android - 取消异步任务中的进度对话框

Question

我的页面中有搜索框，我也添加了 onTextChangeListener()。当我从搜索框中添加/删除字母/字符时，每次我调用相同的 asyntask。假设调用 3 次，然后创建 3 次进度对话框实例并需要关闭。这里进度对话框没有被关闭。

search.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                searchresult = search.getText().toString();

                if (count == 0) {
                    pageCount = 1;
                    productsList.clear();
                    mCount = 0;
                    if (isTextWatcherVisible) {
//                        GetProductsTask();
                        new GetProductsTask().execute();
                    }
                }
            }
            @Override
            public void afterTextChanged(Editable s) {
            }
        });   
class GetProductsTask extends AsyncTask<Void, Void, Void> {

    final String pcid = Preferences.getString(Preferences.PrefType.enum_company_id, getActivity());

    String url1 = getContext().getString(R.string.url) + "products?company_id=" + pcid + "&page=" + pageCount;

    public GetProductsTask() {
        progressDialog = new ProgressDialog(getActivity());
        progressDialog.setMessage("Loading...");
        progressDialog.setIndeterminate(false);
        progressDialog.setCancelable(false);
    }
    protected void onPreExecute() {
        super.onPreExecute();
//                progressDialog = new ProgressDialog(getActivity());
//                progressDialog.setMessage("Loading...");
//                progressDialog.setIndeterminate(false);
//                progressDialog.setCancelable(false);
        progressDialog.show();

    }

    @Override
    protected Void doInBackground(Void... params) {
      // somthig here
    }
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        ProductslistAdapter adapter = new ProductslistAdapter(getActivity(), R.layout.vendor_products_item, productsList, searchresult);

        list.setAdapter(adapter);
        int count = pageCount - 1;
        list.setSelection(count * 24);
        if (progressDialog.isShowing())
            progressDialog.dismiss();

    }

Answer 1

// here your everytime your creating the dialog box, loosing previous reference. And "progressDialog " is not local to class "GetProductsTask".     
   progressDialog = new ProgressDialog(getActivity());
    progressDialog.setMessage("Loading...");
    progressDialog.setIndeterminate(false);
    progressDialog.setCancelable(false);

解决方案:

class GetProductsTask extends AsyncTask<Void, Void, Void> {
//make it local to class
ProgressDialog progressDialog;