DouKaku?

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.AbstractAction;
import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class RandomWalk extends JFrame {
    private static final int WIDTH = 640;
    private static final int HEIGHT = 480;
    private static final Dimension PLOT_SIZE = new Dimension(WIDTH, HEIGHT);

    private final JTextField countField_ = new JTextField(8);
    private final JButton startButton_ = new JButton(new AbstractAction("開始") {
        public void actionPerformed(ActionEvent e) { start(); }
    });
    private final JButton stopButton_ = new JButton(new AbstractAction("停止") {
        public void actionPerformed(ActionEvent e) { stop(); }
    });
    private final JButton endButton_ = new JButton(new AbstractAction("終了") {
        public void actionPerformed(ActionEvent e) { dispose(); }
    });

    private final Random random_ = new Random();

    private volatile boolean walking_ = false;
    private final List<Point> points_ = new ArrayList<Point>();

    public RandomWalk() {
        super("2次元ランダムウォーク");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setResizable(false);

        configure();

        Box main = Box.createVerticalBox();
        main.add(createOperationArea());
        main.add(createPlotArea());
        this.add(main);

        Timer timer = new Timer();
        timer.schedule(new TimerTask() {
            public void run() {
                repaint();
            };
        }, 0, 100L);
    }
    private void configure() {
        countField_.setText("1000");

        startButton_.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
        stopButton_.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
    }

    private JComponent createPlotArea() {
        plotArea_.setBackground(Color.WHITE);
        plotArea_.setPreferredSize(PLOT_SIZE);
        return plotArea_;
    }
    private JComponent createOperationArea() {
        JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT));
        panel.add(new JLabel("N="));
        panel.add(countField_);
        panel.add(Box.createHorizontalGlue());
        panel.add(startButton_);
        panel.add(stopButton_);
        panel.add(endButton_);
        return panel;
    }


    public void start() {
        initialize();
        walking_ = true;
    }
    public void stop() {
        walking_ = false;
    }


    private void initialize() {
        int count = 1;
        try {
            count = Integer.parseInt(countField_.getText());
        } catch (NumberFormatException e) {
        }
        points_.clear();
        points_.add(new Point(WIDTH / 2, HEIGHT / 2));
        for (int index = 1; index < count; index++) {
            points_.add(new Point(random_.nextInt(WIDTH), random_.nextInt(HEIGHT)));
        }
    }

    private final JPanel plotArea_ = new JPanel() {
        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);

            if (walking_) {
                for (Point p: points_) {
                    nextStep(p);
                    g.drawRect(p.x, p.y, 1, 1);
                }
            }
        }
        private void nextStep(Point p) {
            switch (random_.nextInt(4)) {
                case 0:
                    p.x--;
                    break;
                case 1:
                    p.x++;
                    break;
                case 2:
                    p.y--;
                    break;
                case 3:
                    p.y++;
                    break;
            }
        }
    };


    public static void main(String[] args) {
        RandomWalk frame = new RandomWalk();
        frame.pack();
        frame.setVisible(true);
    }
}