Intent Service Example.

1.MainActivity.xml

<Button 
    android:id="@+id/btn_start_service"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Start Service"
    xmlns:android="http://schemas.android.com/apk/res/android" />

MainActivity.Java

public class MainActivity extends AppCompatActivity {

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

        //setting button click
        findViewById(R.id.btn_start_service).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                //Creating an intent for sending to service
                Intent intent = new Intent(getApplicationContext(), MyIntentService.class);

                intent.putExtra("id", 101);
                intent.putExtra("msg", "hi");

                //starting service
                startService(intent);
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();

        //register broadcast receiver for the intent MyTaskStatus
        LocalBroadcastManager.getInstance(this).registerReceiver(MyReceiver, new IntentFilter("MyServiceStatus"));
    }


    //Defining broadcast receiver
    private BroadcastReceiver MyReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {

            String message = intent.getStringExtra("serviceMessage");

            Toast.makeText(MainActivity.this, "Received : " + message, Toast.LENGTH_SHORT).show();
        }
    };


    @Override
    protected void onStop()
    {
        super.onStop();

        LocalBroadcastManager.getInstance(this).unregisterReceiver(MyReceiver);
    }

}

MyIntentService.java

public class MyIntentService extends IntentService {

    public MyIntentService() {
        super(MyIntentService.class.getName());
    }

    @Override
    protected void onHandleIntent(Intent intent) {


        //retrieving data from the received intent
        int id = intent.getIntExtra("id",0);
        String message = intent.getStringExtra("msg");

        Log.i("Data  ", "id : "+id+" message : "+ message );
        //-----------------------------------------------


        //Do your long running task here


        //------------------------------------------------

        //Broadcasting some data
        Intent myIntent = new Intent("MyServiceStatus");
        myIntent.putExtra("serviceMessage", "Task done");

        // Send broadcast
        LocalBroadcastManager.getInstance(this).sendBroadcast(myIntent);

    }
}