Refactored all the other classes to support multi user. Clearing the app data is required before launching the app.

app/src/main/java/User/UserData.java

@@ -1,13 +1,18 @@
 package User;
 
+import androidx.annotation.NonNull;
 import androidx.room.ColumnInfo;
 import androidx.room.Entity;
-import androidx.annotation.NonNull;
-
-import SubscribedUserDatabase.SubscribedUserData;
+import androidx.room.PrimaryKey;
 
 @Entity(tableName = "users")
-public class UserData extends SubscribedUserData {
+public class UserData {
+    @PrimaryKey
+    @NonNull
+    @ColumnInfo(name = "name")
+    private String name;
+    @ColumnInfo(name = "icon")
+    private String iconUrl;
     @ColumnInfo(name = "banner")
     private String banner;
     @ColumnInfo(name = "karma")
@@ -20,7 +25,8 @@ public class UserData extends SubscribedUserData {
     private boolean canBeFollowed;
 
     public UserData(@NonNull String name, String iconUrl, String banner, int karma, boolean isGold, boolean isFriend, boolean canBeFollowed) {
-        super(name, iconUrl);
+        this.name = name;
+        this.iconUrl = iconUrl;
         this.banner = banner;
         this.karma = karma;
         this.isGold = isGold;
@@ -28,6 +34,15 @@ public class UserData extends SubscribedUserData {
         this.canBeFollowed = canBeFollowed;
     }
 
+    @NonNull
+    public String getName() {
+        return name;
+    }
+
+    public String getIconUrl() {
+        return iconUrl;
+    }
+
     public String getBanner() {
         return banner;
     }

app/src/main/java/User/UserRepository.java

@@ -1,16 +1,17 @@
 package User;
 
-import android.app.Application;
-import androidx.lifecycle.LiveData;
 import android.os.AsyncTask;
 
+import androidx.lifecycle.LiveData;
+
+import ml.docilealligator.infinityforreddit.RedditDataRoomDatabase;
+
 public class UserRepository {
     private UserDao mUserDao;
     private LiveData<UserData> mUserLiveData;
 
-    UserRepository(Application application, String userName) {
-        mUserDao = UserRoomDatabase.getDatabase(application).userDao();
-
+    UserRepository(RedditDataRoomDatabase redditDataRoomDatabase, String userName) {
+        mUserDao = redditDataRoomDatabase.userDao();
         mUserLiveData = mUserDao.getUserLiveData(userName);
     }
 

app/src/main/java/User/UserRoomDatabase.java

@@ -1,26 +0,0 @@
-package User;
-
-import androidx.room.Database;
-import androidx.room.Room;
-import androidx.room.RoomDatabase;
-import android.content.Context;
-
-@Database(entities = {UserData.class}, version = 1)
-public abstract class UserRoomDatabase extends RoomDatabase {
-    private static UserRoomDatabase INSTANCE;
-
-    public abstract UserDao userDao();
-
-    public static UserRoomDatabase getDatabase(final Context context) {
-        if(INSTANCE == null) {
-            synchronized (UserRoomDatabase.class) {
-                if(INSTANCE == null) {
-                    INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
-                            UserRoomDatabase.class, "users")
-                            .build();
-                }
-            }
-        }
-        return INSTANCE;
-    }
-}

app/src/main/java/User/UserViewModel.java

@@ -7,13 +7,15 @@ import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.annotation.NonNull;
 
+import ml.docilealligator.infinityforreddit.RedditDataRoomDatabase;
+
 public class UserViewModel extends AndroidViewModel {
     private UserRepository mSubredditRepository;
     private LiveData<UserData> mUserLiveData;
 
-    public UserViewModel(Application application, String id) {
+    public UserViewModel(Application application, RedditDataRoomDatabase redditDataRoomDatabase, String id) {
         super(application);
-        mSubredditRepository = new UserRepository(application, id);
+        mSubredditRepository = new UserRepository(redditDataRoomDatabase, id);
         mUserLiveData = mSubredditRepository.getUserLiveData();
     }
 
@@ -29,18 +31,19 @@ public class UserViewModel extends AndroidViewModel {
 
         @NonNull
         private final Application mApplication;
+        private final RedditDataRoomDatabase mRedditDataRoomDatabase;
+        private final String mUsername;
 
-        private final String userName;
-
-        public Factory(@NonNull Application application, String userName) {
+        public Factory(@NonNull Application application, RedditDataRoomDatabase redditDataRoomDatabase, String username) {
             mApplication = application;
-            this.userName = userName;
+            mRedditDataRoomDatabase = redditDataRoomDatabase;
+            mUsername = username;
         }
 
         @Override
         public <T extends ViewModel> T create(Class<T> modelClass) {
             //noinspection unchecked
-            return (T) new UserViewModel(mApplication, userName);
+            return (T) new UserViewModel(mApplication, mRedditDataRoomDatabase, mUsername);
         }
     }
 }