Saving Data Using the Room Persistence Library

Room provides an abstraction layer over SQLite to allow fluent database access while harnessing the full power of SQLite.

There are 3 major components in Room:

1. Database
2. Entity
3. Dao

In existing project -

Very basic usages and setup of room data base has been shown via user example.

Basic crucks-

*. Setup of data base

AppDatabase - create db

@Database(entities = {User.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {

appDatabase = Room.databaseBuilder(context.getApplicationContext(),
                    AppDatabase.class, "database-name").build();             

*. UserDao - interface to provide access on db-

@Dao
public interface UserDao {
    @Query("SELECT * FROM user")
    List<User> getAll();

//init service

*. Initilize service where you want to use room db-

private UserServiceImpl userService;
userService = new UserServiceImpl(LoginActivity.this);

*. From do in background save objects in db

            User user = new User();
            user.setUid(new Random().nextInt());
            user.setEmail(mEmail);
            user.setPassword(mPassword);
            user.setFirstName("First Name");
            user.setLastName("Last Name");
            userService.insertAll(user);
            users = userService.getAll();

*. Simple method to get db in background thread and showing data on UI-

 private void getUsersFromDB() {
        new AsyncTask<Void, Void, Void>() {
            @Override
            protected Void doInBackground(Void... params) {
                users = userService.getAll();
                return null;
            }
            @Override
            protected void onPostExecute(Void agentsCount) {
                usersTextView.setText("Users \n\n " + users);
            }
        }.execute();

https://developer.android.com/images/training/data-storage/room_architecture.png

Screen shots