Progress bar is not displaying immediately

I'am sending a complaint to server after clicking on submit button from my activity class. And Here is my code to display a progress bar while the complaint is sending to server. But it is not displaying immediately after clicking on submit. It is displaying the progress bar just before getting the response from server.

case R.id.submit: 
    ProgressDialog.show(this, " " , " S开发者_如何学JAVAending Complaint. \n Please wait ... ", true);
    /*...code to send complaint and get the response....*/

Please help me

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do your server communication in the separate thread not in the UI thread which you are doing currently..