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

public class Graph2 extends JPanel
                    implements ActionListener {
    private int[] is = {};
    private JTextField input;
    private final Color[] cs = {
        Color.RED, Color.BLUE
    };
    private final int scale = 15;
    
    public Graph2() {
        setPreferredSize(new Dimension(200, 200));
        input = new JTextField("", 16);
        input.addActionListener(this);
        setLayout(new FlowLayout());
        add(input);
    } 

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        int i;
        int n = is.length;

        for (i = 0; i < n; i++) {
            g.setColor(cs[i % 2]);
            g.fillRect(0, i * scale + 30,
                       is[i] * scale, scale);
        }
    }

    public void actionPerformed(ActionEvent e) {
        String[] args = input.getText().split(" ");
        int n = args.length;
        is = new int[n];

        int i;
        for (i = 0; i < n; i++) {
            is[i] = Integer.parseInt(args[i]);
        }
        repaint();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame("グラフ");
            frame.add(new Graph2());
            frame.pack();
            frame.setVisible(true);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        });
    }
}