ProgressDialog 在 Toast 出现之前从 AsyncTask 的 doInBackground 方法中消失

Question

我正在使用 AsyncTask 发出 JSON HTTP 请求。我在 onPreExecute() 中创建了一个 ProgressDialog，我在 onPostExecute() 中将其关闭。问题是，diInBackground() 中有一条 Toast 消息显示 JSON response 和 ProgressDialog 在 Toast 出现之前被关闭，意思是 onPostExecute() 在生成 Toast 之前被调用。我怎样才能在 Toast 出现之前关闭它？

这是我的代码。

private  class login extends AsyncTask<Void,Void,Void>{
      private ProgressDialog progressDialog;

      @Override
      protected void onPreExecute(){
          super.onPreExecute();
          // Create & Start Progress Dialog
          progressDialog = new ProgressDialog(LoginActivity.this);
          progressDialog.setMessage("Loading...");
          progressDialog.show();
      }
      @Override
      protected Void doInBackground(Void... params) {
          String url = "http://api.openweathermap.org/data/2.5/weather?q=London,uk";
          JsonObjectRequest req = new JsonObjectRequest(url, null,
                  new Response.Listener<JSONObject>() {

                      @Override
                      public void onResponse(JSONObject response) {

                          try {

                                  Toast.makeText(getApplicationContext(),response.toString() , Toast.LENGTH_SHORT).show();

                              }

                          }
                          catch (Exception e){
                              Toast.makeText(getApplicationContext(),"Server error!..",Toast.LENGTH_SHORT).show();

                          }


                      }
                  }, new Response.ErrorListener() {
              @Override
              public void onErrorResponse(VolleyError error) {
                  VolleyLog.e("from on error response Server Error..: ", error.getMessage());

              }
          });

          AppController.getInstance().addToRequestQueue(req);

            return null;
      }
      @Override
      protected void onPostExecute(Void v){
          // Terminate Progress Dialog
          progressDialog.dismiss();
      }
      }

Answer 1

try {

                              Toast.makeText(getApplicationContext(),response.toString() , Toast.LENGTH_SHORT).show();

                          }

                      }
                      catch (Exception e){
                          Toast.makeText(getApplicationContext(),"Server error!..",Toast.LENGTH_SHORT).show();

                      }

这段代码完全错误。 您不能从 doInBackground. 添加 Toast。你需要在关闭 dioalog 后移动它

// Terminate Progress Dialog
      progressDialog.dismiss();
//Add your Toast here

Answer 2

您可以在 toast 显示后使用 TimerTask 手动关闭对话框。您可以查看如何使用 TimerTask HERE。您正在使用 Toast.LENGTH_SHORT，因此吐司将显示 2 秒。

Answer 3

无需在Async Task中编写Volley Request。您可以直接执行该任务，因为它在内部使用线程。因此，一旦您收到响应或失败，您就可以自行关闭对话框。我想它会对你有所帮助

 String url = "http://api.openweathermap.org/data/2.5/weather?q=London,uk";
      JsonObjectRequest req = new JsonObjectRequest(url, null,
              new Response.Listener<JSONObject>() {

                  @Override
                  public void onResponse(JSONObject response) {

      if(progressDialog.isShowing){
     progressDialog.cancel();
       }
                      try {

                              Toast.makeText(getApplicationContext(),response.toString() , Toast.LENGTH_SHORT).show();

                          }

                      }
                      catch (Exception e){
                          Toast.makeText(getApplicationContext(),"Server error!..",Toast.LENGTH_SHORT).show();

                      }


                  }
              }, new Response.ErrorListener() {
          @Override
          public void onErrorResponse(VolleyError error) {
              VolleyLog.e("from on error response Server Error..: ", error.getMessage());
  if(progressDialog.isShowing){
 progressDialog.cancel();
   }
          }
      });

      AppController.getInstance().addToRequestQueue(req);

希望这对您有所帮助而且不需要 AsyncTask。

Answer 4

关闭响应和错误侦听器中的进度对话框...无需关闭 post 方法

private  class login extends AsyncTask<Void,Void,Void>{
  private ProgressDialog progressDialog;

  @Override
  protected void onPreExecute(){
      super.onPreExecute();
      // Create & Start Progress Dialog
      progressDialog = new ProgressDialog(LoginActivity.this);
      progressDialog.setMessage("Loading...");
      progressDialog.show();
  }
  @Override
  protected Void doInBackground(Void... params) {
      String url = "http://api.openweathermap.org/data/2.5/weather?q=London,uk";
      JsonObjectRequest req = new JsonObjectRequest(url, null,
              new Response.Listener<JSONObject>() {

                  @Override
                  public void onResponse(JSONObject response) {

                      try {

                              Toast.makeText(getApplicationContext(),response.toString() , Toast.LENGTH_SHORT).show();

                          }

                      }
                      catch (Exception e){
                          Toast.makeText(getApplicationContext(),"Server error!..",Toast.LENGTH_SHORT).show();
      progressDialog.dismiss(); add this line

                      }


                  }
              }, new Response.ErrorListener() {
          @Override
          public void onErrorResponse(VolleyError error) {
              VolleyLog.e("from on error response Server Error..: ", error.getMessage());
      progressDialog.dismiss(); add this line

          }
      });

      AppController.getInstance().addToRequestQueue(req);

        return null;
  }
  @Override
  protected void onPostExecute(Void v){
      // Terminate Progress Dialog
      //progressDialog.dismiss(); comment this line
  }
  }

Answer 5

你想要打印吐司消息然后你可以使用处理程序.

   Handler h = new Handler(this.getMainLooper());
                h.post(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),response.toString() , Toast.LENGTH_SHORT).show();
                        //stopProgress 
                    }
                });

ProgressDialog 在 Toast 出现之前从 AsyncTask 的 doInBackground 方法中消失

ProgressDialog getting Dismissed before Toast appears from doInBackground method of AsyncTask

android

json

progressdialog

android-asynctask