Small cleanup or DataStore API javadoc.

There is also change in PreferenceManager.getSharedPreferences. The
original was not always returning null in case mPreferenceDataStore is
not null. That was contradictory with the java doc and conufing during
the runtime. Added tests for it.

Test: Separate CTS (2) being submitted along this one, see the topic.
Bug: b/34322039
Change-Id: I78a6758a674c3c8139bbe66ec17f2e29ca847828

1 files changed, 20 insertions, 13 deletions

diff --git a/core/java/android/preference/PreferenceManager.java b/core/java/android/preference/PreferenceManager.java
index 14b748a9c6df..ea32dfd7f919 100644
--- a/core/java/android/preference/PreferenceManager.java
+++ b/core/java/android/preference/PreferenceManager.java
@@ -93,8 +93,8 @@ public class PreferenceManager {
     private SharedPreferences mSharedPreferences;
 
     /**
-     * Data store to be used by the Preferences or null if {@link android.content.SharedPreferences}
-     * should be used.
+     * Data store to be used by the Preferences or {@code null} if
+     * {@link android.content.SharedPreferences} should be used.
      */
     @Nullable
     private PreferenceDataStore mPreferenceDataStore;
@@ -484,11 +484,16 @@ public class PreferenceManager {
     /**
      * Gets a {@link SharedPreferences} instance that preferences managed by this will use.
      *
-     * @return A {@link SharedPreferences} instance pointing to the file that contains the values of
-     * preferences that are managed by this or null if {@link PreferenceDataStore} is used instead.
+     * @return a {@link SharedPreferences} instance pointing to the file that contains the values of
+     *         preferences that are managed by this PreferenceManager. If a
+     *         {@link PreferenceDataStore} has been set, this method returns {@code null}.
      */
     public SharedPreferences getSharedPreferences() {
-        if (mSharedPreferences == null && getPreferenceDataStore() == null) {
+        if (mPreferenceDataStore != null) {
+            return null;
+        }
+
+        if (mSharedPreferences == null) {
             final Context storageContext;
             switch (mStorage) {
                 case STORAGE_DEVICE_PROTECTED:
@@ -564,8 +569,8 @@ public class PreferenceManager {
     /**
      * Finds a {@link Preference} based on its key.
      *
-     * @param key The key of the preference to retrieve.
-     * @return The {@link Preference} with the key, or null.
+     * @param key the key of the preference to retrieve
+     * @return the {@link Preference} with the key, or {@code null}
      * @see PreferenceGroup#findPreference(CharSequence)
      */
     @Nullable
@@ -659,11 +664,11 @@ public class PreferenceManager {
 
     /**
      * Returns an editor to use when modifying the shared preferences.
-     * <p>
-     * Do NOT commit unless {@link #shouldCommit()} returns true.
      *
-     * @return An editor to use to write to shared preferences or null if
-     * {@link PreferenceDataStore} is used instead.
+     * <p>Do NOT commit unless {@link #shouldCommit()} returns true.
+     *
+     * @return an editor to use to write to shared preferences. If a {@link PreferenceDataStore}
+     *         has been set, this method returns {@code null}.
      * @see #shouldCommit()
      */
     SharedPreferences.Editor getEditor() {
@@ -687,6 +692,8 @@ public class PreferenceManager {
      * {@link #getEditor()}. This will return false in cases where the writes
      * should be batched, for example when inflating preferences from XML.
      *
+     * <p>If preferences are using {@link PreferenceDataStore} this value is irrelevant.
+     *
      * @return Whether the client should commit.
      */
     boolean shouldCommit() {
@@ -711,8 +718,8 @@ public class PreferenceManager {
      * Returns the activity that shows the preferences. This is useful for doing
      * managed queries, but in most cases the use of {@link #getContext()} is
      * preferred.
-     * <p>
-     * This will return null if this class was instantiated with a Context
+     *
+     * <p>This will return {@code null} if this class was instantiated with a Context
      * instead of Activity. For example, when setting the default values.
      *
      * @return The activity that shows the preferences.