Question

我需要在按下后退按钮之前取消填充列表视图适配器的asynctask。通过此代码

@Override
public View getView(final int position, View convertView, ViewGroup parent) {

    if(convertView==null){
        LayoutInflater inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);convertView=inflater.inflate(R.layout.seatadapter, null);

         TextView text3=(TextView)convertView.findViewById(R.id.text3);
         ProgressBar progressBar1=(ProgressBar)convertView.findViewById(R.id.progressBar1);
         TextView predic=(TextView)convertView.findViewById(R.id.textView3);
         TextView classs=(TextView)convertView.findViewById(R.id.textView4);
         ImageView img1=(ImageView)convertView.findViewById(R.id.imageView1);

new update(classs,predic, text3, progressBar1,img1).execute(tarinname.get(position), Date.get(position), Ffrom.get(position), Tto.get(position), Ccl.get(position));

class update extends AsyncTask{

@Override
        protected Object doInBackground(Object... params) {

Code For Json Parsing....
}
        protected void onPostExecute(Object result) {
            super.onPostExecute(result);

            if (this.result.contains("CurrentStatus")) {
                 progressBar.setVisibility(progressBar.GONE);

                 t.setVisibility(t.VISIBLE);
                 t3.setVisibility(t3.VISIBLE);
                im1.setVisibility(im1.VISIBLE);

                 t3.setText("Class "+TravelClass);

                 t1.setText(perdcition);

                 if (ConfirmTktStatus.contains("Confirm")) {
                    im1.setImageResource(R.drawable.img_green);

                }
                 if (ConfirmTktStatus.contains("Probable")) {

                    }
                 if (ConfirmTktStatus.contains("No Chance")) {

                    }

                t.setText(var1);

            }else {
                 progressBar.setVisibility(progressBar.GONE);
            }


                Toast.makeText(context, var, Toast.LENGTH_LONG).show();
                }

这是适配器类，我们无法在其过程中按后退按钮取消它。按下后退按钮后，活动将关闭，但后台任务将继续。

@Override
            protected void onCancelled() {
                // TODO Auto-generated method stub
                super.onCancelled();
                ((Activity)context).finish();

            }

我已经尝试过但没有用.. !!

Answer 1

请创建一个列表来存储当前的AsyncTask，然后随时取消

for (AsyncTask myAsyncTask : myAsyncTasks) {
    if (myAsyncTask.getStatus().equals(AsyncTask.Status.RUNNING)) {
        myAsyncTask.cancel(true);
    }
}
myAsyncTasks.clear();

代码详情：

private List<AsyncTask> myAsyncTasks = new ArrayList<>();
public void addRunningTask(AsyncTask task) {
    myAsyncTasks.add(task);
}

public void cancelRunningTasks() {
    for (AsyncTask myAsyncTask : myAsyncTasks) {
        if (myAsyncTask.getStatus().equals(AsyncTask.Status.RUNNING)) {
            myAsyncTask.cancel(true);
        }
    }
    myAsyncTasks.clear();
}
@Override
public void onBackPressed() {
    cancelRunningTasks();
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {

    if(convertView==null){
        LayoutInflater inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);convertView=inflater.inflate(R.layout.seatadapter, null);

         TextView text3=(TextView)convertView.findViewById(R.id.text3);
         ProgressBar progressBar1=(ProgressBar)convertView.findViewById(R.id.progressBar1);
         TextView predic=(TextView)convertView.findViewById(R.id.textView3);
         TextView classs=(TextView)convertView.findViewById(R.id.textView4);
         ImageView img1=(ImageView)convertView.findViewById(R.id.imageView1);

AsyncTask task = new update(classs,predic, text3, progressBar1,img1);
task.execute(tarinname.get(position), Date.get(position), Ffrom.get(position), Tto.get(position), Ccl.get(position));
addRunningTask(task);

class update extends AsyncTask{

@Override
        protected Object doInBackground(Object... params) {

Code For Json Parsing....
}
        protected void onPostExecute(Object result) {
            super.onPostExecute(result);

            if (this.result.contains("CurrentStatus")) {
                 progressBar.setVisibility(progressBar.GONE);

                 t.setVisibility(t.VISIBLE);
                 t3.setVisibility(t3.VISIBLE);
                im1.setVisibility(im1.VISIBLE);

                 t3.setText("Class "+TravelClass);

                 t1.setText(perdcition);

                 if (ConfirmTktStatus.contains("Confirm")) {
                    im1.setImageResource(R.drawable.img_green);

                }
                 if (ConfirmTktStatus.contains("Probable")) {

                    }
                 if (ConfirmTktStatus.contains("No Chance")) {

                    }

                t.setText(var1);

            }else {
                 progressBar.setVisibility(progressBar.GONE);
            }


                Toast.makeText(context, var, Toast.LENGTH_LONG).show();
                }

在列表视图适配器完成之前取消它的asynctask

1 个答案: