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我想要做的是使用異步任務來顯示進度對話框，而我的應用程序搜索他們的位置。在找到它們的位置後，它應該顯示一個帶有一些信息的警告對話框。但我不是100％確定如何做到這一點。這就是我在LocationChanged.java：進度對話框與異步任務問題
@Override
protected Void doInBackground(Void... params) {
final LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
geocoder = new Geocoder(context, Locale.getDefault());
final LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
// Called when a new location is found by the network location provider.
lat =location.getLatitude();
lon = location.getLongitude();
//TextView tv = (TextView) findViewById(R.id.tv3);
try{
addresses=(geocoder.getFromLocation(lat, lon, 1));
if (addresses.size() > 0) {
// String address = addresses.get(0).getAddressLine(0);
String city = addresses.get(0).getAddressLine(1);
String id = city.substring(0,city.length()-5);
String state1=String.valueOf(id.charAt(id.length()-3));
String state2=String.valueOf(id.charAt(id.length()-2));
STATE = state1+state2;
//String country = addresses.get(0).getAddressLine(2);
//tv.setText(STATE);
progressDialog.dismiss();
locationManager.removeUpdates(this);
}
else {
//tv.setText("Oops...");
}
}catch(IOException e){
e.printStackTrace();
}
}
，這是logcat的當它運行：
07-08 17:26:21.456: ERROR/AndroidRuntime(2755): FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
at java.lang.Thread.run(Thread.java:864)
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.location.LocationManager$ListenerTransport$1.<init>(LocationManager.java:209)
at android.location.LocationManager$ListenerTransport.<init>(LocationManager.java:209)
at android.location.LocationManager._requestLocationUpdates(LocationManager.java:687)
at android.location.LocationManager.requestLocationUpdates(LocationManager.java:512)
at com.nick.whatsthetip.LocationChanged.doInBackground(LocationChanged.java:121)
at com.nick.whatsthetip.LocationChanged.doInBackground(LocationChanged.java:24)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
... 5 more
07-08 17:26:21.716: ERROR/EmbeddedLogger(696): App crashed! Process: com.nick.whatsthetip
07-08 17:26:21.716: ERROR/EmbeddedLogger(696): App crashed! Package: com.nick.whatsthetip v5 (1.1.0)
07-08 17:26:21.987: ERROR/WindowManager(2755): Activity com.nick.whatsthetip.Settings has leaked window [email protected] that was originally added here
android.view.WindowLeaked: Activity com.nick.whatsthetip.Settings has leaked window [email protected] that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:468)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:419)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:351)
at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:171)
at android.view.Window$LocalWindowManager.addView(Window.java:558)
at android.app.Dialog.show(Dialog.java:282)
at android.app.ProgressDialog.show(ProgressDialog.java:116)
at android.app.ProgressDialog.show(ProgressDialog.java:99)
at android.app.ProgressDialog.show(ProgressDialog.java:94)
at com.nick.whatsthetip.LocationChanged.onPreExecute(LocationChanged.java:49)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)
at com.nick.whatsthetip.Settings$3.onClick(Settings.java:119)
at android.view.View.performClick(View.java:4102)
好吧，是不是可以從該類更新ui元素，是否必須從原始類的哪裏調用包含異步任務的類來完成？ – ez4nick
是不是它自己的類，是doInBackground方法，該方法是爲了不阻止主線程，換句話說是一個工作線程，所以你可以使用OnyncTask的onPostExecuted方法來關閉對話框，無論你在doInBackground中做什麼已完成... –