How can I use math.random() with input character?

Question

For a school assignment I need to work with do/while/for loops(which suits the best) with randomized dice throws. The program stops once it throws a 6. But the output needs to look like the input char I give. I know that I need to use system.out.printf to format the output. It stops once the dice throws 6 characters. Would be great if someone could explain how and why too, so I can learn it for the next time.

Here's an example output:

# #
 #
# #

# #
 #
# #

#
 #
  #

# #
# #
# #

Code I have so far(also experimenting right now):

package com.company;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        System.out.println("What character do you want to use: ");

        String character = input.nextLine();

        char character2 = character.charAt(0);

        do{
            //math random probably needs to be put here?

            System.out.printf("%1s %2s\n",character2, character2); //formatting of output, not yet finished


        } while();
        //not sure if do while is better in this situation. For loops possible too?

    }
}

Answer 1

This is the basic flow that you need to follow:

do
  roll = random number between 1 and 6
  print the face of dice showing value of roll using selected character
while roll not 6

In Java you can use the nextInt(n) method of the Random class to get random numbers. One wrinkle is that it returns a number between 0 and n-1 inclusive, so you'll need to add 1 to the value returned, as in:

int roll = 1 + rand.nextInt(6);

As for printing the faces I would define each face this way, e.g. for 5:

String f5 = "x x\n x \nx x";

Then replace x with the character selected, ch, using f5.replace('x', ch).

You could even use an array to hold the faces, as in:

String[] faces = new String[6];
faces[0] = "  \n x \n   ";
<snip>
faces[6] = "x x\nx x\nx x";

Then in your loop you can do:

System.out.println(faces[roll-1].replace('x', ch));

Answer 2

To convert Math.random() into a die roll, multiply it by the number of possibilities, add the lowest possibility, and convert to int. There are six possibilities with a die. The lowest possibility is a 1. So we get:

(int) (Math.random()*6 + 1)

So, your loop would look like this:

int roll;
do {
    roll = (int) (Math.random()*6 + 1);

    // Display die
} while (roll != 6);

---

Now how do we display the die with the character the user gave? You mentioned using printf. With printf, %c is the format string for a character. 1$ means to use the first argument. %1$c over and over again would then print the first argument (which should be a char) over and over again.

Here's how to use xs with printf to display a roll of 6:

System.out.printf("%1$c %1$c\n%1$c %1$c\n%1$c %1$c\n", 'x');

So your loop would look like this:

int roll;
do {
    roll = (int) (Math.random()*6 + 1);

    switch (roll) {
        case 1: // printf a 1
                break;
        case 2: // printf a 2
                break;
        case 3: // printf a 3
                break;
        case 4: // printf a 4
                break;
        case 5: // printf a 5
                break;
        case 6: System.out.printf("%1$c %1$c\n%1$c %1$c\n%1$c %1$c\n", character2);
                break;
    }
} while (roll != 6);

Answer 3

You can use this as an output with if else, just take the random number that created by Math.Random();.

if (YOURRANDOMNUMBER== 1) {
    System.out.println("* * * * *");
    System.out.println("*       *");
    System.out.println("*   #   *");
    System.out.println("*       *");
    System.out.println("* * * * *");
}

if (YOURRANDOMNUMBER== 2) {
    System.out.println("* * * * *");
    System.out.println("*    #  *");
    System.out.println("*       *");
    System.out.println("*  #    *");
    System.out.println("* * * * *");
}
if (YOURRANDOMNUMBER== 3) {

    System.out.println("* * * * *");
    System.out.println("*    #  *");
    System.out.println("*   #   *");
    System.out.println("*  #    *");
    System.out.println("* * * * *");
}

if (YOURRANDOMNUMBER== 4) {
    System.out.println("* * * * *");
    System.out.println("*  # #  *");
    System.out.println("*       *");
    System.out.println("*  # #  *");
    System.out.println("* * * * *");
}

if (YOURRANDOMNUMBER== 5) {

    System.out.println("* * * * *");
    System.out.println("*  # #  *");
    System.out.println("*   #   *");
    System.out.println("*  # #  *");
    System.out.println("* * * * *");
}
if (YOURRANDOMNUMBER== 6) {

    System.out.println("* * * * *");
    System.out.println("*  # #  *");
    System.out.println("*  # #  *");
    System.out.println("*  # #  *");
    System.out.println("* * * * *");
    System.exit(0);
    }

Its termitate the program when you go in YOURRANDOMNUMBER== 6