Android線程問題Thread-387

Question

我在使用線程時出現問題。我有他的服務班，我需要檢查更新，然後睡了24小時。

public class SimpleService extends Service { 
    private static final int NOVI_VESTI = 1; 
    private static final int NOVA_OGLASNA = 2; 
    private List<String> titles; 

    @Override 
    public IBinder onBind(Intent arg0) { 
     return null; 
    } 

    @Override 
    public void onCreate() { 
     super.onCreate(); 

     Thread t = new Thread() { 
      @Override 
      public void run() { 
       while (true) { 
        try { 
         String vesti, oglasna; 
         vesti = readRss("http://www.finki.ukim.mk/mk/rss/news"); 
         // readRss("http://www.finki.ukim.mk/mk/rss/news"); 
         // getPrefs("vesti"); 
         if (!vesti.equals(getPrefs("vesti"))) { 
          Context context = SimpleService.this; 
          NotificationManager notificationManager = (NotificationManager) context 
            .getSystemService(NOTIFICATION_SERVICE); 
          Notification updateComplete = new Notification(); 
          updateComplete.icon = R.drawable.ic_launcher; 
          updateComplete.tickerText = context 
            .getText(R.string.newVesti); 
          updateComplete.when = System.currentTimeMillis(); 
          Intent notificationIntent = new Intent(context, 
            Vesti.class); 
          PendingIntent contentIntent = PendingIntent 
            .getActivity(context, 0, 
              notificationIntent, 0); 

          String contentTitle = context.getText(
            R.string.newVesti).toString(); 
          String contentText; 
          contentText = vesti.toString(); 
          updateComplete.setLatestEventInfo(context, 
            contentTitle, contentText, contentIntent); 

          notificationManager.notify(NOVI_VESTI, 
            updateComplete); 

         } 

         oglasna = readRss("http://www.finki.ukim.mk/mk/rss/announcements"); 
         if (!oglasna.equals(getPrefs("oglasna"))) { 

          Context context = SimpleService.this; 
          NotificationManager notificationManager = (NotificationManager) context 
            .getSystemService(NOTIFICATION_SERVICE); 
          Notification updateComplete = new Notification(); 
          updateComplete.icon = R.drawable.ic_launcher; 
          updateComplete.tickerText = context 
            .getText(R.string.newOglasna); 
          updateComplete.when = System.currentTimeMillis(); 
          Intent notificationIntent = new Intent(context, 
            OglasnaTabla.class); 
          PendingIntent contentIntent = PendingIntent 
            .getActivity(context, 0, 
              notificationIntent, 0); 

          String contentTitle = context.getText(
            R.string.newOglasna).toString(); 
          String contentText; 
          contentText = vesti.toString(); 
          updateComplete.setLatestEventInfo(context, 
            contentTitle, contentText, contentIntent); 

          notificationManager.notify(NOVA_OGLASNA, 
            updateComplete); 

          sleep(60 * 60 * 24); 

         } 
        } catch (InterruptedException e) { 
         // TODO Auto-generated catch block 
         e.printStackTrace(); 
        } 
       } 
      } 
     }; 
     t.start(); 
    } 

    @Override 
    public void onDestroy() { 
     super.onDestroy(); 
    } 

    // title for both 
    public String readRss(String feedLink) { 

     try { 
      URL url = new URL(feedLink); 

      XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); 
      factory.setNamespaceAware(false); 
      XmlPullParser xpp = factory.newPullParser(); 

      // We will get the XML from an input stream 
      xpp.setInput(getInputStream(url), "UTF_8"); 

      boolean insideItem = false; 

      // Returns the type of current event: START_TAG, END_TAG, etc.. 
      int eventType = xpp.getEventType(); 
      while (eventType != XmlPullParser.END_DOCUMENT) { 
       if (eventType == XmlPullParser.START_TAG) { 

        if (xpp.getName().equalsIgnoreCase("item")) { 
         insideItem = true; 
        } else if (xpp.getName().equalsIgnoreCase("title")) { 
         if (insideItem) 
          titles.add(xpp.nextText()); 
         // headlines.add(xpp.nextText()); // extract the 
        } 
       } else if (eventType == XmlPullParser.END_TAG 
         && xpp.getName().equalsIgnoreCase("item")) { 
        insideItem = false; 
       } 

       eventType = xpp.next(); // move to next element 
      } 

     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (XmlPullParserException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
     return titles.get(0); 
    } 

    public InputStream getInputStream(URL url) { 
     try { 
      return url.openConnection().getInputStream(); 
     } catch (IOException e) { 
      return null; 
     } 
    } 

    private String getPrefs(String category) { 
     SharedPreferences preferences = PreferenceManager 
       .getDefaultSharedPreferences(this); 
     String pref = preferences.getString(category, ""); 
     return pref; 
    } 

} 

但是，當我嘗試在DDMS運行此我得到以下日誌：

03-01 14:46:26.913: E/AndroidRuntime(3308): FATAL EXCEPTION: Thread-387 
03-01 14:46:26.913: E/AndroidRuntime(3308): java.lang.NullPointerException 
03-01 14:46:26.913: E/AndroidRuntime(3308):  at com.finki.darko.mk.services.SimpleService.readRss(SimpleService.java:146) 
03-01 14:46:26.913: E/AndroidRuntime(3308):  at com.finki.darko.mk.services.SimpleService$1.run(SimpleService.java:47) 

有誰有一個想法如何解決這個問題？

Answer 1

好的，在Android上，您的設計很不幸很糟糕。不要創建線程並在24小時內睡眠。例如，很可能您的應用在此期間會被系統殺死，爲其他更重要的應用騰出空間（如前臺的應用）。有多種方式可以讓您的應用程序定期喚醒。一種可能性是AlarmManager。

看到這個答案做什麼每隔一小時：

How to get my app to do something every hour