有时我在我的应用中遇到此崩溃错误
java.lang.RuntimeException: An error occured while executing doInBackground()
这是完整的logCat:
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:200)
at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
at java.lang.Thread.run(Thread.java:1019)
Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:121)
at android.widget.Toast.<init>(Toast.java:68)
at android.widget.Toast.makeText(Toast.java:231)
at kostas.menu.olympiakos.nea.loadFeed(nea.java:84)
at kostas.menu.olympiakos.nea.access$1(nea.java:75)
at kostas.menu.olympiakos.nea$BackgroundAsyncTask_nea.doInBackground(nea.java:242)
at kostas.menu.olympiakos.nea$BackgroundAsyncTask_nea.doInBackground(nea.java:1)
at android.os.AsyncTask$2.call(AsyncTask.java:185)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
... 4 more
这是我的.nea类代码:
package kostas.menu.olympiakos;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import android.app.Dialog;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationSet;
import android.view.animation.LayoutAnimationController;
import android.view.animation.TranslateAnimation;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class nea extends ListActivity{
private List<Message> messages;
List<String> des = new ArrayList<String>();//to prosthesa gia na anoigei to keimeno sto alert
List<String> text = new ArrayList<String>();//to prosthesa gia na anoigei o titlos sto alert
List<URL> url = new ArrayList<URL>();//to prosthesa gia to koumpi pou pigainei sto link
List<String> imgl = new ArrayList<String>();//to prosthesa gia na anoigei to keimeno sto alert
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main2);
if(isInternetOn()) {
new BackgroundAsyncTask_nea().execute();
}else{
Toast.makeText(nea.this,R.string.no_connection, Toast.LENGTH_SHORT).show();
finish();
}
}
private void loadFeed(AsyncTask<Void, Void, Void> asyncTask){
try{
BaseFeedParser parser = new BaseFeedParser();
messages = parser.parse();
}
catch (Throwable t){
Log.e("OSFP.News",t.getMessage(),t);
Toast.makeText(nea.this, "Χρειάζεστε σύνδεση στο internet",
Toast.LENGTH_SHORT).show();
finish();
}
}
private void displayRss(){
ArrayList<HashMap<String, String>> List_nea = new ArrayList<HashMap<String, String>>(messages.size());
for (Message msg : messages){
des.add(msg.getDescription());// keimeno
text.add(msg.getTitle());// titlos
url.add(msg.getLink());// link
imgl.add(msg.getImgLink());
HashMap<String, String> map = new HashMap<String, String>();
map.put("name", msg.getTitle());
map.put("date", msg.getDate());
List_nea.add(map);
ListAdapter mSchedule = new SimpleAdapter(this, List_nea, R.layout.row,
new String[] {"name", "date"}, new int[] {R.id.TextView01, R.id.TextView02});
this.setListAdapter(mSchedule);
}
AnimationSet set = new AnimationSet(true);
Animation animation = new AlphaAnimation(0.0f, 1.0f);
animation.setDuration(400);
set.addAnimation(animation);
animation = new TranslateAnimation(
Animation.RELATIVE_TO_SELF, 0.0f,Animation.RELATIVE_TO_SELF, 0.0f,
Animation.RELATIVE_TO_SELF, -1.0f,Animation.RELATIVE_TO_SELF, 0.0f
);
animation.setDuration(400);
set.addAnimation(animation);
LayoutAnimationController controller = new LayoutAnimationController(set, 0.5f);
ListView listViewn = getListView();
listViewn.setLayoutAnimation(controller);
}
protected void onListItemClick(ListView l, View v, final int position, long id) {
super.onListItemClick(l, v, position, id);
Dialog dialog = new Dialog(this);
String description = des.get(position).toString().replaceAll("\\<.*?>","");
String imagee=imgl.get(position).toString();
final URL link = url.get(position);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.single);
dialog.setCancelable(true);
Toast msg = Toast.makeText(nea.this, "The url is : "+imagee, Toast.LENGTH_LONG);
msg.show();
//xrisimopoiisa toast gia na elegxw poio link pernw apo to site
TextView title_dialog = (TextView) dialog.findViewById(R.id.title_dialog);
title_dialog.setText(text.get(position));
TextView text = (TextView) dialog.findViewById(R.id.descr);
text.setText(description);
ImageView image1 = (ImageView) dialog.findViewById(R.id.image1);
try {
//where imageUrl is what you pulled out from the rss feed
Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(imagee).getContent());
image1.setImageBitmap(bitmap);
} catch (MalformedURLException e) {
//log exception here
} catch (IOException e) {
//log exception here
}
Button btnt = (Button) dialog.findViewById(R.id.btnrss);//ti kanei to koumpi otan to patas gia to link
btnt.setOnClickListener(new View.OnClickListener() {
public void onClick (View view) {
Intent viewMessage = new Intent(Intent.ACTION_VIEW, Uri.parse(link.toExternalForm()));
startActivityForResult(viewMessage, 0);
}
});
dialog.show();
}
//options menu
@Override
public boolean onCreateOptionsMenu(Menu menu2) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu2, menu2);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.refresh:
new BackgroundAsyncTask_nea().execute();
break;
}
return true;
}
public class BackgroundAsyncTask_nea extends
AsyncTask<Void, Void, Void> {
private ProgressDialog dialog;
int myProgress;
@Override
protected void onPostExecute(Void result) {
displayRss();
dialog.dismiss();
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
dialog = ProgressDialog.show(nea.this, "", "Loading. Please wait...", true);
myProgress = 0;
}
protected void onProgressUpdate(Integer... progress) {
// TODO Auto-generated method stub
//super.onProgressUpdate(values);
dialog.setProgress(progress[0]);
}
@Override
protected Void doInBackground(Void... arg0) {
// TODO Auto-generated method stub
loadFeed(this);
return null;
}
}
public final boolean isInternetOn() {
ConnectivityManager connec = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
// ARE WE CONNECTED TO THE NET
if ( connec.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTED ||
connec.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTING ||
connec.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTING ||
connec.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTED ) {
// MESSAGE TO SCREEN FOR TESTING (IF REQ)
//Toast.makeText(this, connectionType + ” connected”, Toast.LENGTH_SHORT).show();
return true;
} else if ( connec.getNetworkInfo(0).getState() == NetworkInfo.State.DISCONNECTED || connec.getNetworkInfo(1).getState() == NetworkInfo.State.DISCONNECTED ) {
//System.out.println(“Not Connected”);
return false;
}
return false;
}
}
为什么我会收到此错误?我该如何解决?谢谢:)
编辑:
Public void toast_doInBck(View view) {
// Do something long
Runnable runnable = new Runnable() {
@Override
public void run() {
for (int i = 0; i <= 10; i++) {
Toast.makeText(nea.this,R.string.no_connection, Toast.LENGTH_SHORT).show();
handler.post(new Runnable() {
@Override
public void run() {
}
});
}
}
};
new Thread(runnable).start();
}
EDIT2:
private void loadFeed(AsyncTask<Void, Void, Void> asyncTask){
try{
BaseFeedParser parser = new BaseFeedParser();
messages = parser.parse();
}
catch (Throwable t){
Log.e("OSFP.News",t.getMessage(),t);
Looper.prepare();
Toast.makeText(nea.this, "Παρακαλώ προσπαθήστε αργότερα..",
Toast.LENGTH_SHORT).show();
finish();
Looper.loop();
}
}
答案 0 :(得分:26)
这可能是因为你试图在doInBackground()上显示一些东西。 doInBackground在一个工作线程中运行,该线程无法进行任何UI工作(包括显示Toasts,这就是你正在做的事情)。相反,所有UI工作都应该在onPostExecute()上完成。
答案 1 :(得分:6)
您无法在后台线程上执行任何GUI工作。相反,你应该post a Runnable to a handler created in the GUI thread使你的Toast在正确的线程上执行。
编辑:由于删除了家庭作业标签,我将概述如何做到这一点;有关完整示例,请参阅this article。
答案 2 :(得分:1)
您在Toast
中显示loadFeed
,doInBackground
在AsyncTask
部分{{1}}中显示。您不应该从那里访问UI。
答案 3 :(得分:1)
我认为在此代码中Toast
会为您带来问题,
catch (Throwable t){
Log.e("OSFP.News",t.getMessage(),t);
Toast.makeText(nea.this, "Χρειάζεστε σύνδεση στο internet",
Toast.LENGTH_SHORT).show();
finish();
}
因为你试图从UI operation
的工作线程做AsyncTask
,所以这绝不允许..
更新:如果您要更新doInBackGround()
AsyncTask
使用publishProgress(Progress...)
和onProgressUpdate(Progress...)
的内容。