This exercise demonstrates the nature of 3 dimensional arrays. It might be helpful to think of them as an indexed box, rather than 3 lists.

MultiDimArray.java

import java.util.Random;
import java.util.Scanner;

public class MultiDimArray {
    static Random rand = new Random();
    static int count = 0;

    public static void main(String[] args) {

        // 3-D array with fixed length:
        System.out.println("This program demonstrates the breadth of 3-dimensional arrays.");
        System.out.println("You pick each array size, and the program will assign a number");
        System.out.println("to each point in the 3 dimensional array.");
        System.out.println("Lets get started:");
        System.out.println("How many items do you want in the first array?");
        int a = enterANumber();
        System.out.println("How many in the 2nd array?");
        int b = enterANumber();
        System.out.println("How many in the 3rd?");
        int c = enterANumber();

        int[][][] point = new int[a][b][c];
        for(int i = 0; i < point.length; i++)
            for(int j = 0; j < point[i].length; j++)
                for(int k = 0; k < point[i][j].length; k++)      {
                    ++count;
                    point[i][j][k] = count;
                }
        for(int i = 0; i < point.length; i++)
            for(int j = 0; j < point[i].length; j++)
                for(int k = 0; k < point[i][j].length; k++)
                    System.out.println("a2[" + (i+1) + "][" + (j+1) + "][" +
                            (k+1) + "] = " + point[i][j][k]);
    }


    public static int enterANumber() {
    Scanner in = new Scanner (System.in);
    return Integer.parseInt(in.next());
    }