[hardwired]

Swing works with the event dispatch thread (EDT). It is an attempt to make sure all events occur in proper sequence by having a single queue for all requests to wait in. So doing a time-consuming task like reading data over a network makes everything else wait until the long-running task completes. This has the net affect of freezing the gui and dis-allowing any gui updates to take place while the edt is busy with the long-running task. The solution is to do these long-running tasks on a background thread.
For example:

public void actionPerformed(ActionEvent pt)
{
    if(pt.getSource() == init_Button)
    {
        overallLayout.show(cardPanel, "2"); // please wait JPanel
        loadData();
    }
}

private void loadData()
{
    Thread thread = new Thread(new Runnable()
    {
        public void run()
        {
            try
            {
                // Construct data
                String data = URLEncoder.encode("key1", "UTF-8") + "=" +
                              URLEncoder.encode("value1", "UTF-8");
                data += "&" + URLEncoder.encode("key2", "UTF-8") + "=" +
                              URLEncoder.encode("value2", "UTF-8");

                // Send data
                URL url = new URL("http://www.loaded-designs.com/" +
                                  "posttest/posttest.php");
                URLConnection conn = url.openConnection();
                conn.setDoOutput(true);
                OutputStreamWriter wr =
                    new OutputStreamWriter(conn.getOutputStream());
                wr.write(data);
                wr.flush();
    
                // Get the response
                BufferedReader rd = new BufferedReader(
                            new InputStreamReader(conn.getInputStream()));
                String line;
                while ((line = rd.readLine()) != null) 
                {
                    getback_Label.setText("The PHP variables are below:");
                    getback_Label2.setText(line);
                    System.out.println(line);
                    overallLayout.show(cardPanel, "3");
                }
                wr.close();
                rd.close();
            }
            catch (Exception ex)
            {
                ex.printStackTrace();
            }
        }
    });
    // Keep gui responsive to user input.
    thread.setPriority(Thread.NORM_PRIORITY);  // 5, EDT = 6
    thread.start();
}