Progress dialog async task taking longer time than expected

问题

I am new to android programming. I am developing a web crawler for which i am using a Async Task and it is working well.In order to keep user informed,i am using progress dialog. My problem is,if i use a Progress Dialog my program takes more time to execute and when i won`t use the progress dialog,it executes faster.

Done Work OnCreate Method

 protected void onCreate(Bundle savedInstanceState) {
    try {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_results);

        Intent intent = getIntent();

        s1 = intent.getStringExtra("Number1");
        s2 = intent.getStringExtra("Number2");
        s3=intent.getIntExtra("selectedItem",0);
        HttpAsyncTask asyncTask = new HttpAsyncTask();
        asyncTask.execute();


    }catch (Exception e)
    {
        messageBox("Exception",e.getMessage());
    }

}

Async Task Class

 private class HttpAsyncTask extends AsyncTask<List<String>, Integer, List<String>> {
    private ProgressDialog dialog;
    @Override
    protected void onPreExecute() 
     {
        dialog = new ProgressDialog(Results.this);
        dialog.setIndeterminate(true);
        dialog.setMessage("Please Wait");
        dialog.setCancelable(true);
        dialog.show();
        super.onPreExecute();
    }
    @Override
    protected List<String> doInBackground(List<String>... urls) {
        //android.os.Debug.waitForDebugger();
       // spinner.setVisibility(View.VISIBLE);
        List<String>resultList=new ArrayList<String>();
        try
        {
            if(isCancelled())
                return resultList;

         resultList=WebCrawlerClass.GetPost(s1,s2,s3);

        }catch (Exception e)
            {
                messageBoxs("Error", e.getMessage());
            }
       return resultList;
    }


    // onPostExecute displays the results of the AsyncTask.
    @Override
    protected void onPostExecute(List<String> result)
    {

    if(dialog.isShowing())
    {
     dialog.dismiss();
    }
        if(s3 == 2)
        {
            docListAdapter=new ListViewData(Results.this,result);
        }
        else {
            docListAdapter = new NameNumListData(Results.this, result);
        }

        docList=(ListView)findViewById(R.id.listView2);
        docList.setAdapter(docListAdapter);
        super.onPostExecute(result);
    }

    @Override
    protected void onCancelled() {
        super.onCancelled();
        this.cancel(true);
    }
}

Am I missing something? Need help..

Thanks and Regards, Abhinav

回答1:

In you activity

// Start the progress dialog ..

Handler handler = new Handler() {
      @Override
       public void handleMessage(Message msg) {
       super.handleMessage(msg);
         // dismiss the progress dialog
      }
    };
 HttpAsyncTask asyncTask = new HttpAsyncTask(handler);
 asyncTask.execute();

In your asynctask class

private class HttpAsyncTask extends AsyncTask<List<String>, Integer, List<String>> {

    private Handler handler = null;
    public HttpAsyncTask (Handler handler) {
        this.handler = handler;
    }

    protected Void doInBackground(Void... params) {
       //Perform your task
       // When you know that task is finished , fire following code
                if (null != handler) {
                  Message message = handler.obtainMessage();
                        message.obj = Any data you want to sent to the activity
                        message.what = 1 ; ( Optional )
                        handler.sendMessage(message);
                }

    }

Thus when sendMessage function is called from doInbackground.. your handleMessage in your activity will get triggered and then you should dismiss the progress dialog

Hope this will improve the performance issue what you are facing

回答2:

Remove super.onPreExecute(); in onPreExecute() method and check .It might Help

来源：https://stackoverflow.com/questions/28124150/progress-dialog-async-task-taking-longer-time-than-expected