來自AsyncTask類的服務的Android通知

我有一個服務運行後臺並使用BroadcastReceiver和AlarmManager檢查每天的網頁排名，如果發生任何更改通知用戶。所以基本上在一個服務我運行asynctask類和檢查網址pagerank並給用戶通知。來自AsyncTask類的服務的Android通知

下面是代碼：

public class PagerankCheck extends AsyncTask<String, Integer, Integer>{ 
    private android.content.Context servicecontext; 
    private String uri = ""; 

public PagerankCheck(android.content.Context context, String url) { 
     servicecontext = context; 
     uri = url; 
    } 

protected void onProgressUpdate(Integer... progress) { 
    int icon = R.drawable.ic_launcher; 
    CharSequence ticker = uri + " pagerank changed from " + oldPR + " to " + progress[0].toString(); 
    long showAt = System.currentTimeMillis(); 
    CharSequence notificationTitle = "Notification:"; 
    CharSequence notificationMessage = "Test."; 
    final int notificationIdentifier = 101; 
    NotificationManager notificationManager2 = 
    (NotificationManager) getSystemService(android.content.Context.NOTIFICATION_SERVICE); 
    Notification notification2 = new Notification(icon, ticker, showAt); 
    android.content.Intent intent = new android.content.Intent(); 
    PendingIntent pendingIntent2 = PendingIntent.getActivity(servicecontext, 0, intent, 0); 
    notification2.setLatestEventInfo(servicecontext, notificationTitle, notificationMessage, pendingIntent2); 
    notificationManager2.notify(notificationIdentifier, notification2); 
}

在最後一行代碼的執行給出下面就logcat的錯誤。

11-01 07:14:26.488: E/AndroidRuntime(851): FATAL EXCEPTION: main 
11-01 07:14:26.488: E/AndroidRuntime(851): java.lang.NullPointerException 
11-01 07:14:26.488: E/AndroidRuntime(851): at org.siteprice.googlepagerankchecker.PagerankCheck.onProgressUpdate(PagerankCheck.java:147) 
11-01 07:14:26.488: E/AndroidRuntime(851): at org.siteprice.googlepagerankchecker.PagerankCheck.onProgressUpdate(PagerankCheck.java:1) 
11-01 07:14:26.488: E/AndroidRuntime(851): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:647) 
11-01 07:14:26.488: E/AndroidRuntime(851): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-01 07:14:26.488: E/AndroidRuntime(851): at android.os.Looper.loop(Looper.java:137) 
11-01 07:14:26.488: E/AndroidRuntime(851): at android.app.ActivityThread.main(ActivityThread.java:5103) 
11-01 07:14:26.488: E/AndroidRuntime(851): at java.lang.reflect.Method.invokeNative(Native Method) 
11-01 07:14:26.488: E/AndroidRuntime(851): at java.lang.reflect.Method.invoke(Method.java:525) 
11-01 07:14:26.488: E/AndroidRuntime(851): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
11-01 07:14:26.488: E/AndroidRuntime(851): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
11-01 07:14:26.488: E/AndroidRuntime(851): at dalvik.system.NativeStart.main(Native Method)

任何人都可以幫助我解決這個錯誤。感謝

來源

2013-11-01 sa_

是什麼線147？ 'notificationManager2'爲空？ – Raghunandan

147行是notificationManager2.notify（notificationIdentifier，notification2）; –

'NullPointerException'是最簡單的異常，你可以找出原因。只需逐行調試即可。 'progress'可能爲空，您可以調用'progress [0]'... –

使用下面

NotificationManager notificationManager2 = 
(NotificationManager) servicecontext.getSystemService(android.content.Context.NOTIFICATION_SERVICE);

來源

2013-11-01 11:24:15 Raghunandan

非常感謝這是解決方案。 –

來自AsyncTask類的服務的Android通知

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