Something

public void createTopMenu(String menuName) {
    	JFrame frame = new JFrame();
    	frame.setTitle("Create a new menu");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(new Dimension(200,200));
        
        
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension frameSize = frame.getSize();
        frame.setLocation((screenSize.width - frameSize.width) / 2,(screenSize.height - frameSize.height) /2 );

        //Create and set up the content pane.
        TopMenu contentPane = new TopMenu(frame, menuName);
        contentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(contentPane);
        frame.validate();

        //Display the window.
        frame.pack();
        frame.setVisible(true);
       	System.out.println(frame.getSize());	
    }

///////////////////////////////////////////////
class TopMenu extends JPanel {
 	
 	JFrame frame;
 	JPanel foodListPanel;
 	JButton addItemButton;
 	
 	TopMenu(JFrame frame, String menuName) {
 		super(new BorderLayout());
 		this.frame = frame;
 		//frame.setSize(new Dimension(200,200));
 		
 		JPanel topPanel = new JPanel();
 		JLabel menuNameLabel = new JLabel(menuName, JLabel.LEFT);
 		topPanel.add(menuNameLabel);
 		
 		ActionListener buttonListener = new ActionListener() {
 			
 			public void actionPerformed(ActionEvent e) {
 				if (e.getSource() == addItemButton) {
 					String s = JOptionPane.showInputDialog(null, "Enter Menu Item:", "Menu Item", JOptionPane.QUESTION_MESSAGE);
 					foodListPanel.add(new JLabel(s));
 					updateUI();
 				}
 			}
 		};
 			
 		
 		
 		JPanel bottomPanel = new JPanel();
 		addItemButton = new JButton("Add Item");
 		addItemButton.addActionListener(buttonListener);
 		JButton doneButton = new JButton("Done");
 		bottomPanel.add(addItemButton);
 		bottomPanel.add(doneButton);
 		
 		frame.validate();
 		
 		foodListPanel = new JPanel();
 		foodListPanel.setLayout(new GridLayout(7, 0));
 		//JScrollPane scrollPane = new JScrollPane();
 		//scrollPane.add(foodListPanel);
 		
 		add(topPanel, BorderLayout.NORTH);
 		add(foodListPanel, BorderLayout.CENTER);
 		add(bottomPanel, BorderLayout.SOUTH);
 	}
 }