How do I keep Background Service always run in background

Question

I am newbie to android studio and learning about services, I visited this page : https://xjaphx.wordpress.com/2012/07/07/create-a-service-that-does-a-schedule-task/ In which author made a background service as follows: files go like:

So I create my own service called TimeService:

public class TimeService extends Service {
    // constant
    public static final long NOTIFY_INTERVAL = 10 * 1000; // 10 seconds

    // run on another Thread to avoid crash
    private Handler mHandler = new Handler();
    // timer handling
    private Timer mTimer = null;

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

    @Override
    public void onCreate() {
        // cancel if already existed
        if(mTimer != null) {
            mTimer.cancel();
        } else {
            // recreate new
            mTimer = new Timer();
        }
        // schedule task
        mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(), 0, NOTIFY_INTERVAL);
    }

    class TimeDisplayTimerTask extends TimerTask {

        @Override
        public void run() {
            // run on another thread
            mHandler.post(new Runnable() {

                @Override
                public void run() {
                    // display toast
                    Toast.makeText(getApplicationContext(), getDateTime(),
                            Toast.LENGTH_SHORT).show();
                }

            });
        }

        private String getDateTime() {
            // get date time in custom format
            SimpleDateFormat sdf = new SimpleDateFormat("[yyyy/MM/dd - HH:mm:ss]");
            return sdf.format(new Date());
        }

    }

Andoid Manfest.xml

<?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    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=".TimeService"
        android:enabled="true"
        android:exported="true"></service>
</application>

MainActivity.java is :

    package com.example.shubhamrajput.myapplication;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        startService(new Intent(this, TimeService.class));
    }

} I tested this app on my phone ,but it is not working in the background when I terminate it from app tray, I want to make it run forever until user stops it forcefully from settings, How do I change this code? Please provide detailed explanation and also provide modified code ,so that I can understand it.How can I make it a foreground service?

Answer 1

You should not be running service in the background always because of it will use CPU and memory all the time.You will end up having very poor battery backup

You can use Job Scheduler for API level greater than 21 or Firebase Job Dispatcher for below API level 21.Using this, you can fire recurring job in an efficient manner.

Answer 2

You can run the service on different process so it will run always irrespective of the application

In manifest file

<service
   android:name=".TimeService"
  android:enabled="true"
  android:process=":my_process">
</service> 

You can also use START_STICKY or you can follow this Answer for more details.