MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
      
        startService();
    }

    private void startMyService(){
        Intent serviceIntent = new Intent(this, MyService.class);
        startService(serviceIntent);
    }
}