https://qiita.com/pkodama/items/ce5d933085c7b46848bb#comment-abb5ce1fb1c96db54da3

LifeGame.java

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

class Life {
    private static final String DEAD = "0";
    private static final String ALIVE = "1";
    private String state = DEAD;

    public void dead() { state = DEAD; }
    public void alive() { state = ALIVE; }
    public void flip() { state = state == ALIVE ? DEAD : ALIVE; }
    public boolean isDead() { return state == DEAD; }
    public boolean isAlive() { return state == ALIVE; }
    public String toString() { return state; }
}

class Map {
    public final int height, width;
    private final Life[][] lives;
    private static final int[] DX = {1, 1, 0, -1, -1, -1, 0, 1};
    private static final int[] DY = {0, 1, 1, 1, 0, -1, -1, -1};

    public Map(int height, int width) {
        this.height = height;
        this.width = width;
        lives = new Life[height][width];
        for (int y = 0; y < height; y++)
            for (int x = 0; x < width; x++)
                lives[y][x] = new Life();
    }

    public Map clone() {
        Map map = new Map(height, width);
        for (int y = 0; y < height; y++)
            for (int x = 0; x < width; x++)
                if (isAlive(y, x))
                    map.alive(y, x);
        return map;
    }

    public void print() {
        for (var row: lives) {
            for (var life: row)
                System.out.print(life);
            System.out.println();
        }
        System.out.println();
    }

    public void reset() {
        for (var row: lives)
            for (var life: row)
                life.dead();
    }

    public void dead(int y, int x) { lives[y][x].dead(); }

    public void alive(int y, int x) { lives[y][x].alive(); }

    public void flip(int y, int x) { lives[y][x].flip(); }

    public boolean isDead(int y, int x) { return !isAlive(y, x); }

    public boolean isAlive(int y, int x) {
        return 0 <= y && y < height && 0 <= x && x < width &&
               lives[y][x].isAlive();
    }

    public int countNeighborAlives(int y, int x) {
        int alives = 0;
        for (int d = 0; d < DY.length; d++)
            if (isAlive(y + DY[d], x + DX[d]))
                alives++;
        return alives;
    }
}

class MapUI extends JPanel {
    private final Map map;

    private class LifeUI extends JButton {
        private int y, x;
        private static final int SIZE = 10;

        public LifeUI(int y, int x) {
            this.y = y;
            this.x = x;
            setPreferredSize(new Dimension(SIZE, SIZE));
            addActionListener(event -> map.flip(y, x));
        }

        public void paint(Graphics g) {
            setBackground(map.isAlive(y, x) ? Color.RED : Color.BLACK);
            super.paint(g);
        }
    }

    public MapUI(Map map) {
        this.map = map;
        setLayout(new GridLayout(map.height, map.width));
        for (int y = 0; y < map.height; y++)
            for (int x = 0; x < map.width; x++)
                add(new LifeUI(y, x));
    }
}

class LifeGameUI {
    private final LifeGame game;
    private final JFrame frame;
    private final MapUI map;
    private final JLabel generation;

    static {
        try {
            UIManager.setLookAndFeel(
                    UIManager.getCrossPlatformLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public LifeGameUI(LifeGame game) {
        this.game = game;

        frame = new JFrame("LifeGame");
        frame.getContentPane().setBackground(Color.BLACK);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel north = new JPanel();
        north.setPreferredSize(new Dimension(400, 100));
        north.setLayout(null);

        JButton startButton = new JButton("START");
        startButton.setBounds(20, 20, 100, 20);
        startButton.addActionListener(event -> game.start());
        north.add(startButton);

        JButton stopButton = new JButton("STOP");
        stopButton.setBounds(20, 50, 100, 20);
        stopButton.addActionListener(event -> game.stop());
        north.add(stopButton);

        JButton resetButton = new JButton("RESET");
        resetButton.setBounds(150, 20, 100, 20);
        resetButton.addActionListener(event -> game.reset());
        north.add(resetButton);

        generation = new JLabel("Generation : " + game.generation);
        generation.setBounds(280, 20, 100, 20);
        north.add(generation);

        map = new MapUI(game.map);

        frame.getContentPane().add(north, BorderLayout.NORTH);
        frame.getContentPane().add(map, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }

    public void view() {
        generation.setText("Generation : " + game.generation);
        map.repaint();
    }
}

public class LifeGame {
    public final Map map;
    public int generation;
    public boolean isStarted = false;

    public LifeGame(Map map) {
        this.map = map;
        generation = 0;
    }

    public void reset() {
        map.reset();
        generation = 0;
    }

    public void nextGeneration() {
        generation++;
        Map last = map.clone();
        for (int y = 0; y < map.height; y++) {
            for (int x = 0; x < map.width; x++) {
                int alives = last.countNeighborAlives(y, x);
                if (last.isDead(y, x) && alives == 3)
                    map.alive(y, x);
                else if (last.isAlive(y, x) && (alives == 2 || alives == 3))
                    map.alive(y, x);
                else
                    map.dead(y, x);
            }
        }
    }

    public void start() {
        isStarted = true;
    }

    public void stop() {
        isStarted = false;
    }

    public static void main(String args[]) throws InterruptedException {
        int height = 60;
        int width = 60;

        Map map = new Map(height, width);
        // map.alive(2,0);map.alive(5,0);
        // map.alive(2,1);map.alive(5,1);
        // map.alive(0,2);map.alive(1,2);map.alive(3,2);map.alive(4,2);map.alive(6,2);map.alive(7,2);
        // map.alive(2,3);map.alive(5,3);
        // map.alive(2,4);map.alive(5,4);
        // map.alive(0,5);map.alive(1,5);map.alive(3,5);map.alive(4,5);map.alive(6,5);map.alive(7,5);
        // map.alive(2,6);map.alive(5,6);
        // map.alive(2,7);map.alive(5,7);

        // map.alive(7,7);map.alive(7,6);map.alive(7,5);
        // map.alive(6,7);
        // map.alive(5,6);

        map.print();

        var game = new LifeGame(map);
        var ui = new LifeGameUI(game);
        ui.view();
        while (true) {
            if (game.isStarted) {
                game.nextGeneration();
                map.print();
                ui.view();
            }
            Thread.sleep(100);
        }
    }
}