Move some methods out from SubtypeSwitcher

Change-Id: I89aaf87d7d0cc204b0ca0f61c2f64d15e2df848e

6 files changed, 168 insertions, 122 deletions

diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index dc665471d..eb0037e8c 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -626,7 +626,7 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
     private void refreshPersonalizationDictionarySession(
             final SettingsValues currentSettingsValues) {
         mDictionaryFacilitator.setIsMonolingualUser(
-                mSubtypeSwitcher.isSystemLocaleSameAsLocaleOfAllEnabledSubtypesOfEnabledImes());
+                mRichImm.isSystemLocaleSameAsLocaleOfAllEnabledSubtypesOfEnabledImes());
         mPersonalizationDictionaryUpdater.onLoadSettings(
                 currentSettingsValues.mUsePersonalizedDicts);
         mContextualDictionaryUpdater.onLoadSettings(currentSettingsValues.mUsePersonalizedDicts);
@@ -863,7 +863,7 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
         // also wouldn't be consuming gesture data.
         mGestureConsumer = GestureConsumer.NULL_GESTURE_CONSUMER;
         mRichImm.clearSubtypeCaches();
-        mSubtypeSwitcher.refreshSubtypeInfo();
+        mSubtypeSwitcher.onSubtypeChanged(mRichImm.getCurrentRawSubtype());
         final KeyboardSwitcher switcher = mKeyboardSwitcher;
         switcher.updateKeyboardTheme();
         final MainKeyboardView mainKeyboardView = switcher.getMainKeyboardView();
diff --git a/java/src/com/android/inputmethod/latin/RichInputMethodManager.java b/java/src/com/android/inputmethod/latin/RichInputMethodManager.java
index 8d8e7ac38..a53837a59 100644
--- a/java/src/com/android/inputmethod/latin/RichInputMethodManager.java
+++ b/java/src/com/android/inputmethod/latin/RichInputMethodManager.java
@@ -29,6 +29,8 @@ import android.view.inputmethod.InputMethodManager;
 import android.view.inputmethod.InputMethodSubtype;
 
 import com.android.inputmethod.compat.InputMethodManagerCompatWrapper;
+import com.android.inputmethod.compat.InputMethodSubtypeCompatUtils;
+import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.settings.AdditionalFeaturesSettingUtils;
 import com.android.inputmethod.latin.settings.Settings;
 import com.android.inputmethod.latin.utils.AdditionalSubtypeUtils;
@@ -36,7 +38,10 @@ import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
 
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
+import java.util.Set;
 
 import javax.annotation.Nonnull;
 
@@ -432,4 +437,29 @@ public class RichInputMethodManager {
         }
         return mImmWrapper.shouldOfferSwitchingToNextInputMethod(binder);
     }
+
+    public boolean isSystemLocaleSameAsLocaleOfAllEnabledSubtypesOfEnabledImes() {
+        final Locale systemLocale = mContext.getResources().getConfiguration().locale;
+        final Set<InputMethodSubtype> enabledSubtypesOfEnabledImes = new HashSet<>();
+        final InputMethodManager inputMethodManager = getInputMethodManager();
+        final List<InputMethodInfo> enabledInputMethodInfoList =
+                inputMethodManager.getEnabledInputMethodList();
+        for (final InputMethodInfo info : enabledInputMethodInfoList) {
+            final List<InputMethodSubtype> enabledSubtypes =
+                    inputMethodManager.getEnabledInputMethodSubtypeList(
+                            info, true /* allowsImplicitlySelectedSubtypes */);
+            if (enabledSubtypes.isEmpty()) {
+                // An IME with no subtypes is found.
+                return false;
+            }
+            enabledSubtypesOfEnabledImes.addAll(enabledSubtypes);
+        }
+        for (final InputMethodSubtype subtype : enabledSubtypesOfEnabledImes) {
+            if (!subtype.isAuxiliary() && !subtype.getLocale().isEmpty()
+                    && !systemLocale.equals(SubtypeLocaleUtils.getSubtypeLocale(subtype))) {
+                return false;
+            }
+        }
+        return true;
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java b/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java
index 8d055531c..1a6c6ba06 100644
--- a/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java
+++ b/java/src/com/android/inputmethod/latin/RichInputMethodSubtype.java
@@ -16,33 +16,45 @@
 
 package com.android.inputmethod.latin;
 
+import static com.android.inputmethod.latin.common.Constants.Subtype.KEYBOARD_MODE;
+
+import android.util.Log;
 import android.view.inputmethod.InputMethodSubtype;
 
+import com.android.inputmethod.compat.InputMethodSubtypeCompatUtils;
+import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.utils.LocaleUtils;
 import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
 
 import java.util.Arrays;
 import java.util.Locale;
 
+import javax.annotation.Nonnull;
+
 /**
  * Enrichment class for InputMethodSubtype to enable concurrent multi-lingual input.
  *
  * Right now, this returns the extra value of its primary subtype.
  */
 public final class RichInputMethodSubtype {
+    private static final String TAG = RichInputMethodSubtype.class.getSimpleName();
+
+    @Nonnull
     private final InputMethodSubtype mSubtype;
+    @Nonnull
     private final Locale[] mLocales;
 
-    public RichInputMethodSubtype(final InputMethodSubtype subtype, final Locale... locales) {
+    public RichInputMethodSubtype(@Nonnull final InputMethodSubtype subtype,
+            @Nonnull final Locale... locales) {
         mSubtype = subtype;
-        mLocales = new Locale[locales.length+1];
+        mLocales = new Locale[locales.length + 1];
         mLocales[0] = LocaleUtils.constructLocaleFromString(mSubtype.getLocale());
         System.arraycopy(locales, 0, mLocales, 1, locales.length);
     }
 
     // Extra values are determined by the primary subtype. This is probably right, but
     // we may have to revisit this later.
-    public String getExtraValueOf(final String key) {
+    public String getExtraValueOf(@Nonnull final String key) {
         return mSubtype.getExtraValueOf(key);
     }
 
@@ -80,6 +92,7 @@ public final class RichInputMethodSubtype {
     //  en_US azerty  T  English   English (US)
     //  zz    azerty  T  AZERTY    AZERTY
     // Get the RichInputMethodSubtype's full display name in its locale.
+    @Nonnull
     public String getFullDisplayName() {
         if (isNoLanguage()) {
             return SubtypeLocaleUtils.getKeyboardLayoutSetDisplayName(mSubtype);
@@ -88,6 +101,7 @@ public final class RichInputMethodSubtype {
     }
 
     // Get the RichInputMethodSubtype's middle display name in its locale.
+    @Nonnull
     public String getMiddleDisplayName() {
         if (isNoLanguage()) {
             return SubtypeLocaleUtils.getKeyboardLayoutSetDisplayName(mSubtype);
@@ -96,7 +110,7 @@ public final class RichInputMethodSubtype {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(final Object o) {
         if (!(o instanceof RichInputMethodSubtype)) {
             return false;
         }
@@ -114,6 +128,7 @@ public final class RichInputMethodSubtype {
         return "Multi-lingual subtype: " + mSubtype.toString() + ", " + Arrays.toString(mLocales);
     }
 
+    @Nonnull
     public Locale[] getLocales() {
         return mLocales;
     }
@@ -124,5 +139,80 @@ public final class RichInputMethodSubtype {
     }
 
     // TODO: remove this method
+    @Nonnull
     public InputMethodSubtype getRawSubtype() { return mSubtype; }
+
+    // Dummy no language QWERTY subtype. See {@link R.xml.method}.
+    private static final int SUBTYPE_ID_OF_DUMMY_NO_LANGUAGE_SUBTYPE = 0xdde0bfd3;
+    private static final String EXTRA_VALUE_OF_DUMMY_NO_LANGUAGE_SUBTYPE =
+            "KeyboardLayoutSet=" + SubtypeLocaleUtils.QWERTY
+            + "," + Constants.Subtype.ExtraValue.ASCII_CAPABLE
+            + "," + Constants.Subtype.ExtraValue.ENABLED_WHEN_DEFAULT_IS_NOT_ASCII_CAPABLE
+            + "," + Constants.Subtype.ExtraValue.EMOJI_CAPABLE;
+    @Nonnull
+    private static final RichInputMethodSubtype DUMMY_NO_LANGUAGE_SUBTYPE =
+            new RichInputMethodSubtype(InputMethodSubtypeCompatUtils.newInputMethodSubtype(
+                    R.string.subtype_no_language_qwerty, R.drawable.ic_ime_switcher_dark,
+                    SubtypeLocaleUtils.NO_LANGUAGE, KEYBOARD_MODE,
+                    EXTRA_VALUE_OF_DUMMY_NO_LANGUAGE_SUBTYPE,
+                    false /* isAuxiliary */, false /* overridesImplicitlyEnabledSubtype */,
+                    SUBTYPE_ID_OF_DUMMY_NO_LANGUAGE_SUBTYPE));
+    // Caveat: We probably should remove this when we add an Emoji subtype in {@link R.xml.method}.
+    // Dummy Emoji subtype. See {@link R.xml.method}.
+    private static final int SUBTYPE_ID_OF_DUMMY_EMOJI_SUBTYPE = 0xd78b2ed0;
+    private static final String EXTRA_VALUE_OF_DUMMY_EMOJI_SUBTYPE =
+            "KeyboardLayoutSet=" + SubtypeLocaleUtils.EMOJI
+            + "," + Constants.Subtype.ExtraValue.EMOJI_CAPABLE;
+    @Nonnull
+    private static final RichInputMethodSubtype DUMMY_EMOJI_SUBTYPE = new RichInputMethodSubtype(
+            InputMethodSubtypeCompatUtils.newInputMethodSubtype(
+                    R.string.subtype_emoji, R.drawable.ic_ime_switcher_dark,
+                    SubtypeLocaleUtils.NO_LANGUAGE, KEYBOARD_MODE,
+                    EXTRA_VALUE_OF_DUMMY_EMOJI_SUBTYPE,
+                    false /* isAuxiliary */, false /* overridesImplicitlyEnabledSubtype */,
+                    SUBTYPE_ID_OF_DUMMY_EMOJI_SUBTYPE));
+    private static RichInputMethodSubtype sNoLanguageSubtype;
+    private static RichInputMethodSubtype sEmojiSubtype;
+
+    @Nonnull
+    public static RichInputMethodSubtype getNoLanguageSubtype() {
+        RichInputMethodSubtype noLanguageSubtype = sNoLanguageSubtype;
+        if (noLanguageSubtype == null) {
+            final InputMethodSubtype rawNoLanguageSubtype = RichInputMethodManager.getInstance()
+                    .findSubtypeByLocaleAndKeyboardLayoutSet(
+                            SubtypeLocaleUtils.NO_LANGUAGE, SubtypeLocaleUtils.QWERTY);
+            if (rawNoLanguageSubtype != null) {
+                noLanguageSubtype = new RichInputMethodSubtype(rawNoLanguageSubtype);
+            }
+        }
+        if (noLanguageSubtype != null) {
+            sNoLanguageSubtype = noLanguageSubtype;
+            return noLanguageSubtype;
+        }
+        Log.w(TAG, "Can't find any language with QWERTY subtype");
+        Log.w(TAG, "No input method subtype found; returning dummy subtype: "
+                + DUMMY_NO_LANGUAGE_SUBTYPE);
+        return DUMMY_NO_LANGUAGE_SUBTYPE;
+    }
+
+    @Nonnull
+    public static RichInputMethodSubtype getEmojiSubtype() {
+        RichInputMethodSubtype emojiSubtype = sEmojiSubtype;
+        if (emojiSubtype == null) {
+            final InputMethodSubtype rawEmojiSubtype = RichInputMethodManager.getInstance()
+                    .findSubtypeByLocaleAndKeyboardLayoutSet(
+                            SubtypeLocaleUtils.NO_LANGUAGE, SubtypeLocaleUtils.EMOJI);
+            if (rawEmojiSubtype != null) {
+                emojiSubtype = new RichInputMethodSubtype(rawEmojiSubtype);
+            }
+        }
+        if (emojiSubtype != null) {
+            sEmojiSubtype = emojiSubtype;
+            return emojiSubtype;
+        }
+        Log.w(TAG, "Can't find emoji subtype");
+        Log.w(TAG, "No input method subtype found; returning dummy subtype: "
+                + DUMMY_EMOJI_SUBTYPE);
+        return DUMMY_EMOJI_SUBTYPE;
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/SubtypeSwitcher.java b/java/src/com/android/inputmethod/latin/SubtypeSwitcher.java
index 98bce95bd..306ccf0d0 100644
--- a/java/src/com/android/inputmethod/latin/SubtypeSwitcher.java
+++ b/java/src/com/android/inputmethod/latin/SubtypeSwitcher.java
@@ -17,6 +17,7 @@
 package com.android.inputmethod.latin;
 
 import static com.android.inputmethod.latin.common.Constants.Subtype.ExtraValue.REQ_NETWORK_CONNECTIVITY;
+
 import android.content.Context;
 import android.content.Intent;
 import android.content.res.Resources;
@@ -31,18 +32,14 @@ import android.view.inputmethod.InputMethodManager;
 import android.view.inputmethod.InputMethodSubtype;
 
 import com.android.inputmethod.annotations.UsedForTesting;
-import com.android.inputmethod.compat.InputMethodSubtypeCompatUtils;
 import com.android.inputmethod.keyboard.KeyboardSwitcher;
 import com.android.inputmethod.keyboard.internal.LanguageOnSpacebarHelper;
-import com.android.inputmethod.latin.common.Constants;
 import com.android.inputmethod.latin.define.DebugFlags;
 import com.android.inputmethod.latin.utils.SubtypeLocaleUtils;
 
-import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Set;
 
 import javax.annotation.Nonnull;
 
@@ -60,39 +57,8 @@ public final class SubtypeSwitcher {
     private InputMethodInfo mShortcutInputMethodInfo;
     private InputMethodSubtype mShortcutSubtype;
     private RichInputMethodSubtype mCurrentRichInputMethodSubtype;
-    private RichInputMethodSubtype mNoLanguageSubtype;
-    private RichInputMethodSubtype mEmojiSubtype;
     private boolean mIsNetworkConnected;
 
-    private static final String KEYBOARD_MODE = "keyboard";
-    // Dummy no language QWERTY subtype. See {@link R.xml.method}.
-    private static final int SUBTYPE_ID_OF_DUMMY_NO_LANGUAGE_SUBTYPE = 0xdde0bfd3;
-    private static final String EXTRA_VALUE_OF_DUMMY_NO_LANGUAGE_SUBTYPE =
-            "KeyboardLayoutSet=" + SubtypeLocaleUtils.QWERTY
-            + "," + Constants.Subtype.ExtraValue.ASCII_CAPABLE
-            + "," + Constants.Subtype.ExtraValue.ENABLED_WHEN_DEFAULT_IS_NOT_ASCII_CAPABLE
-            + "," + Constants.Subtype.ExtraValue.EMOJI_CAPABLE;
-    private static final RichInputMethodSubtype DUMMY_NO_LANGUAGE_SUBTYPE =
-            new RichInputMethodSubtype(InputMethodSubtypeCompatUtils.newInputMethodSubtype(
-                    R.string.subtype_no_language_qwerty, R.drawable.ic_ime_switcher_dark,
-                    SubtypeLocaleUtils.NO_LANGUAGE, KEYBOARD_MODE,
-                    EXTRA_VALUE_OF_DUMMY_NO_LANGUAGE_SUBTYPE,
-                    false /* isAuxiliary */, false /* overridesImplicitlyEnabledSubtype */,
-                    SUBTYPE_ID_OF_DUMMY_NO_LANGUAGE_SUBTYPE));
-    // Caveat: We probably should remove this when we add an Emoji subtype in {@link R.xml.method}.
-    // Dummy Emoji subtype. See {@link R.xml.method}.
-    private static final int SUBTYPE_ID_OF_DUMMY_EMOJI_SUBTYPE = 0xd78b2ed0;
-    private static final String EXTRA_VALUE_OF_DUMMY_EMOJI_SUBTYPE =
-            "KeyboardLayoutSet=" + SubtypeLocaleUtils.EMOJI
-            + "," + Constants.Subtype.ExtraValue.EMOJI_CAPABLE;
-    private static final RichInputMethodSubtype DUMMY_EMOJI_SUBTYPE = new RichInputMethodSubtype(
-            InputMethodSubtypeCompatUtils.newInputMethodSubtype(
-                    R.string.subtype_emoji, R.drawable.ic_ime_switcher_dark,
-                    SubtypeLocaleUtils.NO_LANGUAGE, KEYBOARD_MODE,
-                    EXTRA_VALUE_OF_DUMMY_EMOJI_SUBTYPE,
-                    false /* isAuxiliary */, false /* overridesImplicitlyEnabledSubtype */,
-                    SUBTYPE_ID_OF_DUMMY_EMOJI_SUBTYPE));
-
     public static SubtypeSwitcher getInstance() {
         return sInstance;
     }
@@ -119,12 +85,8 @@ public final class SubtypeSwitcher {
         final NetworkInfo info = connectivityManager.getActiveNetworkInfo();
         mIsNetworkConnected = (info != null && info.isConnected());
 
-        refreshSubtypeInfo();
-        updateParametersOnStartInputView();
-    }
-
-    public void refreshSubtypeInfo() {
         onSubtypeChanged(mRichImm.getCurrentRawSubtype());
+        updateParametersOnStartInputView();
     }
 
     /**
@@ -267,31 +229,6 @@ public final class SubtypeSwitcher {
         return mLanguageOnSpacebarHelper.getLanguageOnSpacebarFormatType(subtype);
     }
 
-    public boolean isSystemLocaleSameAsLocaleOfAllEnabledSubtypesOfEnabledImes() {
-        final Locale systemLocale = mResources.getConfiguration().locale;
-        final Set<InputMethodSubtype> enabledSubtypesOfEnabledImes = new HashSet<>();
-        final InputMethodManager inputMethodManager = mRichImm.getInputMethodManager();
-        final List<InputMethodInfo> enabledInputMethodInfoList =
-                inputMethodManager.getEnabledInputMethodList();
-        for (final InputMethodInfo info : enabledInputMethodInfoList) {
-            final List<InputMethodSubtype> enabledSubtypes =
-                    inputMethodManager.getEnabledInputMethodSubtypeList(
-                            info, true /* allowsImplicitlySelectedSubtypes */);
-            if (enabledSubtypes.isEmpty()) {
-                // An IME with no subtypes is found.
-                return false;
-            }
-            enabledSubtypesOfEnabledImes.addAll(enabledSubtypes);
-        }
-        for (final InputMethodSubtype subtype : enabledSubtypesOfEnabledImes) {
-            if (!subtype.isAuxiliary() && !subtype.getLocale().isEmpty()
-                    && !systemLocale.equals(SubtypeLocaleUtils.getSubtypeLocale(subtype))) {
-                return false;
-            }
-        }
-        return true;
-    }
-
     private static RichInputMethodSubtype sForcedSubtypeForTesting = null;
 
     @UsedForTesting
@@ -313,39 +250,6 @@ public final class SubtypeSwitcher {
         return mCurrentRichInputMethodSubtype;
     }
 
-    public RichInputMethodSubtype getNoLanguageSubtype() {
-        if (mNoLanguageSubtype == null) {
-            mNoLanguageSubtype = new RichInputMethodSubtype(
-                    mRichImm.findSubtypeByLocaleAndKeyboardLayoutSet(
-                            SubtypeLocaleUtils.NO_LANGUAGE, SubtypeLocaleUtils.QWERTY));
-        }
-        if (mNoLanguageSubtype != null) {
-            return mNoLanguageSubtype;
-        }
-        Log.w(TAG, "Can't find any language with QWERTY subtype");
-        Log.w(TAG, "No input method subtype found; returning dummy subtype: "
-                + DUMMY_NO_LANGUAGE_SUBTYPE);
-        return DUMMY_NO_LANGUAGE_SUBTYPE;
-    }
-
-    public RichInputMethodSubtype getEmojiSubtype() {
-        if (mEmojiSubtype == null) {
-            final InputMethodSubtype rawEmojiSubtype =
-                    mRichImm.findSubtypeByLocaleAndKeyboardLayoutSet(
-                        SubtypeLocaleUtils.NO_LANGUAGE, SubtypeLocaleUtils.EMOJI);
-            if (null != rawEmojiSubtype) {
-                mEmojiSubtype = new RichInputMethodSubtype(rawEmojiSubtype);
-            }
-        }
-        if (mEmojiSubtype != null) {
-            return mEmojiSubtype;
-        }
-        Log.w(TAG, "Can't find emoji subtype");
-        Log.w(TAG, "No input method subtype found; returning dummy subtype: "
-                + DUMMY_EMOJI_SUBTYPE);
-        return DUMMY_EMOJI_SUBTYPE;
-    }
-
     public String getCombiningRulesExtraValueOfCurrentSubtype() {
         return SubtypeLocaleUtils.getCombiningRulesExtraValue(getCurrentSubtype().getRawSubtype());
     }
diff --git a/java/src/com/android/inputmethod/latin/utils/LocaleUtils.java b/java/src/com/android/inputmethod/latin/utils/LocaleUtils.java
index c519a0de6..4bab497ba 100644
--- a/java/src/com/android/inputmethod/latin/utils/LocaleUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/LocaleUtils.java
@@ -21,6 +21,8 @@ import android.text.TextUtils;
 import java.util.HashMap;
 import java.util.Locale;
 
+import javax.annotation.Nullable;
+
 /**
  * A class to help with handling Locales in string form.
  *
@@ -164,8 +166,10 @@ public final class LocaleUtils {
     /**
      * Creates a locale from a string specification.
      */
-    public static Locale constructLocaleFromString(final String localeStr) {
+    @Nullable
+    public static Locale constructLocaleFromString(@Nullable final String localeStr) {
         if (localeStr == null) {
+            // TODO: Should this be Locale.ROOT?
             return null;
         }
         synchronized (sLocaleCache) {
@@ -173,7 +177,7 @@ public final class LocaleUtils {
             if (retval != null) {
                 return retval;
             }
-            String[] localeParams = localeStr.split("_", 3);
+            final String[] localeParams = localeStr.split("_", 3);
             if (localeParams.length == 1) {
                 retval = new Locale(localeParams[0]);
             } else if (localeParams.length == 2) {
@@ -184,6 +188,7 @@ public final class LocaleUtils {
             if (retval != null) {
                 sLocaleCache.put(localeStr, retval);
             }
+            // TODO: Should return Locale.ROOT instead of null?
             return retval;
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java b/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java
index 55c1dc9e5..e4a8ee2a6 100644
--- a/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java
+++ b/java/src/com/android/inputmethod/latin/utils/SubtypeLocaleUtils.java
@@ -34,6 +34,8 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Locale;
 
+import javax.annotation.Nonnull;
+
 /**
  * A helper class to deal with subtype locales.
   */
@@ -173,7 +175,8 @@ public final class SubtypeLocaleUtils {
         return nameId == null ? UNKNOWN_KEYBOARD_LAYOUT : nameId;
     }
 
-    public static Locale getDisplayLocaleOfSubtypeLocale(final String localeString) {
+    @Nonnull
+    public static Locale getDisplayLocaleOfSubtypeLocale(@Nonnull final String localeString) {
         if (NO_LANGUAGE.equals(localeString)) {
             return sResources.getConfiguration().locale;
         }
@@ -183,17 +186,20 @@ public final class SubtypeLocaleUtils {
         return LocaleUtils.constructLocaleFromString(localeString);
     }
 
-    public static String getSubtypeLocaleDisplayNameInSystemLocale(final String localeString) {
+    public static String getSubtypeLocaleDisplayNameInSystemLocale(
+            @Nonnull final String localeString) {
         final Locale displayLocale = sResources.getConfiguration().locale;
         return getSubtypeLocaleDisplayNameInternal(localeString, displayLocale);
     }
 
-    public static String getSubtypeLocaleDisplayName(final String localeString) {
+    @Nonnull
+    public static String getSubtypeLocaleDisplayName(@Nonnull final String localeString) {
         final Locale displayLocale = getDisplayLocaleOfSubtypeLocale(localeString);
         return getSubtypeLocaleDisplayNameInternal(localeString, displayLocale);
     }
 
-    public static String getSubtypeLanguageDisplayName(final String localeString) {
+    @Nonnull
+    public static String getSubtypeLanguageDisplayName(@Nonnull final String localeString) {
         final Locale displayLocale = getDisplayLocaleOfSubtypeLocale(localeString);
         final String languageString;
         if (sExceptionalLocaleDisplayedInRootLocale.containsKey(localeString)) {
@@ -205,8 +211,9 @@ public final class SubtypeLocaleUtils {
         return getSubtypeLocaleDisplayNameInternal(languageString, displayLocale);
     }
 
-    private static String getSubtypeLocaleDisplayNameInternal(final String localeString,
-            final Locale displayLocale) {
+    @Nonnull
+    private static String getSubtypeLocaleDisplayNameInternal(@Nonnull final String localeString,
+            @Nonnull final Locale displayLocale) {
         if (NO_LANGUAGE.equals(localeString)) {
             // No language subtype should be displayed in system locale.
             return sResources.getString(R.string.subtype_no_language);
@@ -255,8 +262,9 @@ public final class SubtypeLocaleUtils {
     //  en_US azerty  T  English (US) (AZERTY)   exception
     //  zz    azerty  T  Alphabet (AZERTY)       in system locale
 
-    private static String getReplacementString(final InputMethodSubtype subtype,
-            final Locale displayLocale) {
+    @Nonnull
+    private static String getReplacementString(@Nonnull final InputMethodSubtype subtype,
+            @Nonnull final Locale displayLocale) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN
                 && subtype.containsExtraValueKey(UNTRANSLATABLE_STRING_IN_SUBTYPE_NAME)) {
             return subtype.getExtraValueOf(UNTRANSLATABLE_STRING_IN_SUBTYPE_NAME);
@@ -264,20 +272,24 @@ public final class SubtypeLocaleUtils {
         return getSubtypeLocaleDisplayNameInternal(subtype.getLocale(), displayLocale);
     }
 
-    public static String getSubtypeDisplayNameInSystemLocale(final InputMethodSubtype subtype) {
+    @Nonnull
+    public static String getSubtypeDisplayNameInSystemLocale(
+            @Nonnull final InputMethodSubtype subtype) {
         final Locale displayLocale = sResources.getConfiguration().locale;
         return getSubtypeDisplayNameInternal(subtype, displayLocale);
     }
 
-    public static String getSubtypeNameForLogging(final InputMethodSubtype subtype) {
+    @Nonnull
+    public static String getSubtypeNameForLogging(@Nonnull final InputMethodSubtype subtype) {
         if (subtype == null) {
             return "<null subtype>";
         }
         return getSubtypeLocale(subtype) + "/" + getKeyboardLayoutSetName(subtype);
     }
 
-    private static String getSubtypeDisplayNameInternal(final InputMethodSubtype subtype,
-            final Locale displayLocale) {
+    @Nonnull
+    private static String getSubtypeDisplayNameInternal(@Nonnull final InputMethodSubtype subtype,
+            @Nonnull final Locale displayLocale) {
         final String replacementString = getReplacementString(subtype, displayLocale);
         // TODO: rework this for multi-lingual subtypes
         final int nameResId = subtype.getNameResId();
@@ -302,21 +314,26 @@ public final class SubtypeLocaleUtils {
                 getSubtypeName.runInLocale(sResources, displayLocale), displayLocale);
     }
 
-    public static Locale getSubtypeLocale(final InputMethodSubtype subtype) {
+    @Nonnull
+    public static Locale getSubtypeLocale(@Nonnull final InputMethodSubtype subtype) {
         final String localeString = subtype.getLocale();
         return LocaleUtils.constructLocaleFromString(localeString);
     }
 
-    public static String getKeyboardLayoutSetDisplayName(final InputMethodSubtype subtype) {
+    @Nonnull
+    public static String getKeyboardLayoutSetDisplayName(
+            @Nonnull final InputMethodSubtype subtype) {
         final String layoutName = getKeyboardLayoutSetName(subtype);
         return getKeyboardLayoutSetDisplayName(layoutName);
     }
 
-    public static String getKeyboardLayoutSetDisplayName(final String layoutName) {
+    @Nonnull
+    public static String getKeyboardLayoutSetDisplayName(@Nonnull final String layoutName) {
         return sKeyboardLayoutToDisplayNameMap.get(layoutName);
     }
 
-    public static String getKeyboardLayoutSetName(final RichInputMethodSubtype subtype) {
+    @Nonnull
+    public static String getKeyboardLayoutSetName(@Nonnull final RichInputMethodSubtype subtype) {
         return getKeyboardLayoutSetName(subtype.getRawSubtype());
     }