执行其余代码后，Asyc任务完成了吗？

Question

I am sending HTTP request to server using AsnncTask.I am calling one function checkServer() with three arguments. From this function i am calling a class URLDataProvider().execute("url").get().

When i call checkServer then asynctask is called but after getting response code of 404 checkProtocol method is called. after that OnPostExecute method is called.

After that i again calling checkServer() from Post execute if response code is 404. But the rest of code is called and after that i get the response code of 200 Ok. May i know why checkProtocol() & rest of the code is called before the end of checkServer() .

Here is the code

checkServer("http","servername","firstlogin");

checkProtocol(host_ip, portnumber);
-----------Some code-------------
 new Thread(new Runnable(){

URL DATA PROVIDER

private class UrlDataProvider3 extends AsyncTask<String, Void, String>
{

    String ret="";
    int checkStatus;
    Boolean exception=false;

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

        HttpURLConnection con = null;

        try 
          { 

            HttpURLConnection.setFollowRedirects(true);
            con = (HttpURLConnection) new URL(url[0]).openConnection();
                con.setRequestMethod("HEAD");
                con.setConnectTimeout(20000);



            if(con.getResponseCode()==HttpURLConnection.HTTP_NOT_FOUND && con.getURL().toString().contains("pdata/Login"))
            {

                checkStatus=1;
                return "done";

            }
            else if(con.getResponseCode()==HttpURLConnection.HTTP_NOT_FOUND && con.getURL().toString().contains("cdata/Login"))
            {

                 checkStatus=2;
                 return "done";
            }

            if(con.getResponseCode()==HttpURLConnection.HTTP_OK && con.getURL().toString().contains("pdata/Login"))

            {


                return "done";


            }
            else if(con.getResponseCode()==HttpURLConnection.HTTP_OK && con.getURL().toString().contains("cdata/Login"))
            {



                return "done";

            }

          }

        catch (SocketTimeoutException ste)
        {

            con.disconnect();
            return null;
        }
        catch (IOException e)
          {





          }

    return ret;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);



         if(checkStatus==1)
            {
                if(SettingsChaned)
                {

                 checkServer("http", "cdata","thirdlogin");
                }
                else 
                {

                checkServer("http", "cdata","firstlogin");
                }

            }
            else if(checkStatus==2)
            {
                if(SettingsChaned)
                {

                checkServer("http", "pdata","thirdlogin");
                }
                else
                {

                checkServer("http", "pdata","firstlogin");
                }
            }

}

Answer 1

AsynTask will move your execution to another thread and your so called rest of code is written in UI thread and it will be called before AsynTask is completed.

If you want to execute rest of code after AsynTask do its job you should write that rest of code in onPostExecute

private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
     protected Long doInBackground(URL... urls) {
        // background task
     }



     protected void onPostExecute(Long result) {
        // rest of code
     }
 } 

Change the parameters of AsyncTask accordindly

Answer 2

"AsyncTask enables proper and easy use of the UI thread. This class allows to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.

AsyncTask is designed to be a helper class around Thread and Handler and does not constitute a generic threading framework. AsyncTasks should ideally be used for short operations (a few seconds at the most.) If you need to keep threads running for long periods of time, it is highly recommended you use the various APIs provided by the java.util.concurrent package such as Executor, ThreadPoolExecutor and FutureTask."

With this in mind remeber if you have lines of code outside of the AsynTask for example

{
    new LongOperation().execute(""); //This runs in another thread on its doInBackground() method
    showAToast(); //this is still in the main thread.
    //And so on...
}

the showToastMethod will run on the Main thread while the LongOperation() AsyncTask wil continue in another thread.

For a more in dept with lots of examples you can go to: The Documentation here

Hope it clears your doubt.