Thread: Can't run Game of Life programm

Hello guys, I'm new here, I was trying my homework for computer science which consists of making a basic Game of Life program with a 2D boolean array and a Random number with a seed, this is what I have so far:

import java.util.*;
public class Life 
{
	static Scanner console = new Scanner(System.in);
 
	/**
	 * @param args
	 */
	public static void main(String[] args) 
	{
 
		//String file = null;
		Scanner input;
		if(args.length > 0)
		{
			//file = args[0];
		}
		else
		{
		    System.out.println("Enter number of rows flowed by number of columns and a seed: ");
			//file = console.next();
		}
		input = new Scanner(console.next());
		boolean [][] matrix = readInput(input);
		System.out.println(matrix.length + " " + matrix[0].length);
		printMatrix(matrix);
 
	}
 
	/**
	 * reads the input already entered by user
	 * 
	 */
	private static boolean[][] readInput(Scanner input)
	{
		int numRows;
		int numCols;
		Random ran = new Random();
 
		String message1= "Please enter number of rows, columns, and a seed in that specific order";
		try
		{
			numRows = input.nextInt();
			numCols = input.nextInt();
			ran.setSeed(input.nextLong());
			if (numRows + numCols < 9)
			{
				System.out.println("Not enough space for an organism to survive, try again");
			}
			boolean[][] matrix = new boolean[numRows][numCols];
			createMatrix(matrix);
			for(int row = 1; row < matrix.length - 1; row ++ )
			{
				for( int col = 1; col < matrix[row].length - 1; col++)
				{
 
					matrix[row][col] = ran.nextBoolean();
 
				}
			}
			return matrix;
		}
		catch(NoSuchElementException e)
		{
			throw new IllegalStateException(message1);
		}
 
	}
 
 
	/**
	 * Prints the matrix including the toxic border
	 * 
	 */
	private static void printMatrix(boolean[][] matrix)
	{
		for(int r = 0; r < matrix.length; r++)
		{
			for(int c = 0; c < matrix[r].length; c++)
			{
				System.out.println(matrix[r][c] + " ");
			}
			System.out.println();
		}
		System.out.println();
 
	}
 
	/**
	 * Initializes a matrix by setting the array's entire content to false
	 * @param matrix
	 */
	private static void createMatrix(boolean[][] matrix)
	{
		for(int r = 0; r < matrix.length; r++)
		{
			for(int c = 0; c < matrix[r].length; c++)
			{
				matrix[r][c] = false;
			}
 
		}
 
	}
 
 
}

when I run it and enter the 3 inputs it just gives me the IllegalStateException and I have no idea why, please help

you have used two Scanner objects and second object has only one character read from first object it doesn't have 3 characters
to resolve your problem use just first object when calling readInput(console) method.

Wow thank you very much, also on my printMatrix method the output should be a '-' for false and a '#' for true, any ideas how I can do this?
Again thank you a lot

output should be a '-' for false and a '#' for true

The tri compare statement could work:
String val = (boolean ? "#" : "-");

ok so I changed the printMatrix method to look like this

private static void printMatrix(boolean[][] matrix)
	{
		for(int r = 0; r < matrix.length; r++)
		{
			for(int c = 0; c < matrix[r].length; c++)
			{
				if(matrix[r][c] = false)
				{
					System.out.println( "#");
				}
				else
				{
					System.out.println("-");
				}
			}
			System.out.println();
		}
		System.out.println();
 
	}

I should be getting an output that looks like this:
– – – – – – – –
– # # # – – – –
– # # # # – # –
– – – # # – # –
– # – # – ## –
– – – – – – – –

instead of that I'm getting straight-down '–' , any ideas why?

if(matrix[r][c] = false)
That is an assignment statement not a comparison.

You do NOT need to compare the value of a boolean. Use its value directly:
if(!matrix[r][c])

Hello again guys, I was cleaning up my code and doing tests and I wanted to ask if you recommend any way to stop the program if only 2 inputs are typed, like throwing an exception if the user only enters the number of rows and columns,
Thanks in advance

You can use the Scanner's has... method to detect if there is any input to read.
Will that allow you to detect that the user has not entered all the input you want?
Try it and see what the effect is.

I tried it and the program just waits for a third input, after a third input its when the program stops, I guess making it so it stops at 2 inputs would not matter

Can you explain what your problem is now?

Its not really a problem, I was just trying to create an if loop trying to stop the program after just 2 inputs, but when I run the program and I write just 2 numbers, it just continues running waiting for me to enter a third digit, this is what I wrote:

if(console.hasNextInt())
{
numRows = console.nextInt();
numCols = console.nextInt();
casual.setSeed(console.nextLong());
}
else
{
 throw new IllegalStateException(message1);
}

I entered 7 8 as input, pressed Enter and the programs just stays waiting for a third digit, I'm tying to make it so it produces a message saying that the user needs to enter one last number

I don't know if there is an easy way to exit from a next method that is waiting for user input.
What if you ask separately for each of the inputs so the user knows what the next number to be entered should be?

Great idea, I'll try it out, thanks much

so now my program needs to read the parameters from standard input. The new inputs for this part are the values for the ranges, birthLow, birthHigh, liveLow, and liveHigh. I need to read the matrix like before and then repeat for five iteration of updating the matrix and printing the result.

I need to calculate the number of entities in the neighborhood and compare the count with the birth range (if the cell is empty) or live range (if there was already an entity there) the count must be based on the values as of the previous iteration. I will need to make a copy of the matrix before doing the updates so that I can count entities in neighborhoods based on original values.
I am completely lost and I wrote some stuff that a friend explained but I don't even know if its right, please please help!!!!
here's what I have:

* Simple I/O of the Game of Life
 * @author Eddy Guzman (edguzman@marauder.millersville.edu)
 *
 */
import java.util.*;
public class Life 
{
 
 
	/**
	 * Our main method, the user enters the number of rows followed by the number of columns and the seed
	 * @param args
	 */
	public static void main(String[] args) 
	{
	    Scanner console = new Scanner(System.in);
		System.out.println("Enter number of rows followed by number of columns and a seed: ");
		boolean [][] matrix = readInput(console);
		printMatrix(matrix);
		nextMatrix(matrix);
 
	}
 
	/**
	 * 
	 * Reads the input already entered by user. If the space available in the grid is not enough
	 * for an organism to survive, the program will throw an IllegalStateException
	 * Returns the matrix array after all the 3 inputs have been entered.
	 * 
	 */
	private static boolean[][] readInput(Scanner console)
	{
		int numRows;
		int numCols;
		Random casual = new Random();
		String message1= "Please enter number of rows, columns, and a seed in that specific order";
		try
		{
 
			numRows = console.nextInt();
			numCols = console.nextInt();
			if (numRows + numCols < 9)//this is to check that there is space for an organism to survive
			{
 
				throw new IllegalStateException("Not enough space for an organism to survive, try again");
 
			}
			casual.setSeed(console.nextLong());
			System.out.println();
			boolean[][] matrix = new boolean[numRows][numCols];
 
			createMatrix(matrix);
			for(int row = 1; row < matrix.length - 1; row ++ )
			{
				for( int col = 1; col < matrix[row].length - 1; col++)
				{
 
					matrix[row][col] = casual.nextBoolean();
 
				}
			}
 
			return matrix;
		}
		catch(NoSuchElementException e)
		{
			throw new IllegalStateException(message1);
		}
		catch (StringIndexOutOfBoundsException e) 
		{
			throw new IllegalStateException(message1);
		}
 
	}
 
 
	/**
	 * Prints the matrix including the deadly border
	 * @param matrix - uses the values in the matrix to print it
	 */
	private static void printMatrix(boolean[][] matrix)
	{
		System.out.println("Here's the matrix");
		for(int r = 0; r < matrix.length; r++)
		{
			for(int c = 0; c < matrix[r].length; c++)
			{
				if(!matrix[r][c])
				{
					System.out.print( " – " );
				}
				else
				{
					System.out.print(" # ");
				}
			}
			System.out.println();
		}
		System.out.println();
 
	}
 
	/**
	 * Initializes a matrix by setting the array's entire content to false
	 * @param matrix - uses the length of the matrix to set it all to false
	 */
	private static void createMatrix(boolean[][] matrix)
	{
		for(int r = 0; r < matrix.length; r++)
		{
			for(int c = 0; c < matrix[r].length; c++)
			{
				matrix[r][c] = false;
			}
 
		}
 
	}
 
	/**
	 * 
	 * @param matrix
	 */
	private static void nextMatrix(boolean[][] matrix)
	{
		boolean [][] newMatrix = matrix.clone();
		for (int row = 1; row < matrix.length; row++)
		 {
		       for (int col = 1; col < matrix.length; col++)
		       {
 
		        newMatrix[row][col] = matrix[row][col];
 
		        int count = countNeighbors ( newMatrix , row, col );
 
		        switch (count)
		        {
		            case 0: case 1:
		                    newMatrix[row][col]=false;
		                break;
 
		            case 2: 
		                if(newMatrix[row][col])
		                {
		                	newMatrix[row][col] = true;
		                }
 
 
		                if(!newMatrix[row][col])
		                {
		                	newMatrix[row][col]=false;
		                }
 
		                break;
 
		            case 3:
		                    newMatrix[row][col]=true;
		                break;
 
		            case 4: case 5: case 6: case 7: case 8:
		                newMatrix[row][col]=false;
		                break;
		         }
 
		        matrix [row][col] = newMatrix[row][col];
		        }
		    }
 
	}
 
	/**
	 * 
	 * @param newMatrix
	 * @param row
	 * @param col
	 * @return
	 */
 
	private static int countNeighbors(boolean[][] matrix, int row, int col)
	{
 
		int ncount = 0;
        for(int r = row - 1; r <= row+1; r++) 
        {
            if(row < 0 || row >= matrix.length ) 
            {
                continue;
            }
            for(int c = col - 1; c <= col + 1; c++) 
            {
                if(col < 0 || col >= matrix.length || (r == row && c == col)) 
                {
                    continue;
                }
                if(matrix[row][col]) 
                {
                    ncount++;
                }
            }
        }
        return ncount;
    }
 
 
 
}

Take it one step at a time.
Do you have it going through the 5 cycles yet?
Get that working before trying to save and display the statistics.

that's one of my question, do I have to do the console.nextInt() in the same readInput method, or do I need to create a new one?

A suggestion for testing.
Forget about getting input from the user until you get the program's logic working. Hard code some good testing values for now:
numRows = 8; //console.nextInt();
numCols = 8; //console.nextInt();

ok but where should I initialize the other 5 variables?

What other 5 variables?

the ranges: birthLow, birthHigh, liveLow, and liveHigh 4 in total my mistake
For a birth to occur, the cell must be empty and the neighborhood density be in the birth range. The birth range can be given as two integers from zero to nine, birthLow and birthHigh, so that a birth will occur if the cell is empty and the neighborhood population is at least birthLow and no more than birthHigh. Similarly, a death occurs in a cell if there is an organism there and the neighborhood has less than the minimum population for survival, or greater than the maximum. Hence there is a live range provided as two integers from zero to nine, liveLow and liveHigh.

Are any of those variables in the code you posted?
I only see three places where you read in data from the user.

that's one place I'm having trouble with, I'm not sure where I need to use them

You need to read the assignment again.
Also go to wikipedia and read about the Game of Life so you understand what the program is supposed to do.