How to add a countdown code to a Java app?

I've recently got a project in school.

• Create a Java GUI with an image as background and some textbox.

• the first textbox is just a text that says: Lunch break at 1pm.

• the second textbox is a countdown timer. This timer should appear 5 minutes before the end of the upcoming break, which counts down from 5:00 to 0:00 minutes every second. When reaching 0:00, the timer should respond to a text (e.g. "The
  Presentation will start shortly ").

• Image as a background: done

• Text that says: Lunch break at 1pm: done

• Countdown: I'm stuck at this point. I program a countdown timer first on the console. But I really don't know how to include this countdown to a Java GUI.

Do you have any suggestions?

This is my code for the background:

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Toolkit;
import javax.swing.JPanel;

import javax.swing.*;

public class Bildhintergrund extends JFrame{


	
	//Background
		public Bildhintergrund () {
        setTitle(" Bildhintergrund");
        setSize(Toolkit.getDefaultToolkit().getScreenSize());
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        setLayout(new BorderLayout());
        setContentPane(new JLabel(new ImageIcon("/path/to/bild.jpg")));
		setLayout(new FlowLayout());
		JLabel background = new JLabel();
				add(background);
		
		//Text
	
		JLabel text = new JLabel() {
		      public void paintComponent(Graphics g) {
		        super.paintComponent(g);
		        
		      }
		    };
		;
		    JPanel panel = new JPanel();
		    Dimension size = text.getPreferredSize();
		    getContentPane().add( text );
		    text.setFont(text.getFont().deriveFont((float) 58));
		    text.setText("Lunch break at 1pm");
		    /*text.setAlignmentX(0);
		    text.setAlignmentY(0);*/
		    text.setBounds(300, 300, size.width, size.height);
		    panel.add(text);
		    panel.setLayout(null);
		    add(text);
		}
		public static void main(String[] args) {
	new Bildhintergrund();
}
		}

This is my code for the countdown:

  {
    /*int Time = 5;
    String time;
    int seconds;
    int minutes;*/
    
    int timet= Time * 60; // Convert to seconds
    long delay = timet * 1000;

    do
    {
      minutes = timet / 60;
      seconds = timet % 60;
      time = minutes + ":"  + seconds;
  
	
      System.out.println(GetTimer());
   
      Thread.sleep(1000);
      timet = timet - 1;
      delay = delay - 1000;

    }
    while (delay != 0);
    System.out.println("Another topic will follow");
  
  }
  public static  String GetTimer()
  {
	
	  
  	return  time;
  }
}

You can use javax.swing.Timer like this example:

javax.swing.Timer timer = new javax.swing.Timer(1000/*timer delay between calling ActionListener.actionPerformed(ActionEvent e) (in milliseconds)*/, new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent e) {
				System.out.println("Second over!!!");
				//put your code here
			}
		});
		timer.setRepeats(true);//makes timer repeats forever (or until call timer.stop() method)
		timer.start();