AppDatabase.java

public abstract class AppDatabase extends RoomDatabase {
  private static final String TAG = "AppDatabase";
  private static volatile AppDatabase INSTANCE;
  
  public static AppDatabase getInstance(Context context) {
    if (INSTANCE == null) {
      synchronized (AppDatabase.class) {
        if (INSTANCE == null) {
          INSTANCE = Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, 'appdatabase.db').build();
        }
      }
    }
    return INSTANCE;
  }
}