How to make this GUI window

public class PhoneListGUI implements ActionListener{
 
    JFrame guiFrame;
    JPanel buttonPanel;
    JButton button;
    JList list;
    
    public PhoneListGUI() {
	
        guiFrame = new JFrame();
        
        //make sure the program exits when the frame closes
        guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        guiFrame.setTitle("Phone List");
        guiFrame.setSize(300,300);
      
        
        //This will center the JFrame in the middle of the screen
        guiFrame.setLocationRelativeTo(null);

        Container contentPane = guiFrame.getContentPane();      
        contentPane.setLayout(new BorderLayout());
        

        JPanel buttonPanel = new JPanel();
      
        JButton newButton = new JButton("New Number");
        buttonPanel.add(newButton);
        JButton delButton = new JButton("Delete Number");
      	buttonPanel.add(delButton);
      

      	JButton exitButton = new JButton("Exit");
      	buttonPanel.add(exitButton);
   
        list = new JList<>();
          
        contentPane.add(buttonPanel, BorderLayout.WEST);
        contentPane.add(list, BorderLayout.EAST);

        guiFrame.setVisible(true);
    }

	@Override
	public void actionPerformed(ActionEvent e) {
		// TODO Auto-generated method stub
		
	}
}