Simple Swing

Main.java

import java.awt.event.ActionEvent;
import javax.swing.*;

public class Main {
	public static void main(String[] args) {
		JFrame frame = new JFrame("Simple Swing");
		frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

		JPanel panel = new JPanel();
		frame.getContentPane().add(panel);

		JLabel label = new JLabel("Hello Swing World");
		panel.add(label);

		JButton button = new JButton(new AbstractAction("click me") {
			@Override
			public void actionPerformed(ActionEvent e) {
				JOptionPane.showMessageDialog(null, "This is a message :)", "message", JOptionPane.INFORMATION_MESSAGE);
			}
		});
		panel.add(button);

		frame.pack();
		frame.setVisible(true);
	}
}