Android - Stop AsyncTask when back button is pressed and return to previous Activity

问题

I've an AsyncTask and I want it to stip execution when back button is pressed. I also want the app to return to the previous displayed Activity. It seems I've managed in stop the Task but the app doesn't return to the previous activity. Any ideas? This is an extract from my code

private class MyTask extends AsyncTask<Void, Void, Void> implements OnDismissListener{
    private boolean exception= false;

    @Override
    protected void onPreExecute(){
        pd = ProgressDialog.show(
                IscrizioniActivity.this,
                "Please wait...",
                "Loading the data",
                true,
                true,
                new DialogInterface.OnCancelListener(){
                    public void onCancel(DialogInterface dialog) {
                        MyTask.this.cancel(true);
                    }
                }
        );
    }

    @Override
    protected Void doInBackground(Void... voids) {
        //do something
        return (null);
    }

    @Override
    protected void onPostExecute(Void voids) {
        pd.dismiss();
        //do something

    }

    public void onDismiss(DialogInterface dialog) {

        this.cancel(true);
    }

}

Regards.

回答1:

pd.setCancelable(true);
    pd.setOnCancelListener(cancelListener);
    bCancelled=false;

 pd is your progressdialog box

and now use cancelListner

    OnCancelListener cancelListener=new OnCancelListener(){
    @Override
    public void onCancel(DialogInterface arg0){
        bCancelled=true;
        finish();
    }
};

回答2:

In your activity, override Back Button, stop the AsyncTask in it, and call finish for current activity.

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
         MyTask.cancel();
      IscrizioniActivity.this.finish();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

回答3:

Have you tried adding a finish() call in the onDismiss() method:

public void onDismiss(DialogInterface dialog) {
    this.cancel(true);
    IscrizioniActivity.this.finish();
}

回答4:

Try this one...

progress_dialog.setCancelable(true);
progress_dialog.setOnCancelListener(new OnCancelListener() {

    @Override
    public void onCancel(DialogInterface dialog) {
        // TODO Auto-generated method stub
        YourActivity.this.finish();
        }
    });

来源：https://stackoverflow.com/questions/8209035/android-stop-asynctask-when-back-button-is-pressed-and-return-to-previous-acti