如何正确处理异步任务结束?
问题描述:
我使用AsyncTask从服务器获取我的应用程序需要的所有数据。这工作正常。但是,第二次重新启动应用程序时,应用程序会崩溃。如何正确处理异步任务结束?
我收到以下错误日志:
04-17 14:22:57.171: E/AndroidRuntime(956): FATAL EXCEPTION: AsyncTask #2
04-17 14:22:57.171: E/AndroidRuntime(956): java.lang.RuntimeException: An error occured while executing doInBackground()
04-17 14:22:57.171: E/AndroidRuntime(956): at android.os.AsyncTask$3.done(AsyncTask.java:278)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.lang.Thread.run(Thread.java:856)
04-17 14:22:57.171: E/AndroidRuntime(956): Caused by: java.lang.ArrayIndexOutOfBoundsException: length=14; index=14
04-17 14:22:57.171: E/AndroidRuntime(956): at flexform.ro.android.app.FlexFormActivity$getDataClass.doInBackground(FlexFormActivity.java:88)
04-17 14:22:57.171: E/AndroidRuntime(956): at flexform.ro.android.app.FlexFormActivity$getDataClass.doInBackground(FlexFormActivity.java:1)
04-17 14:22:57.171: E/AndroidRuntime(956): at android.os.AsyncTask$2.call(AsyncTask.java:264)
04-17 14:22:57.171: E/AndroidRuntime(956): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
下面你有我的AsyncTask类:
class getDataClass extends AsyncTask<String, Void, String>{
protected String doInBackground(String...urls){
String response = "";
for(String url : urls){
response = "";
descriptionArray_Counter++;
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try{
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(new InputStreamReader(content));
String s = "";
while((s = buffer.readLine()) != null){
response += s;
}
}catch(Exception e){
e.printStackTrace();
}
Resources.descriptionArray[descriptionArray_Counter] = response;
}
return response;
}
protected void onPostExecute(String result){
Toast.makeText(getApplicationContext(), "All entres have been loaded!", Toast.LENGTH_SHORT).show();
JSONArray offersJSON;
JSONArray newsJSON;
try{
newsJSON = new JSONArray(Resources.descriptionArray[9]);
if(newsJSON.length() > 20)
Resources.newsLength = 20;
else
Resources.newsLength = newsJSON.length();
for(int i = 0; i < Resources.newsLength; i++){
JSONObject tempObject = newsJSON.getJSONObject(i);
Resources.news_id[i] = tempObject.getString("id");
Resources.news_title[i] = tempObject.getString("title");
Resources.news_descriptionShort[i] = tempObject.getString("description_short");
Resources.news_descriptionLong[i] = tempObject.getString("description_long");
Resources.news_date[i] = tempObject.getString("date");
Resources.news_urgent[i] = tempObject.getString("urgent");
}
}catch(JSONException e){
e.printStackTrace();
}
try {
offersJSON = new JSONArray(Resources.descriptionArray[10]);
if(offersJSON.length() > 20)
Resources.offersLength = 20;
else
Resources.offersLength = offersJSON.length();
for(int i = 0; i < Resources.offersLength; i++){
JSONObject tempObject = offersJSON.getJSONObject(i);
Resources.offers_id[i] = tempObject.getString("id");
Resources.offers_offertant[i] = tempObject.getString("Ofertant");
Resources.offers_description[i] = tempObject.getString("Descriere");
Resources.offers_contact[i] = tempObject.getString("Contact");
Resources.offers_date[i] = tempObject.getString("Data");
Resources.offers_available[i] = tempObject.getString("Valabil");
}
Intent intent = new Intent(FlexFormActivity.this, MainMenu.class);
startActivity(intent);
}catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
我希望有人带着几分更多的经验,将能向我解释正确,正确的方式来解决这个崩溃...
欢呼和感谢谁花时间回答并帮助我...
答
我会怀疑你永远不会重置descriptionArray_Counter回0。因此,当你执行你的任务以下行
Resources.descriptionArray[descriptionArray_Counter] = response;
大概评估,以
Resources.descriptionArray[14] = response;
和你的描述阵列只长度14.你可以在你的堆栈跟踪中看到它完全告诉你这一点。
答
您正在收到arrayIndexOutOfBounds错误。你对数组的一个调用,特别是在88行,是超出界限的。异步任务不是问题。
对不起......现在觉得哑巴。一直在编码几个小时,只是错过了它。非常感谢您阅读代码并回答问题。 – Eugen 2012-04-17 14:36:49
您代码中另一个可疑的部分是您在for循环开始时增加了descriptionArray_Counter。在阵列中设置响应之后,你确定不打算这么做吗? – 2012-04-17 14:41:41