DouKaku?

import java.awt.*;
import java.util.Random;
import java.util.concurrent.*;
import javax.swing.*;

public class Life extends JFrame {
    private boolean[] cells;
    private final int pitch, w, h;

    public static void main(String[] args) {
        Life f = new Life(20, 20, 0.3);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public Life(final int w, final int h, final double rate) {
        super("Life");
        
        this.w = w;
        this.h = h;
        
        pitch = 5;
        cells = new boolean[h*w];
        
        initialize(rate);
        
        getContentPane().add(new JLabel(new Icon() {
            public int getIconHeight() { return h * pitch + pitch; }
            public int getIconWidth() { return w * pitch + pitch; }
            public void paintIcon(Component c, Graphics g, int x, int y) {
                g.setColor(Color.BLUE);
                for (int i = 0; i < h; i++) 
                    for (int j = 0; j < w; j++) 
                        if(cells[at(i, j)]) g.fillRect(j*pitch, i*pitch, pitch, pitch);
            }
        }));
        
        Executors.newScheduledThreadPool(1).scheduleAtFixedRate(new Runnable() {
            public void run() {
                update();
                repaint();
            }
        }, 1000L, 200L, TimeUnit.MILLISECONDS);
    }
    
    private void initialize(double rate) {
        final Random random = new Random(System.currentTimeMillis());
        for (int i = 0; i < h; i++) 
            for (int j = 0; j < w; j++) 
                cells[at(i, j)] = random.nextDouble() < rate;
                                              
    }
    private int at(int i, int j) {
        return i*w + j;
    }
    
    protected void update() {
        boolean[] newG = cells.clone();
        for (int i = 0; i < h; i++) 
            for (int j = 0; j < w; j++) 
                newG[at(i,j)] = next(i, j);
        cells = newG;
    }

    private boolean next(int i, int j) {
        final int u = (i+h-1)%h, d = (i+1)%h, l = (j+w-1)%w, r = (j+1)%w;
        int count = 0;
        if(cells[at(u, j)]) count++;
        if(cells[at(u, r)]) count++;
        if(cells[at(i, r)]) count++;
        if(cells[at(d, r)]) count++;
        if(cells[at(d, j)]) count++;
        if(cells[at(d, l)]) count++;
        if(cells[at(i, l)]) count++;
        if(cells[at(u, l)]) count++;
        
        return ((cells[at(i, j)] && (count == 2 || count == 3))  ||
                (!cells[at(i, j)] && count == 3));
    }
}