package org.meicode.boundservices;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.IBinder;
import android.os.SystemClock;
import android.widget.TextView;

/**
* Created By Meisam at meiCode.org
*/

public class MainActivity extends AppCompatActivity {

private boolean isBound = false;
private ExampleService service;

private TextView textView;
private DisplayRandomAsyncTask displayRandomAsyncTask;

private ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
ExampleService.LocalBinder binder = (ExampleService.LocalBinder) iBinder;
service = binder.getService();

isBound = true;
}

@Override
public void onServiceDisconnected(ComponentName componentName) {
isBound = false;
}
};

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

textView = (TextView) findViewById(R.id.textView);

displayRandomAsyncTask = new DisplayRandomAsyncTask();
displayRandomAsyncTask.execute();
}

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

Intent intent = new Intent(this, ExampleService.class);
bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE);
}

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

if (isBound && service != null) {
unbindService(serviceConnection);
}
}

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

if (null != displayRandomAsyncTask) {
if (!displayRandomAsyncTask.isCancelled()) {
displayRandomAsyncTask.cancel(true);
}
}
}

private class DisplayRandomAsyncTask extends AsyncTask<Void, Integer, Void> {
@Override
protected Void doInBackground(Void... voids) {
for (int i=0; i<10; i++) {
if (isBound && service != null) {
publishProgress(service.getRandom());
}

SystemClock.sleep(1000);
}
return null;
}

@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);

textView.setText(String.valueOf(values[0]));
}
}
}
package org.meicode.boundservices;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

import androidx.annotation.Nullable;

import java.util.Random;

/**
* Created by Meisam at meiCode.org
*/

public class ExampleService extends Service {

private IBinder binder = new LocalBinder();
private Random random = new Random();

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

public class LocalBinder extends Binder {
ExampleService getService() {
return ExampleService.this;
}
}

public int getRandom() {
return random.nextInt();
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
<resources>
<string name="app_name">Bound Services</string>
<string name="service_desc">This service downloads stuff</string>
</resources>