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

public class LeftRightButton4 extends JPanel {
    private int x = 20;

    public LeftRightButton4() {
        setPreferredSize(new Dimension(200, 70));
        JButton lBtn = new JButton("Left");
        JButton rBtn = new JButton("Right");
        lBtn.addActionListener(e -> {
            x -= 10;
            repaint();
        });
        rBtn.addActionListener(e -> {
            x += 10;
            repaint();
        });
        setLayout(new FlowLayout());
        add(lBtn); add(rBtn);
    }

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

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame("ボタン");
            frame.add(new LeftRightButton4());
            frame.pack();
            frame.setVisible(true);;
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        });
    }
}