从片段的onCreateView调用AsyncTask方法失败 [英] call to AsyncTask method from fragment's onCreateView, fails
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问题描述
我一直在尝试实现片段布局,并且在其中一个片段类中,我正在使用asynctask. 到目前为止,我无法从片段的oncreateView调用asynctask方法. 当我运行该应用程序时,出现提示错误不幸的是,该应用程序已停止"
I have been trying to implement fragment layout and in one of the fragment classes i am using asynctask. so far I am unable to call the asynctask method from fragment's oncreateView. when i run the app its giving error 'unfortunately the app has stopped'
这是我片段的代码
package com.example.mohamed.myapplication;
import java.io.File;
import java.io.IOException;
import org.jsoup.Connection;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Attributes;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import android.app.ActionBar;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v13.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ListView;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class FirstFragment extends Fragment {
// URL Address
String url = "http://www.androidbegin.com";
ProgressDialog mProgressDialog;
AsyncTask aTask;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
new Title().execute();
View rootView = inflater.inflate(R.layout.first_frag, container, false);
return rootView;
}
// Title AsyncTask
private class Title extends AsyncTask<Void, Void, Void> {
String title;
// Context mcontext;
// public Title(Context c){
// mcontext=c;
// }
@Override
protected void onPreExecute() {
super.onPreExecute();
// mProgressDialog = new ProgressDialog(mcontext);
// mProgressDialog.setTitle("Android Basic JSoup Tutorial");
// mProgressDialog.setMessage("Loading...");
// mProgressDialog.setIndeterminate(false);
// mProgressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
try {
// Connect to the web site
Document document = Jsoup.connect(url).get();
// Get the html document title
title = document.title();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// Set title into TextView
TextView txttitle = (TextView) getView().findViewById(R.id.First);
txttitle.setText(title);
mProgressDialog.dismiss();
}
}
public static FirstFragment newInstance(String text) {
FirstFragment f = new FirstFragment();
Bundle b = new Bundle();
b.putString("msg", text);
f.setArguments(b);
return f;
}
}
那么,调用asynctask的正确方法是什么?
so, what is the right way to call asynctask?
这是我的日志
12-01 14:44:40.052 1093-1093/com.example.mohamed.myapplication D/dalvikvm﹕ GC_FOR_ALLOC freed 49K, 3% free 3755K/3868K, paused 2ms, total 4ms
12-01 14:44:40.056 1093-1093/com.example.mohamed.myapplication D/dalvikvm﹕ GC_FOR_ALLOC freed 3K, 3% free 3973K/4092K, paused 2ms, total 2ms
12-01 14:44:40.064 1093-1093/com.example.mohamed.myapplication I/dalvikvm-heap﹕ Grow heap (frag case) to 6.356MB for 2536932-byte allocation
12-01 14:44:40.072 1093-1103/com.example.mohamed.myapplication D/dalvikvm﹕ GC_FOR_ALLOC freed <1K, 2% free 6450K/6572K, paused 5ms, total 5ms
12-01 14:44:40.180 1093-1093/com.example.mohamed.myapplication D/libEGL﹕ loaded /system/lib/egl/libEGL_genymotion.so
12-01 14:44:40.180 1093-1093/com.example.mohamed.myapplication D/﹕ HostConnection::get() New Host Connection established 0xb8a8f1c0, tid 1093
12-01 14:44:40.184 1093-1093/com.example.mohamed.myapplication D/libEGL﹕ loaded /system/lib/egl/libGLESv1_CM_genymotion.so
12-01 14:44:40.184 1093-1093/com.example.mohamed.myapplication D/libEGL﹕ loaded /system/lib/egl/libGLESv2_genymotion.so
12-01 14:44:40.224 1093-1093/com.example.mohamed.myapplication W/EGL_genymotion﹕ eglSurfaceAttrib not implemented
12-01 14:44:40.224 1093-1093/com.example.mohamed.myapplication E/OpenGLRenderer﹕ Getting MAX_TEXTURE_SIZE from GradienCache
12-01 14:44:40.228 1093-1093/com.example.mohamed.myapplication E/OpenGLRenderer﹕ MAX_TEXTURE_SIZE: 8192
12-01 14:44:40.232 1093-1093/com.example.mohamed.myapplication E/OpenGLRenderer﹕ Getting MAX_TEXTURE_SIZE from Caches::initConstraints()
12-01 14:44:40.232 1093-1093/com.example.mohamed.myapplication E/OpenGLRenderer﹕ MAX_TEXTURE_SIZE: 8192
12-01 14:44:40.236 1093-1093/com.example.mohamed.myapplication D/OpenGLRenderer﹕ Enabling debug mode 0
推荐答案
在创建视图之前,您尝试在onCreateView
中使用AsyncTask
.
You trying to use AsyncTask
in onCreateView
before view created.
尝试在onActivityCreated
中调用AsyncTask:
Try to call AsyncTask in onActivityCreated
:
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
new Title().execute();
}
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