'Simple Coin Toss using random class in Java. The do while loop doesn't seem to generate random results

I'm having issues generating the random number each time I run through the do-while loop in main. When I remove the do - while statement the if statement works fine and seems to generate a random result each time but when it is repeated in the loop it seems to just repeat the initial result.

Here is my code:

import java.util.Random;

public class CoinToss {
    private enum Coin {Heads, Tails};

    Random randomNum = new Random();
    private int result = randomNum.nextInt(2);
    private int heads = 0;
    private int tails = 1;
    Coin coinFlip;

    public void flip() {
        if (result == 0) {
            coinFlip = Coin.Heads;
            System.out.println("You flipped Heads!");
        } else {
            coinFlip = Coin.Tails;
            System.out.println("You flipped Tails!");
        }
    }
}

And my method main where I seem to be having issues:

import java.util.Scanner;

public class TossGame {
    public static void main(String[] args) {
        CoinToss test = new CoinToss();
        int choice;

        System.out.println("Welcome to the coin toss game!");
        do {
            System.out.print("Enter 1 to toss coin or enter 0 to quit: ");
            Scanner input = new Scanner(System.in);
            choice = input.nextInt();

            if (choice == 1) {
                test.flip();
            } else if (choice > 1) {
                System.out.println("Invalid entry - please enter 1 or 0: ");
                choice = input.nextInt();
            }
        } while (choice != 0);
    }
}
javarandom


Solution 1:[1]

You only "flipped" once, when you initialized result:

private int result = randomNum.nextInt(2);

When you call flip, get another result:

public void flip(){
    result = randomNum.nextInt(2);  // Add this line
    if(result == 0){

Solution 2:[2]

You need to randomize a flip each time you call flip(), not when CoinToss is constructed:

public class CoinToss {

private enum Coin{Heads, Tails};

Random randomNum = new Random();
private int result;
private int heads = 0;
private int tails = 1;
Coin coinFlip;

public void flip(){
    result = randomNum.nextInt(2)
    if(result == 0){
        coinFlip = Coin.Heads;
        System.out.println("You flipped Heads!");
    }else{
        coinFlip = Coin.Tails;
        System.out.println("You flipped Tails!");
    }
}

Solution 3:[3]

if (Math.random() < .5){
    System.out.println("Heads");
}else{
    System.out.println("Tails");
}

This could be the simplest solution for coin toss.

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 rgettman
Solution 2 bstar55
Solution 3 Jency

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