问题
I have been trying to create time out while AsyncTask execution more than 1 minute. If the time up, then should exit with Notification.
This is my code:
private class GetLongLat extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
longlatDialog = new ProgressDialog(MainActivity.this);
longlatDialog.setMessage("Fetching Data. Please wait..");
longlatDialog.setCancelable(false);
longlatDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
GPSTracker gpsTracker;
//This is the timer to set time out
Timer timer = new Timer();
timer.schedule(new TaskKiller(this), 3000);
timer.cancel();
do{
gpsTracker = new GPSTracker(MainActivity.this);
gpsTracker.getLocation();
}while(!String.valueOf(gpsTracker.latitude).equals("0.0"));
return null;
}
protected void onCancelled() {
// do something, inform user etc.
Toast.makeText(getApplicationContext(), "Failed getting long lat. Please check your internet connection", Toast.LENGTH_LONG).show();
System.exit(1);
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (longlatDialog.isShowing())
longlatDialog.dismiss();
}
}
And this is a class called in doInBackground to set the time up.
class TaskKiller extends TimerTask {
private AsyncTask<?, ?, ?> mTask;
public TaskKiller(AsyncTask<?, ?, ?> task) {
this.mTask = task;
}
public void run() {
mTask.cancel(true);
}
}
But when i run the code, nothing happen. I mean the progress dialog always run very long time.
EDIT I have edit my code to call GetLongLat something like this:
GetLongLat n = new GetLongLat();
n.execute();
try {
n.get(3000, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TimeoutException e) {
// TODO Auto-generated catch block
Toast.makeText(getApplicationContext(), "Failed getting long lat. Please check your internet connection", Toast.LENGTH_LONG).show();
System.exit(1);
}
But also, doesn't work.
回答1:
I think you can use AsyncTask.get()
GetLongLat n = new GetLongLat();
n.get(30000, TimeUnit.MILLISECONDS);
you will have to use the n.get in a separate Thread..
Edited: one more different method but not efficient.,
GetLongLat n = new GetLongLat();
n.execute();
Handler handler = new Handler();
handler.postDelayed(new Runnable()
{
@Override
public void run() {
if ( n.getStatus() == AsyncTask.Status.RUNNING )
n.cancel(true);
}
}, 30000 );
回答2:
why are you canceling the timer? just after calling schedule()?
Cancels the Timer and all scheduled tasks
timer.cancel(); should be removed. check docs for cancel()
回答3:
You can achieve this behaviour in many ways.
Here's an example using CountDownTimer
// Start your AsyncTask
private YourAsyncTask mTask = new YourAsyncTask().execute();
// Run a timer after you started the AsyncTask
new CountDownTimer(60000, 1000) {
public void onTick(long millisUntilFinished) {
// Do nothing
}
public void onFinish() {
mTask.cancel(true);
}
}.start();
You are cancelling the timer just after initiating it. You can do it like this too. But this type of busy waiting is not recommended at all.
@Override
protected Void doInBackground(Void... arg0) {
GPSTracker gpsTracker;
//This is the timer to set time out
new CountDownTimer(60000, 1000) {
public void onTick(long millisUntilFinished) {
// Do nothing
}
public void onFinish() {
// Set latitude to zero to finish the while loop outside.
// gpsTracker.latitude = "0.0"; // Something like this
}
}.start();
do{
gpsTracker = new GPSTracker(MainActivity.this);
gpsTracker.getLocation();
}while(!String.valueOf(gpsTracker.latitude).equals("0.0"));
return null;
}
回答4:
Here's another approach. In your doInBackground method, you can use System.currentTimeMillis to check whether 1 minute has elapsed or not.
protected Void doInBackground(Void... arg0) {
GPSTracker gpsTracker;
long startTime = System.currentTimeMillis();
do{
gpsTracker = new GPSTracker(MainActivity.this);
gpsTracker.getLocation();
}while(!String.valueOf(gpsTracker.latitude).equals("0.0")
&& ((System.currentTimeMillis() - startTime) <= 60000);//60000 millisecond = 1 minute
return null;
}
`
回答5:
Just alter your code like this and check whether your async task is getting cancelled or not.
GetLongLat getLongLatAsync = new GetLongLat();
getLongLatAsync.execute();
try {
Handler handler = new Handler();
/** 1st method **/
handler.postDelayed(new Runnable()
{
@Override
public void run() {
if (getLongLatAsync.getStatus() == AsyncTask.Status.RUNNING )
getLongLatAsync.cancel(true);
}
}, 3000 ); //3 Seconds
/** 1st method ends **/
/** second method */
handler.post(new Runnable()
{
@Override
public void run() {
getLongLatAsync.get(3000, TimeUnit.MILLISECONDS);//You should run it in seperated thread or else it will block ui thread.
}
});
/** Second method ends**/
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TimeoutException e) {
// TODO Auto-generated catch block
Toast.makeText(getApplicationContext(), "Failed getting long lat. Please check your internet connection", Toast.LENGTH_LONG).show();
}
and in the onCancelld method write your logic
@Override
protected void onCancelled() {
Log.d(TAG,"Asynctask has been cancelled.");
}
来源：https://stackoverflow.com/questions/36245777/how-to-set-time-out-for-asynctask-execution