Merge "Enables registering/unregistering multiple update listeners." into pi-dev

1 files changed, 38 insertions, 11 deletions

diff --git a/car-lib/src/android/car/user/CarUserManagerHelper.java b/car-lib/src/android/car/user/CarUserManagerHelper.java
index db28d21cba..c5885477ab 100644
--- a/car-lib/src/android/car/user/CarUserManagerHelper.java
+++ b/car-lib/src/android/car/user/CarUserManagerHelper.java
@@ -38,6 +38,7 @@ import com.android.internal.util.UserIcons;
 
 import com.google.android.collect.Sets;
 
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
@@ -67,15 +68,23 @@ public class CarUserManagerHelper {
     private final ActivityManager mActivityManager;
     private int mLastActiveUser = UserHandle.USER_SYSTEM;
     private Bitmap mDefaultGuestUserIcon;
-    private OnUsersUpdateListener mUpdateListener;
+    private ArrayList<OnUsersUpdateListener> mUpdateListeners;
     private final BroadcastReceiver mUserChangeReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
-            mUpdateListener.onUsersUpdate();
+            ArrayList<OnUsersUpdateListener> copyOfUpdateListeners;
+            synchronized (mUpdateListeners) {
+                copyOfUpdateListeners = new ArrayList(mUpdateListeners);
+            }
+
+            for (OnUsersUpdateListener listener : copyOfUpdateListeners) {
+                listener.onUsersUpdate();
+            }
         }
     };
 
     public CarUserManagerHelper(Context context) {
+        mUpdateListeners = new ArrayList<>();
         mContext = context.getApplicationContext();
         mUserManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
         mActivityManager = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);
@@ -84,24 +93,42 @@ public class CarUserManagerHelper {
     /**
      * Registers a listener for updates to all users - removing, adding users or changing user info.
      *
-     * <p> Best practise is to keep one listener per helper.
-     *
      * @param listener Instance of {@link OnUsersUpdateListener}.
      */
     public void registerOnUsersUpdateListener(OnUsersUpdateListener listener) {
-        if (mUpdateListener != null) {
-            unregisterOnUsersUpdateListener();
+        if (listener == null) {
+            return;
         }
 
-        mUpdateListener = listener;
-        registerReceiver();
+        synchronized (mUpdateListeners) {
+            if (mUpdateListeners.isEmpty()) {
+                // First listener being added, register receiver.
+                registerReceiver();
+            }
+
+            if (!mUpdateListeners.contains(listener)) {
+                mUpdateListeners.add(listener);
+            }
+        }
     }
 
     /**
-     * Unregisters on user update listener by unregistering {@code BroadcastReceiver}.
+     * Unregisters on user update listener.
+     * Unregisters {@code BroadcastReceiver} if no listeners remain.
+     *
+     * @param listener Instance of {@link OnUsersUpdateListener} to unregister.
      */
-    public void unregisterOnUsersUpdateListener() {
-        unregisterReceiver();
+    public void unregisterOnUsersUpdateListener(OnUsersUpdateListener listener) {
+        synchronized (mUpdateListeners) {
+            if (mUpdateListeners.contains(listener)) {
+                mUpdateListeners.remove(listener);
+
+                if (mUpdateListeners.isEmpty()) {
+                    // No more listeners, unregister broadcast receiver.
+                    unregisterReceiver();
+                }
+            }
+        }
     }
 
     /**