/inputmethod/keyboard/layout/expected/ActualKeyboardBuilder.java
@@ -24,27 +24,13 @@
 import com.android.inputmethod.latin.utils.StringUtils;
 
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.List;
 
 /**
  * This class builds an actual keyboard for unit test.
  */
 public final class ActualKeyboardBuilder extends AbstractKeyboardBuilder<Key> {
-    // Comparator to sort {@link Key}s from top-left to bottom-right order.
-    private static final Comparator<Key> ROW_COLUMN_COMPARATOR = new Comparator<Key>() {
-        @Override
-        public int compare(final Key lhs, final Key rhs) {
-            if (lhs.getY() < rhs.getY()) return -1;
-            if (lhs.getY() > rhs.getY()) return 1;
-            if (lhs.getX() < rhs.getX()) return -1;
-            if (lhs.getX() > rhs.getX()) return 1;
-            return 0;
-        }
-    };
-
-    private static ArrayList<Key> filterOutSpacerAndSortKeys(final List<Key> keys) {
+    private static ArrayList<Key> filterOutSpacer(final List<Key> keys) {
         final ArrayList<Key> filteredKeys = CollectionUtils.newArrayList();
         for (final Key key : keys) {
             if (key.isSpacer()) {
@@ -52,25 +38,23 @@
             }
             filteredKeys.add(key);
         }
-        Collections.sort(filteredKeys, ROW_COLUMN_COMPARATOR);
         return filteredKeys;
     }
 
     /**
      * Create the keyboard that consists of the array of rows of the actual keyboard's keys.
-     * @param keys the list of keys of the actual keyboard.
+     * @param sortedKeys the sorted list of keys of the actual keyboard.
      * @return the actual keyboard grouped with rows.
      */
-    public static Key[][] buildKeyboard(final List<Key> keys) {
-        // Filter out spacer and sort keys from top-left to bottom-right order to prepare to
-        // create rows.
-        final ArrayList<Key> sortedKeys = filterOutSpacerAndSortKeys(keys);
+    public static Key[][] buildKeyboard(final List<Key> sortedKeys) {
+        // Filter out spacer to prepare to create rows.
+        final ArrayList<Key> filteredSortedKeys = filterOutSpacer(sortedKeys);
 
         // Grouping keys into rows.
         final ArrayList<ArrayList<Key>> rows = CollectionUtils.newArrayList();
         ArrayList<Key> elements = CollectionUtils.newArrayList();
-        int lastY = sortedKeys.get(0).getY();
-        for (final Key key : sortedKeys) {
+        int lastY = filteredSortedKeys.get(0).getY();
+        for (final Key key : filteredSortedKeys) {
             if (lastY != key.getY()) {
                 // A new row is starting.
                 lastY = key.getY();
diff --git a/tests/src/com/android/inputmethod/keyboard/layout/tests/LayoutTestsBase.java b/tests/src/com/android/inputmethod/keyboard/layout/tests/LayoutTestsBase.java
index 555ec89..4002c49 100644
--- a/tests/src/com/android/inputmethod/keyboard/layout/tests/LayoutTestsBase.java
+++ b/tests/src/com/android/inputmethod/keyboard/layout/tests/LayoutTestsBase.java
@@ -150,7 +150,8 @@
         // Create actual keyboard object.
         final Keyboard keyboard = mKeyboardLayoutSet.getKeyboard(elementId);
         // Create actual keyboard to be compared with the expected keyboard.
-        final Key[][] actualKeyboard = ActualKeyboardBuilder.buildKeyboard(keyboard.getKeys());
+        final Key[][] actualKeyboard = ActualKeyboardBuilder.buildKeyboard(
+                keyboard.getSortedKeys());
 
         // Dump human readable definition of expected/actual keyboards.
         Log.d(tag, "expected=\n" + ExpectedKeyboardBuilder.toString(expectedKeyboard));