我想在android上使用AsyncTask類,但我有一個問題。不能在線程中創建處理程序沒有調用與AsyncTask Looper.prepare()
這裏是我的代碼:
public void CheckIfUserIsLogedIn()
{
int userPresence = localDatabase.CheckUserPresence();
if (userPresence == 0)
{
setContentView(R.layout.main);
new checkCountryAsync().execute();
}
else
{
setContentView(R.layout.userlogedon);
}
}
class checkCountryAsync extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(String... aurl) {
int countryPresence = localDatabase.CheckCountryPresence();
if (countryPresence == 0)
{
CountryTable country = new CountryTable() ;
country.EnterCountry();
}
return null;
}
}
我不知道我做錯了什麼。 LocalDatabase類中的CheckCountryPresence()方法只進行查詢並返回結果。
謝謝。
編輯:這裏是logcat的:
02-20 08:41:25.804: W/dalvikvm(26458): threadid=10: thread exiting with uncaught exception (group=0x4001d5a0)
02-20 08:41:25.834: E/AndroidRuntime(26458): FATAL EXCEPTION: AsyncTask #1
02-20 08:41:25.834: E/AndroidRuntime(26458): java.lang.RuntimeException: An error occured while executing doInBackground()
02-20 08:41:25.834: E/AndroidRuntime(26458): at android.os.AsyncTask$3.done(AsyncTask.java:200)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.lang.Thread.run(Thread.java:1027)
02-20 08:41:25.834: E/AndroidRuntime(26458): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
02-20 08:41:25.834: E/AndroidRuntime(26458): at android.os.Handler.<init>(Handler.java:121)
02-20 08:41:25.834: E/AndroidRuntime(26458): at android.app.Activity.<init>(Activity.java:717)
02-20 08:41:25.834: E/AndroidRuntime(26458): at milos.mdpi.CountryTable.<init>(CountryTable.java:5)
02-20 08:41:25.834: E/AndroidRuntime(26458): at milos.mdpi.MDPIActivity$checkCountryAsync.doInBackground(MDPIActivity.java:367)
02-20 08:41:25.834: E/AndroidRuntime(26458): at milos.mdpi.MDPIActivity$checkCountryAsync.doInBackground(MDPIActivity.java:1)
02-20 08:41:25.834: E/AndroidRuntime(26458): at android.os.AsyncTask$2.call(AsyncTask.java:185)
02-20 08:41:25.834: E/AndroidRuntime(26458): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
02-20 08:41:25.834: E/AndroidRuntime(26458): ... 4 more
在我看來問題是在國家表的第5行,而不是在AsyncTask! – 2012-02-20 08:16:33