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);
        });
    }
}