...
    @Query("UPDATE HeroList SET mFavorite=0")
    void listToFalse();

    @Update(onConflict = OnConflictStrategy.REPLACE)
    void updateList(DatabaseHero databaseHero);

    @Query("SELECT * FROM HeroList WHERE id=:position")
    DatabaseHero getHeroByPosition(int position);

    @Query("SELECT * FROM Herolist")
    LiveData<List<DatabaseHero>> loadAllHeroes();

@Override
    protected void onCreate(Bundle savedInstanceState) {
....
        final LiveData<List<DatabaseHero>> heroList =
        dbHelper.taskDao().loadAllHeroes();
        heroList.observe(this, new Observer<List<DatabaseHero>>() {
            @Override
            public void onChanged(@Nullable List<DatabaseHero> list) {
                mHeroesAdapter.setTasks(list);
            }
        });
...
@Override
        public void onListItemClick ( final int position){
            AppExecutors.getInstance().diskIO().execute(new Runnable() {
                @Override
                public void run() {
                    boolean favorite = true;
                    if (dbHelper.taskDao().favoriteState(position)) {
                        favorite = false;
                    }
                  dbHelper.taskDao().listToFalse();
                  DatabaseHero
                  databaseHero=dbHelper.taskDao().getHeroByPosition(position);
                  databaseHero.setFavorite(true);
                  dbHelper.taskDao().updateList(databaseHero);

                }
            });

        }

@Entity(tableName = "HeroList")
public class DatabaseHero {

    @PrimaryKey(autoGenerate = true)
    private int id;
    private String mTitle;
    private String mAbilities;
    private String mImageUrl;
    private boolean mFavorite;

 //getters and setters...