Question

Using the Die class defined in Chapter 4, write a class called TwoDice, composed of two Die objects. Include methods to set and get the individual die values, a method to roll the dice, and a method that returns the current sum of the two die values. Include a static main method in TwoDice so that it can instantiate and use a TwoDice object to illustrate all the features in the class.

Answer 1

Input:

TwoDice.java

import java.util.Scanner;

public class TwoDice { //Define a class TwoDice
    private Die die1 = new Die(); //Create an object of class Die
    private Die die2 = new Die();

    void setDie1(int value) //Set value for Die
    {
        if(!die1.setValue(value)) //Check if value is set
            System.out.println("Value should be between 1-6");
    }

    void setDie2(int value)
    {
        if(!die2.setValue(value))
            System.out.println("Value should be between 1-6");
    }

    int getDie1() //Get value for die
    {
        return die1.getValue();
    }

    int getDie2()
    {
        return die2.getValue();
    }

    void rollDice() //Roll the dice
    {
        setDie1((int) (Math.random() * 6) + 1); //Set a random value between 1 - 6
        setDie2((int) (Math.random() * 6) + 1);
    }

    int getSum(){
        return getDie1() + getDie2(); //Return addition of die faces
    }

    public static void main(String[] args)
    {
        TwoDice dice = new TwoDice(); //Create an object of TwoDice
        Scanner scanner = new Scanner(System.in); //Initialize scanner for accepting input
        String ans = "y"; //Initialize a string for loop
        while (ans.equals("y"))
        {
            System.out.println("1.Roll Dice\n2.Set Values\n3.Get Values"); //Display Menu
            int choice = scanner.nextInt(); //Ask user to enter choice
            switch (choice) //Switch case for choice
            {
                case 1:
                    dice.rollDice();
                    System.out.println("Die 1: "+dice.getDie1()+" | Die 2: "+dice.getDie2());
                    System.out.println("The sum is "+dice.getSum());
                    break;
                case 2:
                    System.out.println("Enter value for Die 1");
                    dice.setDie1(scanner.nextInt());
                    System.out.println("Enter value for Die 2");
                    dice.setDie2(scanner.nextInt());
                    break;
                case 3:
                    System.out.println("Die 1: "+dice.getDie1()+" | Die 2: "+dice.getDie2());
                    break;
                    default:
                        System.out.println("Wrong choice!");
                        break;
            }
            System.out.println("Do you want to continue?(y/n)");
            ans = scanner.next();
        }
    }
}

class Die{ //Data class for Die
    private int currentFace = 1; //Attribute

    boolean setValue(int newValue) //Set face value for Die
    {
        if (newValue < 1 || newValue > 6) //Check if value is between 1 - 6
            return false;
        this.currentFace = newValue;
        return true;
    }

    int getValue(){ //Return value for current face
        return currentFace;
    }
}

Output:

Explanation:

• Die is a data class used for storing the value of the current face. It has only two methods: setValue() and getValue().
• setValue() is storing a value between the range 1 - 6 and returning false if it's outside the range. getValue() is returning the stored value.
• TwoDice class is the parent class. It has the following methods:
  1. setDie1(): This method is storing value for die1
  2. setDie2(): This method is storing value for die2
  3. getDie1(): This method is fetching value stored in die1
  4. getDie2(): This method is fetching value stored in die2
  5. rollDice(): This method is generating two random numbers between 1 - 6 for both the dice and storing them using setDie1() and setDie2()
  6. getSum(): This method is calling getDie1() and getDie2(). It's adding the numbers of both dice and returning the result
• Main Method: In this method, we are displaying a menu in loop. We are using object of TwoDice to invoke different methods based on the choice. This loop will continue to run as long as the user wants.