public class ServiceBootStart extends BroadcastReceiver {
      @Override
      public void onReceive(Context context, Intent intent) {
        if ("android.intent.action.BOOT_COMPLETED".equals(intent.getAction())) {
          Intent serviceLauncher = new Intent(context, ServiceExample.class);
          context.startService(serviceLauncher);
          Log.v(this.getClass().getName(), "Service loaded while device boot.");
        }
      }
    }

<receiver android:name=".service.ServiceBootStart" android:enabled="true" android:exported="false">
                   <intent-filter>
                      <action android:name="android.intent.action.BOOT_COMPLETED"/>
                    </intent-filter>
              </receiver>
`<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>`

public boolean isServiceRunning(String serviceClassName){
       ActivityManager activityManager = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
       List<RunningServiceInfo> services = activityManager.getRunningServices(Integer.MAX_VALUE);

      for (RunningServiceInfo runningServiceInfo : services) {
          if (runningServiceInfo.service.getClassName().equals(serviceClassName)){
              return true;
          }
      }
      return false;
   }

@Override
     public boolean onKeyDown(int keyCode, KeyEvent event) {// обрабатываю нажатие на кнопку "назад"
         if ((keyCode == KeyEvent.KEYCODE_BACK)) {

                moveTaskToBack(true);
            return true;
         }
         return super.onKeyDown(keyCode, event);
     }