SQLite database: Writing and reading data between multiple activities within Android Studio

Question

Using Android studio and the SQLite database:

I have an activity which populates a SQLite database with a few data types per entry.

I want to be able to have another activity that can read this data however, I am not sure how to access the same database via another activity. At the moment I'm not sure if I should pass it as a bundle or whether there is access method.

Thanks in advance

Answer 1

There are multiple ways depending on your needs. The usual is:

1. You save data to the database and return the primary key(s)
2. If you need another activity to use the data, you pass the the primary key via startActivity(new Intent(context, OtherClass.class).putExtra("id", <id from db>));
3. In the other activity, you do int id= getIntent().getIntExtra("id",0);
4. However you access the database, you run the SELECT query on the retrieved id to get the data from SQLite

Maybe this tutorial for Room will help: https://developer.android.com/training/data-storage/room/index.html

Answer 2

First create a new class eg:- Data

create public static String userid; in it

then use Data.userid = sqlitedata and then you can use Data.userid anywhere in your project it will return the same value...

Answer 3

That's super easy.

Let's say this is your database defined this way if you use Room library.

@Database(
entities = [UserSchema::class],
version = 1,
exportSchema = false)

abstract class UserDatabase : RoomDatabase() {
abstract  fun userDoa(): UserDao

companion object {
    private var instance: UserDatabase? = null
    fun getInstance(context: Context): UserDatabase? {
        if (instance == null) {
            synchronized(LmdDatabase::class) {
                instance = Room.databaseBuilder(
                    context,
                    UserDatabase::class.java,
                    Constants.USER_DATABASE
                ).addMigrations()
                    .fallbackToDestructiveMigration()
                    .build()
            }
        }
        return instance
    }

    fun destroyInstance() {
        instance?.close()
        instance = null
    }
}
}

Here is your user entity definition:

@Entity(tableName = "user_table")
data class UserSchema(
    @PrimaryKey
    @ColumnInfo(name = "user_id") val userId:String
)

Here is your doa to delete and remove user objects from database

@Dao
interface UserDao {

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    suspend fun insert(vararg userSchema: UserSchema)

    @Delete
    suspend fun delete(vararg userSchema: UserSchema)

    @Query("SELECT * FROM user_table")
    fun getAll(): LiveData<List<UserSchema>>
}

Your first activity can call insert from coroutine context to insert data eg user into table using suspend insert method. The other activity can observe that table or database for data change using getAll() method