如何在android中始终运行服务？

这将使服务开始使用代码。它可以工作，但一旦在设备的堆空间中删除应用程序。它不跑了。再次启动时，它将被执行。如何始终运行该服务？

我想您可能希望在前台运行该服务。这样，即使关闭应用程序，服务也会运行。在服务结束之前会看到一个通知栏（更多信息如下：）

   Can someone explain what problem in this code.

Example code:   

    Intent alarm = new Intent(this.cons, AlarmReceiver.class);
                boolean alarmRunning = (PendingIntent.getBroadcast(this.cons, 0, alarm,
        PendingIntent.FLAG_NO_CREATE) != null);
        if (alarmRunning == false) {
                    PendingIntent pendingIntent = PendingIntent.getBroadcast(this.cons,
                            0, alarm, 0);
                    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
                    alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
                            SystemClock.elapsedRealtime(), 30000, pendingIntent);
                     ComponentName receiver = new ComponentName(cons, AlarmReceiver.class);
         PackageManager pm = cons.getPackageManager();
         pm.setComponentEnabledSetting(receiver,
                                PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
                                PackageManager.DONT_KILL_APP);   
            }