Thread: Help with my game of life program

Hi,
Thanks for replying. Would I need to define them at the top of my program, where I have defined int[][] grid?
(Might sound stupid that question above, but I am very new to Java)

Thanks
An will do highlight code

What are those variables used for? Do any other methods need to see them?
Does their value need to be save past the end of the method where they are used?
If they are only used in one method, then define them inside of the method.
If other methods need to access them, then define them outside of the method as class variables.

The variables are use used to display the run() method but I not sure if is how to do it. (What I'm basically trying to with that command is to display my run() method using the show() method.
They need to be repeated to constantly show the different generations. They are used in one method and need to be called/accessed by another method in the same class.
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I have changed the "lifegrid" class (below) as follows so that the run() method will be displayed using the show() method and ultimately the game of life should be displayed. Everything compiles fine but, nothing appears on the command line except blank lines. (Its like the program is running but nothing is displayed does anyone know why this happens.)

import java.util.Scanner; 
import javax.swing.*;
import java.io.File;
import java.io.FileNotFoundException;
 
public class lifegrid
{
    int[][] grid;
    boolean[][] old;
    boolean[][] New;
    boolean[][] swap; 
 
    lifegrid(int x, int y,String filename )throws FileNotFoundException {grid = new int[y][x]; File file = new File(filename); 
    Scanner scanner = new Scanner (file); 
    int i = 0; 
    int j = 0;
 
    while (scanner.hasNextLine()){
	while (scanner.hasNext()){
	    if (scanner.next().equals("*"))
		grid[i][j] = 1;	    
else
    grid[i][j] = 0;
    i++; 
}
    j++; 
    } 
}
 
    public int getX() {return grid[0].length;}
    public int getY() {return grid.length;}
    public int getCell(int x, int y) {return grid[y][x];}
    public void setCell(int x, int y, int v) {grid[y][x] = v;}
 
 
    public void show()
    {
	for (int r = 0; r < getX(); r++){
	    for (int s = 0; s < getY(); s++)
		System.out.println(grid[r][s]);
	}		
	System.out.println("Generations: " + run(old,New,swap));
    }
    public static int neighbours(int x, int y, boolean[][] grid)
{
	int count = 0;
	if (x > 0){
	    if (grid[x-1][y])
		count++;
		 }
	if (x < x-1){
		if (grid[x+1][y])
		    count++;
	    }
	if (grid[x][y-1]){
	    count++;
	}
	if (grid[x][y+1]){
	    count++;
	}
	if ((x > 0) && (y > 0)){
	    if (grid[x-1][y-1])
		count++;
	}
	if (x > 0){
	    if (grid[x-1][y+1])
		count++;
	}
	if (x < x-1){
	    if (grid[x+1][y-1])
		count++;
	}
	if ((x < 0) && (y < 0)){
	    if (grid[x+1][y+1])
		count++;
		}
	return count;
}
    public boolean[][] run(boolean[][] old, boolean[][] New, boolean[][] swap)
{
    	for (int x = 1; x < old.length - 1 ; x++){
	    for (int y = 1; y < old.length - 1; y++){
		if (neighbours (x, y, old) == 3)
		    old[x][y] = true;
		if (neighbours (x, y, old) < 2)
		    old[x][y] = true; 
		if (neighbours (x, y, old) > 3)
		    old[x][y] = false; 
	    }
	}
	for (int i = 0; i < old.length; i++){
	    for (int j = 0; j < old.length; j++){
		old[i][j] = New[i][j];
	       		    }
	    return New;
	}
//Prints Generations    
	for (int x = 0; x < swap.length; x++){
	    for (int y = 0; y < swap.length; y++){
		if (swap[x][y] = true){
		    System.out.print("[*]");
	     	    if (swap[x][y] = false){
			System.out.print("[]");
		    }		 
		}
	    }
	    return swap;
	}
	return old;
}
}

BTW this is what I am trying to do:5. Add a method run() which computes successive generations and prints
them using your show() method. You will need to maintain two grids:GUI interface 191
the original and the new. We suggest you have three grid variables old,
new and swap and two actual grids which are swapped at the end of each
generation.

nothing appears on the command line except blank lines.

You should be seeing something besides blank lines.
Add some text to your print outs to see what they are doing. Something like this.
System.out.println("r=" + r + ", s=" + s + ", grid=" + grid[r][s]);

Add some more printlns to show where the execution is going.

Would anyone know I can incorporate a GUI into my program so that the gameoflife is shown/pops up in a separate window (as a GUI).

Thanks for the help you've given me norm I appreciate it.

A GUI starts with a JFrame. Then you add panels to that and and more components to those panels.

I have writen the game of life algorithm but I just need to add the GUI. I've tryed to add the GUI using a JFrame but I get errors saying cannot find symbol errors.

class TFrame
 extends JFrame
{
 TFrame()
 {
   setTitle("Game of Life");
   setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   setVisible(true);
 }
}

I Added this piece of code above and get a cannot find symbol error.

import java.util.Scanner;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.Color;
import java.io.File;
import java.io.FileNotFoundException;
import java.awt.*;
import java.awt.event.*;
 
public class life {
 
	public int[][] grid;
	public int[][] grid2;
	int currentGeneration = 0;
	int x, y;
	String filename;
        public int count = 0;
 
	public static void main(String[] args) throws FileNotFoundException {
		life lifegrid = new life(6, 10, "testLab8.lif");
		lifegrid.show();
	}
 
		life(int x, int y, String filename) throws FileNotFoundException {
 
		this.grid = new int[x][y];
		File file = new File(filename);
		Scanner keyboard = new Scanner(file);
		String line;
		int lines = 0;
 
		while (keyboard.hasNextLine()) {
			line = keyboard.nextLine();
			int i = 0;
			for (i = 0; i < line.length(); i++) {
				if (line.charAt(i) == '*') {
					grid[lines][i] = 1;
				} else {
					grid[lines][i] = 0;
				}
			}
			lines++;
		}
	}
    public int getX() {return grid[0].length;}
    public int getY() {return grid.length;}
    public int getCell(int y, int x) {return grid[x][y];}
    public void setCell(int y, int x, int v) {grid[x][y] = v;}
 
    public void show()
 {
     for (int x = 0; x < getY(); x++) {
	 for (int y = 0; y < getX(); y++) {
	      System.out.print(grid[x][y]);
	      /* if (getCell(x, y) == 1){
		 livingCells.setColor(Color.black);
		 livingCells.fillRect(x * 4, y * 4, 4, 4);
	     }
	     else {
		 livingCells.setColor(Color.white);
		 livingCells.fillRect(x * 4, y * 4, 4, 4);
		 }*/
	 }
     }
 }
 
    public int neighbours(int x, int y) {
	    int count = 0;
	if (x > 0){
	    if (grid[x][y] == grid[x-1][y])
		count++;
		 }
	if (x < x-1){
		if (grid[x][y] == grid[x+1][y])
		    count++;
	    }
	if (grid[x][y] == grid[x][y-1]){
	    count++;
	}
	if (grid[x][y] == grid[x][y+1]){
	    count++;
	}
	if ((x > 0) && (y > 0)){
	    if (grid[x][y] == grid[x-1][y-1])
		count++;
	}
	if (x > 0){
	    if (grid[x][y] == grid[x-1][y+1])
		count++;
	}
	if (x < x-1){
 	    if (grid[x][y] == grid[x+1][y-1])
		count++;
	}
	if ((x < 0) && (y < 0)){
	    if (grid[x][y] == grid[x+1][y+1])
		count++;
		}
	return count;
			}
 
 public void run()
    {
     for (int x = 1; x < getY(); x++){
	 for (int y = 1; y < getX(); y++){
		if (neighbours (y, x) == 3){
		    if  (neighbours (y, x) < 2 || neighbours(x, y) > 3){
			    setCell(y, x, 1);
				}
		    else {
			setCell(x, y, 0);
		    }
		}
		else {
		    if (neighbours(x, y) ==3) {
			setCell(x, y, 1);
		    }
		    else {
			setCell(x, y, 0);
		    }
		}
	    }
	}
    for (int i = 0; i < getY(); i++) {
	for (int j = 0; j < getX(); j++){
	    grid[y][x] = grid2[y][x];
	}
    }
      currentGeneration++;
    }    
}

I get errors saying cannot find symbol

Please copy and paste here the full text of the error messages if you want help with them.