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

public class ChangeColor extends JPanel implements ActionListener {
	private final Color[] cs = {Color.RED, Color.BLUE, Color.GREEN, Color.ORANGE};
	private int i = 0;
	private JLabel label;
	
	public ChangeColor() {
		JButton b = new JButton("Next");
		b.addActionListener(this);
		label = new JLabel("HELLO WORLD!");
		label.setForeground(cs[i]);
		setLayout(new FlowLayout());
		add(b); add(label);
	}
	
	public void actionPerformed(ActionEvent e) {
		i = (i + 1) % cs.length;
		label.setForeground(cs[i]);
	}

	public static void main(String[] args) {
		SwingUtilities.invokeLater(() -> {
			JFrame frame = new JFrame("Change Color");
			frame.add(new ChangeColor());
			frame.pack();
			frame.setVisible(true);
			frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		});
	}
}