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

onAttachedToWindow();

getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);//Запрет на гашения экнара
 ///...... что то делаем 
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); //удаляем запрет на гашения экрана


}




@Override
    public void onAttachedToWindow() {
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON,
                WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
    }

 if(Build.VERSION.SDK_INT<19)
      {// Для версий ниже 19 API
  	  Log.i("Запуск 1 - "+Build.VERSION.SDK_INT,str);  
      pi = PendingIntent.getBroadcast(getBaseContext(), 0, intentalarm, PendingIntent.FLAG_CANCEL_CURRENT); 	         
      manager2.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis()+timeAl*1000, pi); 

      }
    if(Build.VERSION.SDK_INT>=19)
      { // для версий выше 18 API
  	  Log.i("Запуск 2 -  "+Build.VERSION.SDK_INT,str); 
      pi = PendingIntent.getBroadcast(getBaseContext(), 0, intentalarm, PendingIntent.FLAG_CANCEL_CURRENT);  
      manager2.setExact(AlarmManager.RTC_WAKEUP,System.currentTimeMillis()+timeAl*1000, pi);

      }