Create a Bound Service on Android

AndroidManifest.xml

<service android:name=".MyService"/>

MyService.java

public class MyService extends Service {

    Binder mBinder = new LocalService();

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }


    public class LocalService extends Binder {

        MyService getService() {
            return MyService.this;
        }

    }

    public String getFirstMessage() {
        return "Message 1";
    }

    public String getSecondMessage() {
        return "Message 2";
    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {

    MyService myService = null;

    Button buttonMessage1;
    Button buttonMessage2;
    TextView textViewOutput;

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

        Intent intent = new Intent(MainActivity.this, MyService.class);
        bindService(intent, serviceConnection, BIND_AUTO_CREATE);

        buttonMessage1 = (Button) findViewById(R.id.buttonMessage1);
        buttonMessage2 = (Button) findViewById(R.id.buttonMessage2);
        textViewOutput = (TextView) findViewById(R.id.textViewOutput);

        buttonMessage1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (myService != null) {
                    textViewOutput.setText(myService.getFirstMessage());
                }
            }
        });

        buttonMessage2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (myService != null) {
                    textViewOutput.setText(myService.getSecondMessage());
                }
            }
        });
    }

    ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            MyService.LocalService localService = (MyService.LocalService) iBinder;
            myService = localService.getService();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            myService = null;
        }
    };

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

        unbindService(serviceConnection);
        myService = null;
    }
}

References
https://www.youtube.com/watch?v=PUxC6vzEEgg
https://github.com/mhdr/AndroidSamples/tree/master/101

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