Room Library

DB

@Database(entities = {DBVersion.class, CafeteriaData.class, SearchHistory.class}, version = 2)
public abstract class AppDatabase extends RoomDatabase {
    public abstract DBVersionDao getDBVersionDao();
    public abstract CafeteriaDataDao getCafeteriaDataDao();
    public abstract SearchHistoryDao getSearchHistoryDao();

    private static volatile AppDatabase INSTANCE;

    public static AppDatabase getInstance(Context context) {
        if (null == INSTANCE) {
            synchronized (AppDatabase.class) {
                INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
                        AppDatabase.class, "word_database")
                        .build();

            }
        }
        return INSTANCE;
    }

}

 

Dao

@Dao
public interface DBVersionDao {

    @Insert
    public void insert(DBVersion version);

    @Query("SELECT * FROM version_table")
    public DBVersion get();

    @Update
    public int update(DBVersion version);

    @Query("DELETE FROM version_table")
    public void deleteAll();
}

 

Entity

@Entity(tableName = "version_table")
public class DBVersion {
    @PrimaryKey(autoGenerate = true)
    long id;
    int version;

    public DBVersion(int version) {
        this.version = version;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public int getVersion() {
        return version;
    }

    public void setVersion(int version) {
        this.version = version;
    }


}

 

    def room_version = "1.1.1"

    implementation "android.arch.persistence.room:runtime:$room_version"
    implementation 'com.android.support:support-v4:26.1.0'
    annotationProcessor "android.arch.persistence.room:compiler:$room_version"

 

  DBVersion dbVersion = dbVersionDao.get();
      
  dbVersionDao.insert(new DBVersion(version));
        
  dbVersion.setVersion(version);

  dbVersionDao.update(dbVersion);