@Override

    public int onStartCommand(Intent intent, int flags, int startId) {

        new Thread(){

            public void run() {

                super.run();

                while (true) {

                    System.out.println("Service is running");

                    try {

                        sleep(1000);

                    } catch (InterruptedException e) {

                        e.printStackTrace();

                    }

                }

            }

        }.start();

        return super.onStartCommand(intent, flags, startId);

    }

 protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        findViewById(R.id.btnStartService).setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                startService(new Intent(MainActivity.this, MyService.class));

            }

        });

        findViewById(R.id.btnStopService).setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                stopService(new Intent(MainActivity.this, MyService.class));

            }

        });

    }