package main;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.WindowConstants;
import javax.swing.event.MenuEvent;

import java.awt.Dimension;

@SuppressWarnings("serial")
public class ApplicationFrame extends JFrame
{
	protected static ApplicationFrame instance;

	private ApplicationFrame()
	{
		setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
		buildGui();
		setSize(new Dimension(getToolkit().getScreenSize()));
		setVisible(true);
	}

	private void buildGui()
	{
		final JMenu menu = new JMenu("Menu");
		menu.addMenuListener(
			new MenuAdapter()
			{
				@Override
				public void menuSelected(@SuppressWarnings("unused") final MenuEvent event)
				{
					menu.removeAll();
					for (int i = 0; i < 3; ++i)
					{
						menu.add(new JMenuItem("Item " + i));
					}
				}
			}
		);
		final JMenuBar menuBar = new JMenuBar();
		menuBar.add(menu);
		setJMenuBar(menuBar);
	}

	public static ApplicationFrame getInstance()
	{
		if (instance == null)
		{
			instance = new ApplicationFrame();
		}
		return instance;
	}
}