问题
i have an asyncTaskProc that read some info from a DB and write it on the ui...
the code works perfectcly on Android 4.0 but doesn't work on 2.3... here is the code
NEW ASYNCTASK
`public class IceCastPoll extends TimerTask {
public IceCastPoll() {
}
@TargetApi(9)
public void run() {
new AsyncTaskProc().execute();
}
}`
THE ASYNCTASK implementation
@TargetApi(9)
class AsyncTaskProc extends AsyncTask<Void, String, Void> {
List<Stream> streams=null;
@Override
protected void onPostExecute(Void result) {
textSong =(TextView) findViewById(R.id.textViewCurrentSong);
textArtist =(TextView) findViewById(R.id.textViewCurrentArtist);
textTit=(TextView) findViewById(R.id.textViewTit);
textArt=(TextView) findViewById(R.id.TextViewArt);
copertina=(ImageView) findViewById(R.id.imageViewCopertina);
new DownloadImageTask((ImageView) findViewById(R.id.imageViewCopertina)).execute("http://service.uniradiocesena.it/OnAir.jpg");
try {
for (Stream stream: streams) {
try
{
//Thread.sleep(5000);
//textSong.setText((stream.getCurrentSong()));
textArt.setText("Artista:");
textTit.setText("Titolo:");
StringTokenizer tokens = new StringTokenizer(stream.getCurrentSong(), "-");
String first = tokens.nextToken();
String second = tokens.nextToken();
textSong.setText(first);
textArtist.setText(second);
} catch (Exception e) {
//Thread.sleep(5000);
textSong.setText((stream.getCurrentSong()));
textArt.setText("Rotazione:");
textTit.setText("");
textArtist.setText("");
}
}
} catch (Exception e) {
//Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_SHORT).show();
}
}
@Override
protected Void doInBackground(Void... unused) {
Scraper scraper = new IceCastScraper();
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
try {
streams = scraper.scrape(new URI("http://r35798.ovh.net:8000/"));
} catch (ScrapeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
//Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_LONG).show();
} catch (URISyntaxException e) {
// TODO Auto-generated catch block
e.printStackTrace();
//Toast.makeText(getApplicationContext(),e.toString(), Toast.LENGTH_LONG).show();
}
return (null);
}
}`
THE LOGCAT ERRORS
11-07 11:09:49.729: W/dalvikvm(18983): Exception Ljava/lang/RuntimeException; thrown while initializing Landroid/os/AsyncTask;
11-07 11:09:49.729: W/dalvikvm(18983): threadid=9: thread exiting with uncaught exception (group=0x40018560)
11-07 11:09:49.739: E/AndroidRuntime(18983): FATAL EXCEPTION: Timer-0
11-07 11:09:49.739: E/AndroidRuntime(18983): java.lang.ExceptionInInitializerError
11-07 11:09:49.739: E/AndroidRuntime(18983): at com.example.appuniradiocesena.SwipeyTabsSampleActivity$IceCastPoll.run(SwipeyTabsSampleActivity.java:233)
11-07 11:09:49.739: E/AndroidRuntime(18983): at java.util.Timer$TimerImpl.run(Timer.java:284)
11-07 11:09:49.739: E/AndroidRuntime(18983): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
11-07 11:09:49.739: E/AndroidRuntime(18983): at android.os.Handler.<init>(Handler.java:121)
11-07 11:09:49.739: E/AndroidRuntime(18983): at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
11-07 11:09:49.739: E/AndroidRuntime(18983): at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
11-07 11:09:49.739: E/AndroidRuntime(18983): at android.os.AsyncTask.<clinit>(AsyncTask.java:152)
11-07 11:09:49.739: E/AndroidRuntime(18983): ... 2 more
Any suggestion it will be very very apreciated !
and sry for english mistakes :D
回答1:
You should start AsyncTask with a Handler created on main thread. So replace your run() method in IceCastPoll with this one:
private Handler handler = new Handler(Looper.getMainLooper());
@Override
public void run() {
handler.post(new Runnable() {
public void run() {
new AsyncTaskProc().execute();
}
});
}
回答2:
new AsyncTaskProc().execute();
Dont put this code inside a thread .
Because it is already a Handler.
Simple Execute the code where ever you need like new AsyncTaskProc().execute(); its enough my Friend
回答3:
One Quick suggestion in your code: Why are you doing findViewById() every time, because you are trying to execute AsyncTask at particular interval, so its not feasible way to do it every time.
Instead, find all those views inside onCreate() method.
来源：https://stackoverflow.com/questions/13267711/android-why-i-get-these-asynctask-error