Sum of two dice rolls in java

Question

So I have a dice rolling program that seems to work so far, but the only problem I can't figure out is how to sum the outputs of the rolls. It rolls the dice again while summing the previous roll.

Here is the Die class I started with

public class Die{   //only thing changed was removing implementation of the interface

private int noFaces;

public Die() {
    noFaces = 6;
}

public int getNoFaces() {       //getter
    return noFaces;
}

public Die(int noFaces) {       //setter, sets new value according to passed parameter
    this.noFaces = noFaces;
}

public int roll() {             //generates random number+1 within specified "noFaces" range
    return (int) (Math.random() * noFaces + 1);
}

public void printRoll() {       //goes to above method roll() and prints the returned value
    System.out.println(roll());
}

}

and making one Die into a PairOfDice, which is where I'm having the summation issue

public class PairOfDice {

private Die d1, d2;

public PairOfDice() {       //initializes 2 die objects
    d1 = new Die();
    d2 = new Die();
}

public PairOfDice(int noFaces) {    //sets the dice equally
    d1 = new Die(noFaces);
    d2 = new Die(noFaces);
}   

public PairOfDice(int noFaces1, int noFaces2) { //sets dice separately
    d1 = new Die(noFaces1);
    d2 = new Die(noFaces2);
}

public void printRoll() {   //prints rolls
    System.out.println("Die 1 returned: " + d1.roll());
    System.out.println("Die 2 returned: " + d2.roll());

}

public void printRollSum(){     //print sum of both rolls
    System.out.println("Sum of both dice rolls are: " + (d1.roll() + d2.roll()));
}

}

and where I'm getting the output, RollingDice

public class RollingDice {

public static void main(String[] args) {

    PairOfDice pairOne = new PairOfDice();
    pairOne.printRollSum();
    System.out.println();

    PairOfDice pairTwo = new PairOfDice(10);
    pairTwo.printRoll();
    pairTwo.printRollSum();
    System.out.println();

    PairOfDice pairThree = new PairOfDice(100, 3);
    pairThree.printRoll();
    pairThree.printRollSum();

}

}

All help on either my program or the comments is appreciated, I'm still learning. Thanks!

Answer 1

You are getting the sum of the two dice, but you're rolling the dice each time. printRoll() rolls and displays the values, then printRollSum() rolls them again, giving you different values.

Answer 2

As a solution, you could store the last rolled value in your Die class, (similar to noFaces, but call it lastValue for example), and then change printRollSum() to use getLastValue() instead of roll()

Answer 3

The method roll() will generate a new random number each time it is called so when you call printRoll() and printRollSum() you will receive new numbers each time.

You need to store the results of roll in one of your classes and then provide a method to access those results.

Answer 4

It generates new numbers every time printRoll and printRollSum are called. You should combine the two methods, or at least store the current value of the roll in a die, and access them through printRollSum

Answer 5

Each of your printRoll() and printRollSum() calls is re-rolling the dice. If you're looking to roll the dice, print each individual die's face value, then print the sum of those two face values, you'll need to store the results of the rolls and then perform the sum computation on those results. For example:

public class PairOfDice {

private Die d1, d2;
int lastRollD1;
int lastRollD2;

public PairOfDice() {       //initializes 2 die objects
    d1 = new Die();
    d2 = new Die();
}

public PairOfDice(int noFaces) {    //sets the dice equally
    d1 = new Die(noFaces);
    d2 = new Die(noFaces);
}   

public PairOfDice(int noFaces1, int noFaces2) { //sets dice separately
    d1 = new Die(noFaces1);
    d2 = new Die(noFaces2);
}

public void roll()
{
    lastRollD1 = d1.roll();
    lastRollD2 = d2.roll();
}

public void printRoll() {   //prints rolls
    System.out.println("Die 1 returned: " + lastRollD1);
    System.out.println("Die 2 returned: " + lastRollD1);

}

public void printRollSum(){     //print sum of both rolls
    System.out.println("Sum of both dice rolls are: " + (lastRollD1 + lastRollD1));
}

}

In this version, your RollingDice would then call:

pairOne.roll();
pairOne.printRoll();
pairOne.printRollSum();