The Game of Life

Life.java

package life;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.Timer;


public class Life extends JFrame {
    
    public static int W = 800;
    public static int H = 500;
    
    public static int cellW = 5;
    public static int cellH = 5;
    
    public static int n = W/cellW;
    public static int m = H/cellH;
    
    public static double fillRate = 0.92;
    public static boolean stopGraphics = false;
    Timer timer = new Timer(100, new TimerListener());
    public static int[][] cells = new int[n][m];
    public static int[][] copy = new int[n][m];
    public static boolean initialize = true;
    public static JSlider threshold;
    public static boolean mutate = false;
    public static JButton mutation = new JButton("Mutate: off");
    public static boolean grid = true;
    
    public Life(){
        timer.start();
        DrawingPanel p = new DrawingPanel();
        
        JButton stop = new JButton("Start/Stop");
        stop.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                stopGraphics = !stopGraphics;
            }
        });
        
        JButton init = new JButton("init");
        init.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                initialize = true;
                stopGraphics = true;
            }
        });
        
        threshold = new JSlider(JSlider.HORIZONTAL, 0, 100, 50);
        p.add(init);
        p.add(stop);
        p.add(threshold);
        this.add(p);
    }
    
    static class DrawingPanel extends JPanel{
        public DrawingPanel(){
            initializeCells();
        }
        
        public void initializeCells(){
            for(int x = 0; x < n; x++){
                for(int y = 0; y < m; y++){
                   cells[x][y] = Math.random() > fillRate ? 1 : 0;
                }
            }
        }
    
        protected void paintComponent(Graphics g){
            super.paintComponents(g);
            if(initialize){
                fillRate = threshold.getValue()/100.0;
                initializeCells();
            }

            initialize = false;
            if(grid){
                drawGrid(g);
            }

            if(!stopGraphics){
                createCopy();
                updateGrid();
            }
        }


        private void updateGrid(){
            for(int x = 0; x < n; x++){
                for(int y = 0; y < m; y++){
                   cells[x][y] = copy[x][y];
                }
            }
        }
    
        private void createCopy(){
            for(int x = 0; x < n; x++){
                for(int y = 0; y < m; y++){
                    copy[x][y] = cells[x][y];
                    int count = getNeighborCount(x, y);
                    if(cells[x][y] == 1 && count < 2){
                        copy[x][y] = 0;
                    }
                    if(cells[x][y] == 1 && (count == 2 || count == 3)){
                        copy[x][y] = 1;
                    }
                    if(cells[x][y] == 1 && count > 3){
                        copy[x][y] = 0;
                    }
                    if(cells[x][y] == 0 && count == 3){
                        copy[x][y] = 1;
                    }
                }
            }
        }
        
        private void drawGrid(Graphics g){
            Random rand = new Random();
            g.drawRect(0, 0, W, H);
            for(int x = 0; x < n; x++){
                for(int y = 0; y < m; y++){
                    int i = x * cellW;
                    int o = y * cellH;
                    if(cells[x][y] == 1){
                        g.setColor(Color.BLACK);
                        g.fillRect(i, o, cellW, cellH);
                        g.drawRect(i, o, cellW, cellH);
                    }
                    
                    if(cells[x][y] == 0){
                        if(Math.random() < 0.0001){
                            cells[x][y] = 1;
                        }
                    }
                }
            }
        }
        
        public static int getNeighborCount(int x, int y){
            int xMinus = (x - 1) % n;
            if(xMinus == -1){
                xMinus = n-1;
            }
            int xPlus = (x + 1) % n;
            
            int yMinus = (x - 1) % m;
            if(yMinus == -1){
                yMinus = m-1;
            }
            int yPlus = (y + 1) % m;
            
            int sum = cells[xMinus][yMinus]
                    + cells[x][yMinus]
                    + cells[xPlus][yMinus]
                    + cells[xMinus][y]
                    + cells[xPlus][y]
                    + cells[xMinus][yPlus]
                    + cells[x][yPlus]
                    + cells[xPlus][yPlus];
            
            return sum;
        }
    }
    
    public class TimerListener implements ActionListener{
        public void actionPerformed(ActionEvent e){
            repaint();
        }
    }
    
    public static void main(String[] args) {
        Life frame = new Life();
        frame.setTitle("The Game of Life");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(W, H);
        frame.setVisible(true);
    }
}