DnD Dice Roll Simulation

Question

I am Trying to make a simulated dice rolling game for my friends. I want to utilize two classes Dice and a child class VarDice which will let user choose how many sides. However, I am struggling to get my derived class to work properly.

This is my parent class :

import java.util.Random;

public class Dice {
   
   protected int numRolled;
   final Random rand = new Random();
    
    
   public void roll() {
        numRolled = rand.nextInt(5) + 1;
   }
   public int getNumRolled() {
      return numRolled;
   }
   
}

This is the derived class:

    import java.util.Random;
    
    
    public class VarDice extends Dice {
    
       public static void main(String[] args) {
            Scanner scnr = new Scanner(System.in);
            int numSides;
            
            public void setNumSides(int sides) {
                numSides = sides;
            }
            
           public int getNumSides() {
              return numSides;  
            }
            
            @Override
            public void roll() {
            numRolled = rand.nextInt(numSides) + 1;
           }
    
    }
    }

This is finally my main code:

import java.util.Scanner; 

    public class Main {
    
       public static void main(String[] args) {
            Scanner scnr = new Scanner(System.in);
             int numSides;

             VarDice dice = new VarDice();

             numSides = scar.nextInt();

             dice.setNumSides(numSides);
             
             dice.roll();
             System.out.println("The dice come up " + dice.getNumRolled()); 
        
    
        }
    
    }

I want the user to be able to input how many sides are on their dice and how many dice, but my VarDice class is not overriding the roll method very well and I am a little bit lost on the errors I am getting... I appreciate the help and hope the format is appropriate.

Answer 1

A few mistakes I noticed:

the line numSides = scar.nextInt(); should be numSides = scnr.nextInt();

the class VarDice has wrapped everything in public static void main(String[] args) {...}. Remove this wrapping to ensure that the code is a part of the class and not the method.

With those changes, the code worked for me.

Answer 2

There are some problems, here:

1. The code of VarDice is in a main method that doesn't belong here.
2. As @Bohemian pointed out in the comments, you don't really need two classes with inheritance, here. I'd drop the parent class, because the default case of 6 sides can be handled by a default constructor.
3. And yes, @Bohemian, "Dice" is the plural of "Die".

Your Die class could look something like this:

import java.util.Random;

public class Die {
    private final Random rand;
    private int numSides;
    private int numRolled;

    public Die(int numSides) {
        this.rand = new Random();
        this.numRolled = -1;
        // custom no. of sides, 6 if invalid
        this.numSides = numSides > 0 ? numSides : 6;
    }

    public Die() {
        this(6); // 6 is default
    }

    public void setNumSides(int sides) {
        numSides = sides;
        numRolled = -1;
    }

    public int getNumSides() {
        return numSides;
    }

    public int getNumRolled() {
        if (numRolled < 0) {
            roll();
        }
        return numRolled;
    }

    public int roll() {
        numRolled = rand.nextInt(numSides) + 1;
        return numRolled;
    }
}

And you'd use this class something like this in your application:

import java.util.Scanner;

public class App {

    public static void main(String[] args) {
        // use default die
        Die die = new Die(); // create instance with default no of sides
        System.out.println(die.roll()); // roll die and print result
        System.out.println(die.getNumRolled()); // print rolled number again
        // use custom die
        Scanner scanner = new Scanner(System.in);
        System.out.print("Set number of sides (greater than 0): ");
        Die customDie = new Die(scanner.nextInt());
        System.out.println(customDie.roll()); // roll custom die
        scanner.close();
    }

}