Android Room 1 - chuwuwang/ReadingNote GitHub Wiki

dependencies {
    def room_version = "2.2.5"

    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version" // For Kotlin use kapt instead of annotationProcessor

    // optional - Kotlin Extensions and Coroutines support for Room
    implementation "androidx.room:room-ktx:$room_version"

    // optional - RxJava support for Room
    implementation "androidx.room:room-rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "androidx.room:room-guava:$room_version"

    // Test helpers
    testImplementation "androidx.room:room-testing:$room_version"
}

android {
    ...
    defaultConfig {
        ...
        javaCompileOptions {
            annotationProcessorOptions {
                arguments = [
                    "room.schemaLocation":"$projectDir/schemas".toString(),
                    "room.incremental":"true",
                    "room.expandProjection":"true"]
            }
        }
    }
}

@Entity( primaryKeys = {"firstName", "lastName"} )
public class User {
    public String firstName;
    public String lastName;
}

@Entity(tableName = "users")
public class User {
    @PrimaryKey
    public int id;

    @ColumnInfo(name = "first_name")
    public String firstName;

    @ColumnInfo(name = "last_name")
    public String lastName;
}

@Entity( indices = { @Index(value = {"first_name", "last_name"}, unique = true) } )
class User {
    @PrimaryKey
    public int id;

    @ColumnInfo(name = "first_name")
    public String firstName;

    @ColumnInfo(name = "last_name")
    public String lastName;

    @Ignore
    Bitmap picture;
}

class Address {
    public String street;
    public String state;
    public String city;

    @ColumnInfo(name = "post_code")
    public int postCode;
}

@Entity
class User {
    @PrimaryKey
    public int id;

    public String firstName;

    @Embedded
    public Address address;
}

public class User {
  @PrimaryKey(autoGenerate = true) public int id;
  public String firstName;
  public String lastName;
  @Embedded(prefix = "first")
  Address address;
  @Embedded(prefix = "second")
  AddressTwo addressTwo;
}

@Dao
public interface MyDao {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    public void insertUsers(User... users);

    @Insert
    public void insertBothUsers(User user1, User user2);

    @Insert
    public void insertUsersAndFriends(User user, List<User> friends);
}

@Dao
public interface MyDao {
    @Update
    public void updateUsers(User... users);
}

@Dao
public interface MyDao {
    @Delete
    public void deleteUsers(User... users);
}

@Dao
public interface MyDao {
    @Query("SELECT * FROM user")
    public User[] loadAllUsers();

    @Query("SELECT * FROM user WHERE age > :minAge")
    public User[] loadAllUsersOlderThan(int minAge);

    @Query("SELECT first_name, last_name FROM user WHERE region IN (:regions)")
    public LiveData<List<User>> loadUsersFromRegionsSync(List<String> regions);

    @Query("SELECT * FROM user WHERE age > :minAge LIMIT 5")
    public Cursor loadRawUsersOlderThan(int minAge);
}

@Dao
public interface MyDao {
    @Query("SELECT first_name, last_name FROM user WHERE region IN (:regions)")
    public LiveData<List<User>> loadUsersFromRegionsSync(List<String> regions);
}

@Dao
public interface MyDao {
    @Query("SELECT * from user where id = :id LIMIT 1")
    public Flowable<User> loadUserById(int id);

    // Emits the number of users added to the database.
    @Insert
    public Maybe<Integer> insertLargeNumberOfUsers(List<User> users);

    // Makes sure that the operation finishes successfully.
    @Insert
    public Completable insertLargeNumberOfUsers(User... users);

    /* Emits the number of users removed from the database. Always emits at
       least one user. */
    @Delete
    public Single<Integer> deleteUsers(List<User> users);
}

public class NameTuple {
    @ColumnInfo(name="first_name")
    public String firstName;

    @ColumnInfo(name="last_name")
    public String lastName;
}

@Dao
public interface MyDao {
    @Query("SELECT first_name, last_name FROM user")
    public List<NameTuple> loadFullName();
}

public class Converters {

    @TypeConverter
    public static Date fromTimestamp(Long value) {
        return value == null ? null : new Date(value);
    }

    @TypeConverter
    public static Long dateToTimestamp(Date date) {
        return date == null ? null : date.getTime();
    }

}

@Database(entities = {User.java}, version = 1)
@TypeConverters( { Converter.class } )
public abstract class AppDatabase extends RoomDatabase {
    public abstract UserDao userDao();
}

@Entity
public class User {
    ...
    private Date birthday;
}

 Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, "user.db")
 .allowMainThreadQueries()
 .build();