java - 关于任务 onPostExecute

Question

我有一个运行良好的 AsyncTask 类，但在这个类中，我在 onPreExecute 中有一个 ProgressDialog，它工作正常，但我需要在完成进程对话框关闭时，我将代码放在 onPostExecute 中，这方式:

protected void onPostExecute() {
    progress.dismiss();
}

但它什么也没做。该对话框不会关闭。这是所有代码:

public class JsonRequest extends AsyncTask<String, Void, ArrayList<String>> {

private final Context context;
private ArrayList<String> stringArray = new ArrayList<String>();
private ProgressDialog progress;

public JsonRequest(Context c){
    this.context = c;
}

protected void onPreExecute(){
    progress= new ProgressDialog(this.context);
    progress.setMessage("Loading");
    progress.show();
}

@Override
protected ArrayList<String> doInBackground(String... params) {
    try {

        final String POST_PARAMS = params[1];

        URL obj = new URL(params[0]);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("POST");
        con.setRequestProperty("User-Agent", "Mozilla/5.0");

        // For POST only - START
        con.setDoOutput(true);
        OutputStream os = con.getOutputStream();
        os.write(POST_PARAMS.getBytes());
        os.flush();
        os.close();
        // For POST only - END

        int responseCode = con.getResponseCode();
        System.out.println("POST Response Code :: " + responseCode);

        if (responseCode == HttpURLConnection.HTTP_OK) { //success
            BufferedReader in = new BufferedReader(new InputStreamReader(
                    con.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();

            JSONArray myListsAll= new JSONArray(response.toString());
            for(int i=0;i<myListsAll.length();i++){

                JSONObject jsonObject = myListsAll.getJSONObject(i);
                this.stringArray.add(jsonObject.toString());
            }

        } else {
            System.out.println("POST request not worked");
        }


    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return this.stringArray;
}

protected void onPostExecute() {
    progress.dismiss();
}

所以我调用:

public class MyActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
    private void createListView() {
        itens = new ArrayList<ItemFeedsListView>();

        String[] itensUrl = {"url","data"};
        JsonRequest task = new JsonRequest(this);
        try {
            ArrayList<String> result = task.execute(itensUrl).get();

            for(int i = 0 ; i < result.size() ; i++) {
                String currentList = result.get(i);
                JSONObject jsonobject = new JSONObject(currentList);

                ItemFeedsListView item = new ItemFeedsListView(jsonobject.optString("value1"),jsonobject.optString("value2"),jsonobject.optString("valeu3"),jsonobject.optString("value4"),jsonobject.optString("value5"), R.mipmap.eu, R.mipmap.logo);
                itens.add(item);

            }

        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }

        //Cria o adapter
        adapterListView = new AdapterFeedsListView(this, itens);

        //Define o Adapter
        listView.setAdapter(adapterListView);
        //Cor quando a lista é selecionada para ralagem.
        listView.setCacheColorHint(Color.TRANSPARENT);
    }
}

Answer 1

你没有调用正确的 onPostExecute:

你需要:

@Override
 protected void onPostExecute(ArrayList<String> data) {
    super.onPostExecute(data);
    progress.dismiss();
}

问题是您没有通过添加 onPostExecute() 来覆盖 AsyncTask 类中的方法。您需要添加 @Override 注释并传入 AsyncTask 类的返回类型。