[英]Android AsyncTask crashing
嗨,我有AsyncTask的問題,即時通訊從網絡上解析了一些數據,但是當我想使用此類時,我的應用程序崩潰了:
10-31 12:29:29.941: E/AndroidRuntime(3741): FATAL EXCEPTION: AsyncTask #2
10-31 12:29:29.941: E/AndroidRuntime(3741): java.lang.RuntimeException: An error occured while executing doInBackground()
10-31 12:29:29.941: E/AndroidRuntime(3741): at android.os.AsyncTask$3.done(AsyncTask.java:299)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
10-31 12:29:29.941: E/AndroidRuntime(3741): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.lang.Thread.run(Thread.java:856)
10-31 12:29:29.941: E/AndroidRuntime(3741): Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.ArrayList.get(ArrayList.java:304)
10-31 12:29:29.941: E/AndroidRuntime(3741): at morisson.Notowaniagieldowe.MainActivity$Cena.doInBackground(MainActivity.java:169)
10-31 12:29:29.941: E/AndroidRuntime(3741): at morisson.Notowaniagieldowe.MainActivity$Cena.doInBackground(MainActivity.java:1)
10-31 12:29:29.941: E/AndroidRuntime(3741): at android.os.AsyncTask$2.call(AsyncTask.java:287)
10-31 12:29:29.941: E/AndroidRuntime(3741): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
10-31 12:29:29.941: E/AndroidRuntime(3741): ... 5 more
和代碼是:
public class Cena extends AsyncTask<Integer,Void,String>{
ProgressDialog dialog;
@Override
protected String doInBackground(Integer... params) {
int a = params[0];
try {
Document doc = Jsoup.connect("http://www.money.pl/gielda/gpw/akcje/").get();
Elements elements = doc.select("td.ar");
System.out.println("test2:" + elements.get(a).text());
return elements.get(a).text();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
我也使用AsyncTask的其他2類,但我沒有任何問題。 我嘗試打印“ test2”時會出現崩潰,當然,當我嘗試返回值時也會出現崩潰。 有什么建議么?
如果仔細檢查錯誤日志,您會發現這里的實際錯誤是ArrayIndexOutOfBound
異常。 含義elements.get(a)
或int a = params[0];
可能返回null。
由於尚未捕獲到異常(這導致了崩潰),因此我高度懷疑int a = params[0];
成為問題的原因,因為它是try catch
塊中沒有的唯一代碼。
try {
Document doc = Joup.connect("http://www.money.pl/gielda/gpw/akcje/").get();
Elements elements = doc.select("td.ar");
if(elemetns!=null&&a!=null){
System.out.println("test2:" + elements.get(a).text());
return elements.get(a).text();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
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