Rework blackjack game

问题:

I'm trying to create a blackjack game, where the player starts off with 2 cards, and then asked if he/she would like to have another card (user input: yes or no), if yes, another card is added to the total. if no, the game just terminates.

Here is a sample output I'm trying to get:

And this is what I have so far (It's probably wrong in terms of the placement):

import java.util.Scanner;

public class BlackJackGame {
    public static void main(String[] args) {

        int randomnum1 = (int) (1 + Math.random() * 10);
        int randomnum2 = (int) (1 + Math.random() * 10);
        int randomnum3 = (int) (1 + Math.random() * 10);
        int total;
        char anotherCard = 'y';

        Scanner input = new Scanner(System.in);

        System.out.println("First cards: " + randomnum1 + ", " + randomnum2);

        total = randomnum1 + randomnum2;

        System.out.println("Total: " + total);

        while (anotherCard != 'n')
        {   
            System.out.print("Card: " + randomnum3);

            System.out.print("Do you want another card? (y/n): ");
            anotherCard = input.next().charAt(0);           
        }   
    }
}

Tips and reworking the source code will be highly appreciated.

回答1:

As Far as card games go, there are 52 cards in a deck, and I'm assuming there's one deck.

If you want it to be a fair game, then you have to keep that in mind.

But if you just want output to look correct, you just have to avoid getting more than 4 aces, 2's, 3's, and 4's.

One way to achieve this would be to make an int array of size 52 with 4 of each card. I suppose Ace would be 1 and 10,J,Q,K would be 10, so there would be 16 10's.

Get a random number between 0 and 51 to get the index of the array you want to use. Once you use that index, set the value of that array = -1, and always check for -1 before using that index, and if it is -1, get another random value.

int [] deck = size 52 array with 4 of each card.
int random = get random number between 0 and 51.

while(deck[random] == -1){
   random = get random number between 0 and 51.
}
int card1 = deck[random]
deck[random] = -1;

something like that.. I just did that quickly, hopefully you get the idea.

回答2:

Here are the tips you requested:

• You need to introduce a variable to keep track of your sum. For example, you could initialize it with: int sum = randomnum1 + randomnum2; and keep adding the next card to it inside the loop: sum += randomnum3;
• You need to generate randomnum3 inside the while loop. This way, you will get a different card every time. Basically, you have to call the random function every time you generate a card, not just once. Otherwise the value of randomnum3 will be unchanged and you will get the same card over and over.
• To exit when you get to 21, you would have to use if and possibly break within the loop, once you have added the current card to the sum: if(sum > 21) { break; }
• Alternatively, you can set the value of anotherCard to 'n' instead of using a break
• You should keep track of which cards the user has already gotten if you want to simulate an actual deck. This is not technically necessary for the program you appear to be writing though.

回答3:

Here are a few simple improvements for you to look over. I'll leave it like this as part of the joy of learning to program is in the discovery. As a next step I'd suggest generating a dealers hand and then seeing if the player can beat it. Good luck!

public static void main(String[] args) {
    int card1 = (int) (1 + Math.random() * 10);
    int card2 = (int) (1 + Math.random() * 10);
    int total = card1 + card2;

    System.out.println(String.format("First cards: %d & %d.  Total %d", card1, card2, total));
    System.out.println();

    Scanner input = new Scanner(System.in);

    System.out.print("Do you want another card? (y/n): ");
    char anotherCard = input.next().charAt(0);
    while (anotherCard != 'n' && total < 21) {
        int nextcard = (int) (1 + Math.random() * 10);
        total += nextcard;
        System.out.println(String.format("You drew a %d.  Your total is now %d", nextcard, total));

        if (total > 21) {
            System.out.println("You busted!");
        } else {
            System.out.print("Do you want another card? (y/n): ");
            anotherCard = input.next().charAt(0);
        }
    }
}