等待AsyncTask(Waiting for AsyncTask)

 在我的应用程序中，我需要从2个不同的URL下载一些数据，然后填充列表。 为此，我创建了一个2个AsyncTask类。 第一类负责从相应的URL下载数据。 另一个负责执行上述的asyncTasks，然后在UI线程上填充列表。 我需要下载数据并行运行的任务，所以我在执行程序上执行它们。 我的问题是负责填充列表的任务在其他两个任务下载数据之前终止。 如何让该线程等待其他两个返回。 我应该在其他人身上使用.get，因为我需要它们并行运行。 我也发布了一些代码以便清楚。 
 
    protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

                          readJsonTask task = new readJsonTask(this);


          task.execute();
    }

      private class readJsonTask extends AsyncTask<String, Void, String> {

            @Override
            protected String doInBackground(String... args) {

              downloadUrl task = new downloadUrl(url1,"jsonData1","/sdcard/appData/LocalJson/jsonData1");
              task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

              downloadUrl task1 = new downloadUrl(url2,"jsonData2","/sdcard/appData/LocalJson/jsonData2");
              task1.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

             return "done"; 

      }


        @Override
        protected void onPostExecute(String result) {

            //update UI

        }
    }


      private class downloadUrl extends AsyncTask<String, Void, String> {

        private String url;
        private String targetFolder;
        private String pathForLoad;



            @Override
        protected String doInBackground(String... args) {               


            //download Data


            return "done"; 
        }

        @Override
        protected void onPostExecute(String result) {               



        }
  }

In my application I need to download some data from 2 different urls, and then populate a list. To do so I create one 2 AsyncTask classes. The first class is responsible for downloading the data from the corresponding url. The other one is responsible for executing the aforementioned asyncTasks and after that populating a list on the UI thread. I need the tasks that download data to be run in parallel so I execute them on the executor. My problem is that the task that is responsible for populating the list terminates before the other two tasks download the data. How can I make that thread wait for the other two to return. I should use .get on the others because i need them to run in parallel. I'm also posting some code in order to be clear.
 
    protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

                          readJsonTask task = new readJsonTask(this);


          task.execute();
    }

      private class readJsonTask extends AsyncTask<String, Void, String> {

            @Override
            protected String doInBackground(String... args) {

              downloadUrl task = new downloadUrl(url1,"jsonData1","/sdcard/appData/LocalJson/jsonData1");
              task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

              downloadUrl task1 = new downloadUrl(url2,"jsonData2","/sdcard/appData/LocalJson/jsonData2");
              task1.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

             return "done"; 

      }


        @Override
        protected void onPostExecute(String result) {

            //update UI

        }
    }


      private class downloadUrl extends AsyncTask<String, Void, String> {

        private String url;
        private String targetFolder;
        private String pathForLoad;



            @Override
        protected String doInBackground(String... args) {               


            //download Data


            return "done"; 
        }

        @Override
        protected void onPostExecute(String result) {               



        }
  }

原文：https://stackoverflow.com/questions/19377331