对于无法在AsyncTask内未为ProgressDialog调用Looper.prepare感兴趣的读者，本文将会是一篇不错的选择，我们将详细介绍的线程内创建处理程序，并为您提供关于android–
对于无法在AsyncTask内未为ProgressDialog调用Looper.prepare感兴趣的读者，本文将会是一篇不错的选择，我们将详细介绍的线程内创建处理程序，并为您提供关于android – AsyncTask onPreExecute progressdialog、android – AsyncTask与ProgressDialog vs方向更改、android – AsyncTask没有显示ProgressDialog、android – java.lang.RuntimeException：无法在未调用Looper.prepare()的线程内创建处理程序的有用信息。
本文目录一览：- 无法在AsyncTask内未为ProgressDialog调用Looper.prepare（）的线程内创建处理程序
- android – AsyncTask onPreExecute progressdialog
- android – AsyncTask与ProgressDialog vs方向更改
- android – AsyncTask没有显示ProgressDialog
- android – java.lang.RuntimeException：无法在未调用Looper.prepare()的线程内创建处理程序
无法在AsyncTask内未为ProgressDialog调用Looper.prepare（）的线程内创建处理程序
我不明白为什么会收到此错误。我正在使用AsyncTask在后台运行一些进程。
我有：
protected void onPreExecute() { connectionProgressDialog = new ProgressDialog(SetPreference.this); connectionProgressDialog.setCancelable(true); connectionProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER); connectionProgressDialog.setMessage("Connecting to site..."); connectionProgressDialog.show(); downloadSpinnerProgressDialog = new ProgressDialog(SetPreference.this); downloadSpinnerProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER); downloadSpinnerProgressDialog.setMessage("Downloading wallpaper...");}当我doInBackground()根据情况进入时：
[...] connectionProgressDialog.dismiss();downloadSpinnerProgressDialog.show();[...]每当我尝试downloadSpinnerProgressDialog.show()我都会收到错误消息。
有想法吗？
答案1
小编典典该方法show()必须从被调用用户界面（UI）螺纹，而doInBackground()在不同的螺纹，其是主要的原因，运行AsyncTask被设计。
你必须调用show()无论是在onProgressUpdate()或onPostExecute()。
例如：
class ExampleTask extends AsyncTask<String, String, String> { // Your onPreExecute method. @Override protected String doInBackground(String... params) { // Your code. if (condition_is_true) { this.publishProgress("Show the dialog"); } return "Result"; } @Override protected void onProgressUpdate(String... values) { super.onProgressUpdate(values); connectionProgressDialog.dismiss(); downloadSpinnerProgressDialog.show(); }}
android – AsyncTask onPreExecute progressdialog
当onPreExecute函数执行时,我有一个AsyncTask,它给了我一个例外
** java.lang.IllegalStateException: View
com.android.internal.policy.impl.PhoneWindow$DecorView@44ea0e20
has already been added to the window
manager.**
当progressDialog的show()方法被调用时.
我的活动
public class TopNewsActivity extends ListActivity {
public static final String LOG_TAG = "Infra";
private ProgressDialog progressDialog;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
new BackgroundAsyncTask().execute();
}
public class BackgroundAsyncTask extends AsyncTask<String,Integer,ArrayList<HashMap<String,String>>> {
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(TopNewsActivity.this);
progressDialog.setCancelable(true);
progressDialog.setMessage("Loading...");
progressDialog.setProgressstyle(ProgressDialog.STYLE_SPINNER);
progressDialog.setProgress(0);
progressDialog.show();
}
@Override
protected ArrayList<HashMap<String,String>> doInBackground(String... paths) {
ArrayList<HashMap<String,String>> mylist = new ArrayList<HashMap<String,String>>();
String xml = XMLfunctions.getTopNewsXML();
Document doc = XMLfunctions.XMLfromString(xml);
int numResults = XMLfunctions.numResults(doc);
Log.d(LOG_TAG,"Number of Results: " + numResults);
if ((numResults <= 0)) {
Toast.makeText(TopNewsActivity.this,"No Result Found",Toast.LENGTH_LONG).show();
finish();
}
NodeList nodes = doc.getElementsByTagName("result");
for (int i = 0; i < nodes.getLength(); i++) {
HashMap<String,String> map = new HashMap<String,String>();
Element e = (Element) nodes.item(i);
map.put("id",XMLfunctions.getValue(e,"id"));
map.put("title","title"));
mylist.add(map);
}
return mylist;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
protected void onPostExecute(ArrayList<HashMap<String,String>> result) {
listadapter adapter = new SimpleAdapter(TopNewsActivity.this,result,R.layout.list_item,new String[] { "title" },new int[] { R.id.item_title });
setlistadapter(adapter);
progressDialog.dismiss();
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setonItemClickListener(new OnItemClickListener() {
@SuppressWarnings("unchecked")
@Override
public void onItemClick(AdapterView<?> a,View view,final int position,long id) {
HashMap<String,String> o = (HashMap<String,String>) lv.getItemAtPosition(position);
Intent i = new Intent(TopNewsActivity.this,NewsDetails.class);
i.putExtra("content_id",o.get("id"));
i.putExtra("title",o.get("title"));
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
View v = TopNewsGroup.group.getLocalActivityManager().startActivity("ShowNews",i).getDecorView();
// Again,replace the view
TopNewsGroup.group.setContentView(v);
}
});
}
}
public class MySimpleAdapter extends SimpleAdapter {
public MySimpleAdapter(Context context,List<? extends Map<String,?>> data,int resource,String[] from,int[] to) {
super(context,data,resource,from,to);
// Todo Auto-generated constructor stub
}
}
}
请帮忙！！！！！
解决方法
progressdialogs和contexts有一个常见的问题,它一直发生在我身上,并且在这个问题上有一个关于android doc的部分.当上下文实际上是您的java类的名称后跟“.this”时,您可能已使用“this”的上下文声明它.
dialog = ProgressDialog.show(Example.this,"","Doing stuff. Please wait...",true);
这是因为您希望progressDialog在主类中显示,而不是在Async类中显示.
如果这不能解决问题,您需要发布代码.
android – AsyncTask与ProgressDialog vs方向更改
经过几个绝望的日子,我终于创造了几乎成功的榜样.
目标：在onCreate中我想在AsyncTask中下载和解析XML文件,显示进度对话框,更新UI并关闭对话框.
问题：当方向更改时,Activity重新启动,AsyncTask失去对它的引用.关于它有很多问题和博客.但我无法找出为什么这个特定的解决方案不起作用.或者在这种情况下android如何处理对话框.
状态：当我启动应用程序时一切正常.我可以旋转设备,我可以通过菜单再次手动启动任务.但是在任务完成后我再次更改方向对话框弹出(如预期的那样)并且没有其他任何事情发生.没有进度改变,没有对话解雇. AsyncTask正常完成.
代码：
package com.test;
import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.util.*;
public class Test extends tabactivity {
DownloadFileAsync task;
ProgressDialog progressDialog;
static final int PROGRESS_DIALOG = 0;
private static Data data;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/* - Run from different locations bug - */
//http://code.google.com/p/android/issues/detail?id=2373
if (!isTaskRoot()) {
final Intent intent = getIntent();
final String intentAction = intent.getAction();
if (intent.hasCategory(Intent.CATEGORY_LAUNCHER) &&
intentAction != null && intentAction.equals(Intent.ACTION_MAIN)) {
finish();
}
}
/* - /Run from different locations bug */
/* -------------- Tabs ---------------- */
Resources res = getResources();
TabHost mTabHost = getTabHost();
mTabHost.addTab(mTabHost.newTabSpec("overview").setIndicator("MYTAB1",res.getDrawable(R.drawable.ic_tab_home)).setContent(R.id.tab1));
mTabHost.setCurrentTab(0);
/* -------------- /Tabs --------------- */
/* -------------- /Data --------------- */
task = (DownloadFileAsync)getLastNonConfigurationInstance();
if(task!= null) {
task.setActivity(this);
} else {
if(data == null) {
File datafile = this.getFileStreamPath("data.dat");
if(datafile.exists()){
//Log.d("log","File exists!");
try {
long time = System.currentTimeMillis();
ObjectInputStream obj = new ObjectInputStream(new FileInputStream(datafile));
data = (Data)obj.readobject();
obj.close();
Log.d("time","loaded in:"+(System.currentTimeMillis()- time));
if(data.isUpToDate() || !isOnline()){
update();
}
} catch (Exception e) {
e.printstacktrace();
datafile.delete();
data = null;
}
//Log.d("log","Passed?");
}
}
/* DEBUG if(data == null || !data.isUpToDate())*/ this.synchronize();
}
/* -------------- /Data --------------- */
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
menu.add("Synchronize").setIcon(R.drawable.ic_menu_refresh);
return true;
}
@Override
public boolean onoptionsItemSelected(MenuItem item) {
synchronize();
return super.onoptionsItemSelected(item);
}
@Override
public Object onRetainNonConfigurationInstance() {
if(task != null) task.setActivity(null);
return(task);
}
protected Dialog onCreateDialog(int id) {
switch (id) {
case PROGRESS_DIALOG:
progressDialog = new ProgressDialog(this);
progressDialog.setMessage("Aktualizuji ...");
progressDialog.setProgressstyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setCancelable(false);
//progressDialog.show();
return progressDialog;
default:
return null;
}
}
public void update() {
}
private void onTaskCompleted() {
task = null;
dismissDialog(PROGRESS_DIALOG);
Log.d("tok","Task.onComplete");
update();
}
public void synchronize(){
if(isOnline()) {
showDialog(PROGRESS_DIALOG);
progressDialog.setProgress(0); // <-- this is the last time progressDialog updates
task = new DownloadFileAsync(this);
task.execute();
}
}
public boolean isOnline() {
ConnectivityManager cm =
(ConnectivityManager) getSystemService(waspActivity.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if (netInfo != null && netInfo.isConnectedOrConnecting()) {
return true;
}
return false;
}
private static class DownloadFileAsync extends AsyncTask<String,String,String> {
private Data tempData;
private Test activity;
private int progress = 0;
private File Metafile;
private File tempDir;
private FileOutputStream fos;
public DownloadFileAsync(Test activity) {
this.setActivity(activity);
... some more init ...
}
public void setActivity(Test activity) {
this.activity = activity;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
tempData = new Data();
}
@Override
protected String doInBackground(String... aurl) {
try {
... some heavy load ...
//this.progress = someValue;
} catch (Exception e) {
Log.d("Error","Error while processing files. Code:"+e.getMessage());
e.printstacktrace();
}
//Log.d("time","Task "+(System.currentTimeMillis() - time));
return null;
}
protected void onProgressUpdate(String... progress) {
if(activity != null) activity.progressDialog.setProgress(this.progress);
}
@Override
protected void onPostExecute(String unused) {
data = tempData;
tempData = null;
if(activity != null) {
activity.onTaskCompleted();
activity = null;
}
}
}
}
解决方法
昨天,我写了一个
blog post,它描述了使用保留的片段处理配置更改.
TL; DR是在Fragment中使用你的AsyncTask托管,在Fragment上调用setRetainInstance(true),并通过保留的Fragment将AsyncTask的进度/结果报告给它的Activity.
android – AsyncTask没有显示ProgressDialog
我正在使用AsyncTask(我在我的主要活动中开始)来加载一些数据：
Context context = VehicleTabView.this;
ProgressDialog progressDialog = new ProgressDialog(context);
progressDialog.setMessage("Loading...");
new LoadingVehicles(context,progressDialog).execute(null,null,null);
这是Asyncclass：
package com.example.schedule_vehicles;
import com.example.utils.VehicleNames;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
// Showing a ProgressDialog once loading the list of vehicles is completed using an AsyncTask
public class LoadingVehicles extends AsyncTask<Void,Void,Void> {
Context context;
ProgressDialog progressDialog;
public LoadingVehicles(Context context,ProgressDialog progressDialog) {
this.context = context;
this.progressDialog = progressDialog;
}
@Override
protected void onPreExecute() {
progressDialog.show();
}
@Override
protected Void doInBackground(Void... params) {
new VehicleNames(context);
return null;
}
@Override
protected void onPostExecute(Void result) {
progressDialog.dismiss();
}
}
ProgressDialog未在屏幕上显示的问题.
我输入Log.d,看看程序是否经历了所有阶段 – onPreExecute,doInBackground,onPostExecute,它正在经历所有阶段并完成我需要的工作.但是ProgressDialog没有显示出来.我读了很多关于这个东西的信息,似乎PRE和POST执行是由主线程启动的,它被DOINBACKGROUND方法阻塞,这就是没有看到ProgressDialog的原因.我试图找到一些答案如何解决 – 但没有成功.
如果有人遇到此问题,请分享您的经验.非常感谢！
解决方法
您正在将ProgressDialog传递给Task,只是在启动AsyncTask之前show()它,而不是在AsyncTask中.
android – java.lang.RuntimeException：无法在未调用Looper.prepare()的线程内创建处理程序
嗨,我的代码有问题.我的代码是
progressD = ProgressDialog.show(MenuUtama.this,"","Uploading files to server.....",false);
Thread thread = new Thread(new Runnable(){
public void run(){
//doFileUpload();
try {
// setiap parameter yang akan dikirim melalui http
// harus encode agar
// dapat terbaca dengan baik oleh server
Cursor c = helper.getAll1(almagId);
Cursor cr = helper.getUpImage(almagId);
if(c.movetoFirst()){
//progressD = ProgressDialog.show(context,title,message)
do{
String kdstore = URLEncoder.encode(helper.getKdStore(c).toString(),"utf-8");
String nama = URLEncoder.encode(helper.getNama(c).toString(),"utf-8");
String alamat = URLEncoder.encode(helper.getAlamat(c).toString(),"utf-8");
String kdpos = URLEncoder.encode(helper.getKdPos(c).toString(),"utf-8");
String notelp = URLEncoder.encode(helper.getNotel(c).toString(),"utf-8");
String lng = URLEncoder.encode(helper.getlng(c).toString(),"utf-8");
String lat = URLEncoder.encode(helper.getLat(c).toString(),"utf-8");
String perush = URLEncoder.encode(helper.getPerus(c).toString(),"utf-8");
//String gambar = URLEncoder.encode(helper.getGamb(c).toString(),"utf-8");
//Toast.makeText(this,kdstore,Toast.LENGTH_LONG).show();
//System.out.println(gambar);
url += "?kode_toko=" + kdstore + "&&nama=" + nama + "&&alamat=" + alamat +
"&&kode_pos=" + kdpos + "&&no_telp=" + notelp + "&&longitude=" + lng + "&&latitude=" + lat +
"&&perusahaan=" + perush;
getRequest(url);
url = "http://10.234.165.232/upload_get.PHP";
}while(c.movetoNext());
}
if(cr.movetoFirst()){
do{
String kdstore = URLEncoder.encode(helper.getKdstore1(cr),"utf-8");
String gambar = URLEncoder.encode(helper.getGam1(cr),"utf-8");
url1 += "?kode_toko1=" + kdstore + "&&gambar1=" + gambar;
getRequest1(url1);
url1 = "http://10.234.165.232/upload_get2.PHP";
}while(cr.movetoNext());
}
} catch (UnsupportedEncodingException e) {
// Todo Auto-generated catch block
e.printstacktrace();
}
MenuUtama.this.runOnUiThread(new Runnable(){
public void run() {
if(progressD.isShowing())
progressD.dismiss();
}
});
}
});
thread.start();
return(true);
和这样的错误：
FATAL EXCEPTION: Thread-9
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 com.sat.alfaloc.MenuUtama.getRequest(MenuUtama.java:160)
at com.sat.alfaloc.MenuUtama$1.run(MenuUtama.java:101)
at java.lang.Thread.run(Thread.java:1096)
如果活动将数据保存到服务器我命令进度条可以运行,但如果没有这不起作用..我应该怎么做才能解决这个问题？
解决方法
由于您正在使用活动上下文的线程,您可能会收到错误.
您应该使用AsyncTask而不是普通线程.
在AsyncTask中,有一个onPreExecute()和onPostExecute()方法,它们在主线程上执行,并且有一个方法doInBackground()将在后台执行,以便您可以轻松实现长期进程.
你可以参考this example
关于无法在AsyncTask内未为ProgressDialog调用Looper.prepare和的线程内创建处理程序的问题我们已经讲解完毕，感谢您的阅读，如果还想了解更多关于android – AsyncTask onPreExecute progressdialog、android – AsyncTask与ProgressDialog vs方向更改、android – AsyncTask没有显示ProgressDialog、android – java.lang.RuntimeException：无法在未调用Looper.prepare()的线程内创建处理程序等相关内容，可以在本站寻找。
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