How can I insert data into a Room database using Java in Android?

Introduction

Hello!

I’d be happy to help you insert data into a Room database using Java in Android. Room is a popular database library for Android that provides an easy-to-use SQLite database solution with built-in support for live data, MVVM architecture, and TypeSafe queries. In this guide, we will explore how to create a Room database, define entities, and insert data.

**Creating a Room Database**

First, let’s create a Room database. Create a new Kotlin or Java class that extends `RoomDatabase` and annotate it with `@Database`.

For instance:

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

Defining Entities

Next, define the entity classes that represent your data. Create a new Kotlin or Java class and annotate it with @Entity.

For example:

@Entity(tableName  "users")
public static class UserEntity {
    @PrimaryKey(autoGenerate  true)
    private int id;
    private String name;
    private int age;

    public UserEntity(String name, int age) {
        this.name  name;
        this.age  age;
    }
}

Accessing the Database

Now, we need to access the database in order to insert data. Create an abstract method that returns a DAO (Data Access Object) of your entity class:

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

    public abstract UserDao userDao();
}

Defining DAOs

Next, create a UserDao interface that extends RoomDao<UserEntity>.

For example:

<h2>@Dao</h2>
public interface UserDao {
<h3>    @Insert</h3>
    void insert(UserEntity user);
}

Inserting Data

Finally, we can now insert data into the database. Obtain an instance of your AppDatabase, then your UserDao, and call the insert() method:

@MainThread
public static void insertUser(String name, int age) {
    AppDatabase db  Room.databaseBuilder(ContextCompat.getApplicationContext(context), AppDatabase.class, "app-db").build();
    UserDao userDao  db.userDao();
    UserEntity newUser  new UserEntity(name, age);
    userDao.insert(newUser);
}

Summary

In this guide, we learned how to insert data into a Room database using Java in Android. We started by creating a Room database and defining entities. Next, we accessed the database by creating a DAO, then inserted data using the insert() method.