How to populate Android Room database table on first run

In this android programming source code example, we are going to populate Android Room database table on first run.

You can copy and adopt this source code example to your android project without reinventing the wheel.

Below is a step by step source code to populate Android Room database table on first run.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="15dp">

    <android.support.design.widget.TextInputLayout
        android:id="@+id/nameinput"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <EditText
            android:id="@+id/name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="@string/name"
            android:inputType="textNoSuggestions"
            android:maxLines="1"
            android:singleLine="true" />
    </android.support.design.widget.TextInputLayout>

    <Button
        android:id="@+id/saveBtn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent"
        android:layout_below="@id/nameinput"
        android:textColor="#ffffff"
        android:text="Save"/>



</RelativeLayout>

MainActivity.java

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import io.reactivex.Completable;
import io.reactivex.CompletableObserver;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.Disposable;
import io.reactivex.functions.Action;
import io.reactivex.schedulers.Schedulers;

public class RoomDatabaseActivity9 extends AppCompatActivity {
    private EditText name;
    private Button save;
    private UserDatabase userDatabase;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_room_database9);
        name = (EditText) findViewById(R.id.name);
        save = (Button) findViewById(R.id.saveBtn);
        userDatabase = UserDatabase.getInstance(this);
        save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String enteredname = name.getText().toString();
                saveUser(enteredname);
            }
        });
    }

    private void saveUser(final String ename){
        Completable.fromAction(new Action() {
            @Override
            public void run() throws Exception {
                User user = new User(ename);
                userDatabase.userDAO().insert(user);
            }
        }).observeOn(AndroidSchedulers.mainThread())
                .subscribeOn(Schedulers.io())
                .subscribe(new CompletableObserver() {
                    @Override
                    public void onSubscribe(Disposable d) {
                    }

                    @Override
                    public void onComplete() {
                        Toast.makeText(RoomDatabaseActivity9.this, "Data store successfully",Toast.LENGTH_LONG).show();
                    }

                    @Override
                    public void onError(Throwable e) {
                        Toast.makeText(RoomDatabaseActivity9.this, "Data not store",Toast.LENGTH_LONG).show();
                    }
                });
    }

    public static void runDb(Context context, UserDatabase userDatabase){
        User user = new User("Inducesmile");
        userDatabase.userDAO().insert(user);
    }
}

UserDatabase.java

import android.arch.persistence.db.SupportSQLiteDatabase;
import android.arch.persistence.room.Database;
import android.arch.persistence.room.Room;
import android.arch.persistence.room.RoomDatabase;
import android.content.Context;
import android.support.annotation.NonNull;

import java.util.concurrent.Executors;

@Database(entities = { User.class }, version = 1, exportSchema = false)
@TypeConverters(TypeConverter13.class)
public abstract class UserDatabase extends RoomDatabase {
    private static final String DB_NAME ="UserDb";
    private static UserDatabase instance;
    public abstract UserDAO userDAO();


    public synchronized static UserDatabase getInstance(final Context context) {
        if (instance == null) {
            instance = Room.databaseBuilder(context, UserDatabase.class, DB_NAME)
                    .addCallback(new Callback() {
                        @Override
                        public void onCreate(@NonNull SupportSQLiteDatabase db) {
                            super.onCreate(db);
                            Executors.newSingleThreadScheduledExecutor().execute(new Runnable() {
                                @Override
                                public void run() {
                                    RoomDatabaseActivity9.runDb(context, getInstance(context));
                                }
                            });
                        }
                    })
                    .allowMainThreadQueries().build();
        }
        return instance;
    }
}

User.java

import android.arch.persistence.room.ColumnInfo;
import android.arch.persistence.room.Entity;
import android.arch.persistence.room.Ignore;
import android.arch.persistence.room.PrimaryKey;

@Entity(tableName = "users")
public class User {
    @PrimaryKey(autoGenerate = true)
    private int id;
    @ColumnInfo(name = "name")
    private String name;
    public User(int id, String name){
        this.id = id;
        this.name = name;
    }
    @Ignore
    public User(String name){
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public String getName() {
        return name;
    }
}

UserDAO.java

import android.arch.persistence.room.Dao;
import android.arch.persistence.room.Delete;
import android.arch.persistence.room.Insert;
import android.arch.persistence.room.Query;
import android.arch.persistence.room.Update;
import java.util.ArrayList;
import java.util.List;

@Dao
public interface UserDAO {
    @Query("select * from users")
    List<User> getuserList();

    @Insert
    public void insert(User user);

    @Update
    public void update(User user);

    @Delete
    public void delete(User user);

}

build.gradle

implementation 'io.reactivex.rxjava2:rxjava:2.1.9'
implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'
implementation 'android.arch.persistence.room:runtime:1.0.0' 
annotationProcessor 'android.arch.persistence.room:compiler:1.0.0'

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