Java implementation of Conway's Game of Life with GUI

Question

I've implemented the Conway's Game of Life in Java, including a GUI. Here's the code of the two classes I wrote:

GameOfLife.java

public class GameOfLife {
 public static void main(String[] args) throws InterruptedException {
 Gui gui = new Gui();
 int [][] array = new int [71][71];
 //Field edge is getting filled up with '2'
 for(int i = 0; i < array.length; i++){
 for(int j = 0; j < array.length; j++){
 array[i][j] = 2;
 }
 }
 //Field gets filled up with '0' = dead cells
 for(int i = 1; i < array.length - 1; i++){
 for(int j = 1; j < array.length - 1; j++){
 array[i][j] = 0;
 }
 }
 //A glider
 array[9][5]=1;
 array[9][6]=1;
 array[9][7]=1;
 array[8][7]=1;
 array[7][6]=1;
 Gui.printingOut(array);
 }
 public static void applyRules(int[][] array) {
 int[][] newArray = new int[array.length][array.length];
 for(int y = 1; y < array.length - 1; y++) {
 for(int x = 1; x < array.length - 1; x++) {
 int neighbors = neighborsCounter(array, x, y);
 if(array[x][y] == 1) {
 if((neighbors < 2) || (neighbors > 3)) {
 newArray[x][y] = 0;
 }
 if((neighbors == 2) || (neighbors == 3)) {
 newArray[x][y] = 1;
 }
 }
 else if(array[x][y] == 0){
 if(neighbors == 3) {
 newArray[x][y] = 1;
 }
 else {
 newArray[x][y] = 0;
 }
 }
 }
 }
 for(int i = 1; i < array.length - 1; i++){
 for(int j = 1; j < array.length - 1; j++) {
 array[i][j] = newArray[i][j];
 }
 }
 }
 public static int neighborsCounter(int[][] array, int x, int y) {
 int neighbors = 0;
 for(int i = x - 1; i <= x + 1; i++) {
 for(int j = y - 1; j <= y + 1; j++) {
 if(array[i][j] == 1) {
 neighbors = neighbors + 1;
 }
 }
 }
 if(array[x][y] == 1) {
 neighbors = neighbors - 1;
 }
 return neighbors;
 }
}

And here's the class for the GUI: Gui.java

import javax.swing.*;
import java.awt.*;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
public class Gui {
 static JPanel panel;
 static JFrame frame;
 static int count = 0;
 static boolean[] test = new boolean[1];
 public static void helper() {
 count++;
 if(count % 2 != 0) {
 test[0] = false;
 }
 else {
 test[0] = true;
 }
 }
 public static void GraphicalInterface(int[][] array, Graphics graphic) {
 int BOX_DIM = 10;
 for (int i = 0; i < array.length; i++) {
 for (int j = 0; j < array[0].length; j++) {
 if(array[i][j] == 0) {
 graphic.setColor(Color.WHITE);
 }
 if(array[i][j] == 1) {
 graphic.setColor(Color.BLACK);
 }
 if(array[i][j] == 2) {
 graphic.setColor(Color.RED);
 }
 graphic.fillRect(i * BOX_DIM, j * BOX_DIM, BOX_DIM, BOX_DIM);
 }
 }
 }
 public static void printingOut(int[][] array) throws InterruptedException {
 test[0] = true;
 JFrame frame = new JFrame("Conway's Game of Life");
 frame.setSize(830,800);
 frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
 JPanel panel = new JPanel();
 panel.setPreferredSize(new Dimension(710, 710));
 JButton button = new JButton("Start / Stop");
 button.addActionListener(new ActionListener()
 {
 public void actionPerformed(ActionEvent e) {
 helper();
 }
 });
 frame.add(button, BorderLayout.EAST);
 frame.add(panel, BorderLayout.WEST);
 frame.setVisible(true);
 while(true) { 
 //Printing out
 while(Gui.test[0]) {
 Graphics graphic = panel.getGraphics();
 GraphicalInterface(array, graphic);
 //Applying rules
 GameOfLife.applyRules(array); 
 Thread.sleep(249); 
 }
 Thread.sleep(1); 
 }
 }
}

I would appreciate any suggestions to improve my code.

Answer 1

Gui.java

1) The panel and frame variables are unused.

 static JPanel panel;
 static JFrame frame;

2) The test variable can be converted to a boolean.

 static boolean test;

3) The helper method can be simplified

 public static void helper() {
 test = count++ % 2 == 0;
 }

4) Method GraphicalInterface

• You should rename it to graphicalInterface, since the methods start with a lowercase.

• The variable BOX_DIM should be a class constant.

 public static final int BOX_DIM = 10;

• In the loop, you can use an else-if or a switch case, since you can have only one choice.

if (array[i][j] == 0) {
 graphic.setColor(Color.WHITE);
} else if (array[i][j] == 1) {
 graphic.setColor(Color.BLACK);
} else if (array[i][j] == 2) {
 graphic.setColor(Color.RED);
}

or

if (array[i][j] == 0) {
 graphic.setColor(Color.WHITE);
} else if (array[i][j] == 1) {
 graphic.setColor(Color.BLACK);
} else if (array[i][j] == 2) {
 graphic.setColor(Color.RED);
}

GameOfLife.java

Method applyRules

1) Since the array is not updated during the execution of the method, I suggest that you extract the array.length in a variable (used 6 times).

2) You can extract array[x][y] in a variable.

 public static void applyRules(int[][] array) {
 final int lengthOfTheArray = array.length;
 int[][] newArray = new int[lengthOfTheArray][lengthOfTheArray];
 for (int y = 1; y < lengthOfTheArray - 1; y++) {
 for (int x = 1; x < lengthOfTheArray - 1; x++) {
 int neighbors = neighborsCounter(array, x, y);
 final int currentArrayValue = array[x][y];
 if (currentArrayValue == 1) {
 if ((neighbors < 2) || (neighbors > 3)) {
 newArray[x][y] = 0;
 }
 if ((neighbors == 2) || (neighbors == 3)) {
 newArray[x][y] = 1;
 }
 } else if (currentArrayValue == 0) {
 if (neighbors == 3) {
 newArray[x][y] = 1;
 } else {
 newArray[x][y] = 0;
 }
 }
 }
 }
 for (int i = 1; i < lengthOfTheArray - 1; i++) {
 for (int j = 1; j < lengthOfTheArray - 1; j++) {
 array[i][j] = newArray[i][j];
 }
 }
 }

Method neighborsCounter

1) Instead of increasing the variable neighbors using neighbors = neighbors + 1;, you can use neighbors++;.

2) Same for the decrease, you can use:

if (array[x][y] == 1) {
 neighbors--;
}
``

Answer 2

You should remove all static qualifiers, so that you have real object. Maby create a Main.java with the main function so that it is your only class with static. Your distinction between Gui and GameOfLife is good and i would keep it that way. You can move the int [][] array = new int [71][71]; out of the method to a field from the class GameOfLife and you should rename it to something like "gamefield" or "gamestate". These are the important things.

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A little thing you can replace:

static int count = 0;
static boolean[] test = new boolean[1];

with something like:

boolean running = true;

the hole helper() can be replaced with:

running = !running;