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The service is part of the program that runs in the background for long-term operations without the need to interact with the user, and even works when the main program is closed.

A service can have basically two modes –

A service has lifecycle callback methods that you can implement to monitor changes in service status and get the job done right. The following diagram on the left shows the service lifecycle created with startService () and the diagram on the right shows the life cycle when creating a service with bindService ():

To create a service, create a Java class that is derived from the base Service class. The Service class defines the various callback methods, the most important of which are listed below. You do not need to run all callback methods. However, it is important that you understand each and implement things to make sure the program works as expected.

The following service shows each of the life cycle methods –

package com.tutorialspoint;

import android.app.Service;

import android.os.IBinder;

import android.content.Intent;

import android.os.Bundle;

public class HelloService extends Service {

/ ** indicates how to behave if the service is killed * /

int mStartMode;

/ ** interface for clients that bind * /

IBinder mBinder;

/ ** indicates whether onRebind should be used * /

boolean mAllowRebind;

/ ** Called when the service is being created. * /

@Override

public void onCreate () {

}

/ ** The service is starting, due to a call to startService () * /

@Override

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

return mStartMode;

}

/ ** A client is binding to the service with bindService () * /

@Override

public IBinder onBind (Intent intent) {

return mBinder;

}

/ ** Called when all clients have unbound with unbindService () * /

@Override

public boolean onUnbind (Intent intent) {

return mAllowRebind;

}

/ ** Called when a client is binding to the service with bindService () * /

@Override

public void onRebind (Intent intent) {

}

/ ** Called when The service is no longer used and is being destroyed * /

@Override

public void onDestroy () {

}

}

Example

This example will acquaint you with the steps of creating an Android service. To modify the Android application that we created in the Hello World example section, follow the steps below –

Below you can see the contents of the MainActivity.java file. This file contains each of the basic life cycle methods. To start and stop the service, we have added the methods startService () and stopService ().

package com.example.tutorialspoint7.myapplication;

import android.content.Intent;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.os.Bundle;

import android.app.Activity;

import android.util.Log;

import android.view.View;

public class MainActivity extends Activity {

String msg = “Android:”;

/ ** Called when the activity is first created. * /

@Override

public void onCreate (Bundle savedInstanceState) {

super.onCreate (savedInstanceState);

setContentView (R.layout.activity_main);

Log.d (msg, “The onCreate () event”);

}

public void startService (View view) {

startService (new Intent (getBaseContext (), MyService.class));

}

// Method to stop the service

public void stopService (View view) {

stopService (new Intent (getBaseContext (), MyService.class));

}

}

Below is the content of the MyService.java file. This file can implement one or more service-related methods based on the required conditions. Currently we have implemented only two methods onStartCommand () and onDestroy () –

package com.example.tutorialspoint7.myapplication;

import android.app.Service;

import android.content.Intent;

import android.os.IBinder;

import android.support.annotation.Nullable;

import android.widget.Toast;

/ **

* Created by TutorialsPoint7 on 8/23/2016.

* /

public class MyService extends Service {

@Nullable

@Override

public IBinder onBind (Intent intent) {

return null;

}

@Override

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

// Let it continue running until it is stopped.

Toast.makeText (this, “Service Started”, Toast.LENGTH_LONG) .show ();

return START_STICKY;

}

@Override

public void onDestroy () {

super.onDestroy ();

Toast.makeText (this, “Service Destroyed”, Toast.LENGTH_LONG) .show ();

}

}

Below we edit the AndroidManifest.xml file to define the service. Add the <service… /> tag here to introduce the service –

<? xml version = ”1.0 ″ encoding =” utf-8 ″?>

<manifest xmlns: android = ”http://schemas.android.com/apk/res/android”

package = ”com.example.tutorialspoint7.myapplication”>

<application

android: allowBackup = ”true”

android: icon = ”@ mipmap / ic_launcher”

android: label = ”@ string / app_name”

android: supportsRtl = ”true”

android: theme = ”@ style / AppTheme”>

<activity android: name = ”. MainActivity”>

<intent-filter>

<action android: name = ”android.intent.action.MAIN” />

<category android: name = ”android.intent.category.LAUNCHER” />

</intent-filter>

</activity>

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

</application>

</manifest>

Below you will find the contents of the res / layout / activity_main.xml file, to which we have added two buttons.

<RelativeLayout xmlns: android = ”http://schemas.android.com/apk/res/android”

xmlns: tools = ”http://schemas.android.com/tools” android: layout_width = ”match_parent”

android: layout_height = ”match_parent” android: paddingLeft = ”@ dimen / activity_horizontal_margin”

android: paddingRight = ”@ dimen / activity_horizontal_margin”

android: paddingTop = ”@ dimen / activity_vertical_margin”

android: paddingBottom = ”@ dimen / activity_vertical_margin” tools: context = ”. MainActivity”>

<TextView

android: id = ”@ + id / textView1 ″

android: layout_width = ”wrap_content”

android: layout_height = ”wrap_content”

android: text = ”Example of services”

android: layout_alignParentTop = ”true”

android: layout_centerHorizontal = ”true”

android: textSize = ”30dp” />

<TextView

android: id = ”@ + id / textView2 ″

android: layout_width = ”wrap_content”

android: layout_height = ”wrap_content”

android: text = ”Tutorials point“

android: textColor = ”# ff87ff09 ″

android: textSize = ”30dp”

android: layout_above = ”@ + id / imageButton”

android: layout_centerHorizontal = ”true”

android: layout_marginBottom = ”40dp” />

<ImageButton

android: layout_width = ”wrap_content”

android: layout_height = ”wrap_content”

android: id = ”@ + id / imageButton”

android: src = ”@ drawable / abc”

android: layout_centerVertical = ”true”

android: layout_centerHorizontal = ”true” />

<Button

android: layout_width = ”wrap_content”

android: layout_height = ”wrap_content”

android: id = ”@ + id / button2 ″

android: text = ”Start Services”

android: onClick = ”startService”

android: layout_below = ”@ + id / imageButton”

android: layout_centerHorizontal = ”true” />

<Button

android: layout_width = ”wrap_content”

android: layout_height = ”wrap_content”

android: text = ”Stop Services”

android: id = ”@ + id / button”

android: onClick = ”stopService”

android: layout_below = ”@ + id / button2 ″

android: layout_alignLeft = ”@ + id / button2 ″

android: layout_alignStart = ”@ + id / button2 ″

android: layout_alignRight = ”@ + id / button2 ″

android: layout_alignEnd = ”@ + id / button2 ″ />

</RelativeLayout>

We are now running the program. Suppose you created the AVD (Android Virtual Device) while setting up the Android programming environment. To run the program, open one of the activity files and then click on the run icon. Install the Android studio application in AVD and install it. If everything is set up correctly, a simulator window will appear as shown below:

Now to start your service, click on the Start Service button, this button will start the service and according to our programming in the onStartCommand () method, a Service Started message will appear at the bottom of the emulator as follows –

You can click the Stop Service button to stop the service.