在完成之前取消列表視圖適配器的asynctask

Question

我需要取消填充列表視圖適配器之前按下後退按鈕完成列表視圖適配器。通過此代碼

@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(); 
       } 

這是適配器類，我們無法通過在其過程中按回按鈕來取消它。在按下後退按鈕時，活動關閉，但後臺任務繼續。

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

      } 

我試過這個已經沒用了.. !!

Answer 1

請創建一個列表，保存當前的AsyncTask，然後取消它，只要你願意

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

爲您的代碼說明：

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(); 
       }