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

public class LeftRightButton extends JPanel implements ActionListener {
	private int x = 20;
	private JButton lBtn, rBtn;

	public LeftRightButton() {
		setPreferredSize(new Dimension(200, 70));
		lBtn = new JButton("Left");
		rBtn = new JButton("Right");
		lBtn.addActionListener(this);
		rBtn.addActionListener(this);
		setLayout(new FlowLayout());
		add(lBtn); add(rBtn);
	}

	@Override
	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		g.drawString("HELLO WORLD!", x, 55);
	}

	public void actionPerformed(ActionEvent e) {
		Object source = e.getSource();
		if (source == lBtn) {      // lBtnが押された
			x -= 10;
		}
		else if (source == rBtn) { // rBtnが押された
			x += 10;
		}
		repaint();
	}

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

}