Broadcast Receiver not calling Service while app w

Question

My target was Restarting the Service when app is in background or even killed from home page by sweeping. App & Service is working nice while app is in foreground and background but while I killed the app by force(sweeping out from home page), the Service stopped working. That's okay but I implemented a Broadcast Receiver to restart the Service but it seems like its (Broadcast Receiver) not even called itself or the Service while app was killed forcefully / sweeping from home page.

My device is : Xiaomi Redmi Note 4

I included my codes here :

MainActivity.java

package com.turzo.servicetest;

import android.app.ActivityManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    private String TAG = "ServiceTest";
    Intent mServiceIntent;
    private SensorService mSensorService;

    Context ctx;

    public Context getCtx() {
        return ctx;
    }



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

        mSensorService = new SensorService(getCtx());
        mServiceIntent = new Intent(getCtx(), mSensorService.getClass());
        if (!isMyServiceRunning(mSensorService.getClass())) {
            startService(mServiceIntent);
        }

    }

    private boolean isMyServiceRunning(Class<?> serviceClass) {
        ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
            if (serviceClass.getName().equals(service.service.getClassName())) {
                Log.i (TAG, true+"");
                return true;
            }
        }
        Log.i (TAG, false+"");
        return false;
    }


    @Override
    protected void onDestroy() {
       stopService(mServiceIntent);
        Log.i(TAG, "onDestroy!");
        super.onDestroy();

    }

    public void registerRec(){


        SensorRestarterBroadcastReceiver myreceiver = new SensorRestarterBroadcastReceiver();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        registerReceiver((BroadcastReceiver) myreceiver, intentFilter);
    }







}

SensorService.java

package com.turzo.servicetest;

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;

import java.util.Timer;
import java.util.TimerTask;


public class SensorService extends Service {
    public int counter=0;
    private String TAG = "ServiceTest";
    public SensorService(Context applicationContext) {
        super();
        Log.i(TAG , "here I am!");
    }

    public SensorService() {
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        super.onStartCommand(intent, flags, startId);

        startTimer();
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.i(TAG , "ondestroy!");
        Intent broadcastIntent = new Intent("com.turzo.servicetest.ActivityRecognition.RestartSensor");
        sendBroadcast(broadcastIntent);
        stoptimertask();
    }

    private Timer timer;
    private TimerTask timerTask;
    long oldTime=0;
    public void startTimer() {
        //set a new Timer
        timer = new Timer();

        //initialize the TimerTask's job
        initializeTimerTask();

        //schedule the timer, to wake up every 1 second
        timer.schedule(timerTask, 1000, 1000); //
    }

    /**
     * it sets the timer to print the counter every x seconds
     */
    public void initializeTimerTask() {
        timerTask = new TimerTask() {
            public void run() {
                Log.i(TAG , "in timer ++++  "+ (counter++));
            }
        };
    }

    /**
     * not needed
     */
    public void stoptimertask() {
        //stop the timer, if it's not already null
        if (timer != null) {
            timer.cancel();
            timer = null;
        }
    }

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


} 

SensorRestarterBroadcastReceiver.java

package com.turzo.servicetest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;


public class SensorRestarterBroadcastReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i(SensorRestarterBroadcastReceiver.class.getSimpleName(), "Service Stops! Oooooooooooooppppssssss!!!!");

        context.startService(new Intent(context, SensorService.class));
    }

}

AndroidManifext.xml

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.turzo.servicetest">

    <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="com.turzo.servicetest.SensorService"
            android:enabled="true" >
        </service>

        <receiver
            android:name="com.turzo.servicetest.SensorRestarterBroadcastReceiver"
            android:enabled="true"
            android:exported="true"
            android:label="RestartServiceWhenStopped">
            <intent-filter>
                <action android:name="com.turzo.servicetest.ActivityRecognition.RestartSensor"/>
            </intent-filter>
        </receiver>


    </application>

</manifest> 

Answer 1

You should restart Service in onTaskRemoved().

  @Override
    public void onTaskRemoved(Intent rootIntent) {
        Intent restartService = new Intent(getApplicationContext(),
                this.getClass());
        restartService.setPackage(getPackageName());
        PendingIntent restartServicePI = PendingIntent.getService(
                getApplicationContext(), 1, restartService,
                PendingIntent.FLAG_ONE_SHOT);
        AlarmManager alarmService = (AlarmManager) getApplicationContext().getSystemService(Context.ALARM_SERVICE);
        alarmService.set(AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime() + 1000, restartServicePI);
    }

NOTE:- Starting from android O . You can not call startService.

The startService() method now throws an IllegalStateException if an app targeting Android 8.0 tries to use that method in a situation when it isn't permitted to create background services.

This does not apply to foreground services, which are noticeable to the user. It can run in background with a notification on top. By default, these restrictions only apply to apps that target Android 8.0 (API level 26) or higher. However, users can enable most of these restrictions for any app from the Settings screen, even if the app targets an API level lower than 26. So in case if user enables the restrictions for below API 26 your Service will not work.
Read Background Execution Limits.

So Try to avoid using Service if you can . Make use of WorkManager if it fits the requirements.