将计数器设置为 0，然后使用方法添加计数器使其保持为 0

Question

我有一个猜测程序，我正在尝试添加一个计数器。在粗体部分我有一个柜台。当您猜错时，它会在计数器上加 1。但是当它打印它时，无论如何它只是打印为0。

                    public static void firstGame(String Answer, String userGuess, int counter)
                {
                    userInput = new Scanner(System.in);

                    boolean playgame = true;

                    while(playgame == true)
                    {
                    Answer = "Sam";

                    lnPrint(" ");
                    lnPrint("Take a guess at my name! It starts with an S...");
                    sPrint(":");
                    userGuess = userInput.next();

                    if(userGuess.equalsIgnoreCase(Answer))
                        {
                            lnPrint("You got it! Its " + Answer);
                            lnPrint(" ");
                            break;
                        }

                    else if(userGuess != Answer)
                        {
                            lnPrint("Good guess, keep trying!");
                            counter++;
                        }

                    }
                }

这是我与柜台的游戏方法。

public static void main(String[] args)
    {
        Scanner userInput = new Scanner(System.in);

        int Start, counter = 0;
        String Answer, userGuess, middleAnswer, middleUserGuess;
        Answer = null;
        userGuess = null;
        middleAnswer = null;
        middleUserGuess = null;
        Start = 0;

            while(Start !=2)
            {

            lnPrint("(1) Start Game");
            lnPrint("(2) Exit");
            sPrint(":");
            Start = userInput.nextInt();

                if(Start == 1)
                    {
                        firstGame(userGuess, Answer, counter);
                        lnPrint("Now, how about my middle name?");
                        nlnPrint(counter);
                        middleGame(middleAnswer, middleUserGuess);

                    }

这是打印它的代码

Answer 1

这看起来像是一个常见的按值/引用传递问题。当使用counter 作为firstGame 的参数时，在firstGame 方法中使用的是counter 的值，而不是传递引用到counter 变量；您可以在此处阅读相关内容，例如：http://www.javacoffeebreak.com/faq/faq0066.html

有一些方法可以通过引用方法来传递整数（参见Java : Best way to pass int by reference），但在这种情况下，我认为您应该简单地将counter 声明为全局变量。

Answer 2

你之前有没有初始化过“计数器”？ 这是一个有效的例子：

$.Guess = function() {
    var parent = this;
    var counter = 0;

    this.guess = function(val) {
        if ( val != 5 ) {
            parent.guessedWrong();
        }
    }
    this.guessedWrong = function() {
        counter++;
    }
    this.guessed = function() {
        return counter;
    }
    this.resetCounter = function() {
        counter = 0;
    }
}


var game = new $.Guess();
game.guess(1);
game.guess(2);
alert( game.guessed() );

game.guess(3);
game.guess(4);
game.guess(5);
// Alerts 4, because there is 5 guesses and one of them (the one with value 5) is correct
alert( game.guessed() );
// Reset counter to 0
game.resetCounter();

game.guess(6);
game.guess(7);
game.guess(8);
alert( game.guessed() );

..上面的代码可以在这里测试：http://jsfiddle.net/jcpjr9dc/