Looking to Create a Randomized Array using Java

Question

I'm building out a user defined array as a game board. The characters used "O" and "." have to be randomized and the "O" has to appear more than once.

This is what I have thus far.

import java.util.Scanner;


public class PacMan {

    public static void main(String[] args) 
    {


        Scanner input = new Scanner(System.in);
        System.out.println("Input total rows:");
        int row = input.nextInt();
        System.out.println("Input total columns:");
        int column = input.nextInt();



        boolean[][] cookies = new boolean[row+2][column+2];
        for (int i = 1; i <= row; i++)
            for (int j = 1; j <= column; j++);
                cookies [row][column] = (Math.random() < 100);

        // print game
        for (int i = 1; i <= row; i++) 
        {
            for (int j = 1; j <= column; j++)
                if (cookies[i][j]) System.out.print(" O ");
                else             System.out.print(". ");
            System.out.println();
        }
    }
}

The output, for example, produces a 5 x 5 grid, but the "O" only appears once and is at the bottom right of the grid.

Assistance randomizing the "O" and "." and having the "O" appear in random fashion throughout the board which is initialized by the user input via Scanner.

Here is the updated code which is producing the output that I'm looking for and is user defined.

import java.util.*;
public class PacManTest
{
    public static void main(String[] args)
    {
        char O;
        Scanner input = new Scanner(System.in);
        System.out.println("Input total rows:");
        int row = input.nextInt();
        System.out.println("Input total columns:");
        int column = input.nextInt();

        char board[][] = new char[row][column];

        for(int x = 0; x < board.length; x++)
        {
            for(int i = 0; i < board.length; i++)
            {
                double random = Math.random();
                if(random >.01 && random <=.10)
                {
                    board[x][i] = 'O';
                }

                else {
                    board[x][i] = '.';
                }
                System.out.print(board[x][i] + " ");
            }
            System.out.println("");
        }
    }
}

Possible duplicate of Java random array of numbers

K.Nicholas
– K.Nicholas

2017-07-05 20:38:42 +00:00
Commented Jul 5, 2017 at 20:38 — K.Nicholas
– K.Nicholas, Commented Jul 5, 2017 at 20:38

001 · Accepted Answer · 2017-07-05 20:56:26Z

2

The main issue is the typo in the first loop:

cookies [row][column] = (Math.random() < 100);

should be

cookies [i][j] = (Math.random() < 100);

Second, Math.random() returns a value greater than or equal to 0.0 and less than 1.0 (doc). So, (Math.random() < 100); will always be true. If you want a 50% chance of an O or . use:

cookies[i][j] = Math.random() < 0.5;

Also, not sure what your motivation is for using a starting index of 1 but array indexes start at 0.

answered Jul 5, 2017 at 20:56

001

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3 Comments

Joshua Peterson Over a year ago

Johnny thanks. So I've actually managed to make implementations to create what I'm looking for.

Joshua Peterson Over a year ago

Now that I've constructed the user defined game board with randomized "O" characters which act as cookies for the player defined as "<" to move across the board to "eat" those cookies. I need to figure out how to get the character on the board, initially open face facing left ">" and has the ability to move across the board using user defined movements. This will create symbols ">", "V", "<", and "^" depending on the user move.

001 Over a year ago

@JoshuaPeterson Create a class for the player that stores its current row, column, direction. Then you need a loop to read the keyboard and move the player based on user input.

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