Question

程序代码：

public static void main(String[] args) throws IOException {

    System.out.print("Welcome to my guessing game! "
            + "Would you like to play (Y/N)? ");
    yesOrNoAnswer = (char)System.in.read();

    if(yesOrNoAnswer == 'Y') {
        System.out.print("\n\nGuess the number (between 1 and 10): ");
        while(AnswerIsCorrect == false) {
            guess = System.in.read();

            if(guess == correctAnswer) {
                AnswerIsCorrect = true;
            }
            else {
                System.out.print("\nYou guessed wrong! Please try again: ");
            }
        }
        System.out.print("You guessed correct! Congratulations!"
                + "\n\nPress any key to exit the program . . .");
        System.in.read();
    }
}

预期产出：

Welcome to my guessing game! Would you like to play (Y/N)? Y


Guess the number (between 1 and 10):

实际输出：

Welcome to my guessing game! Would you like to play (Y/N)? Y


Guess the number (between 1 and 10): 
You guessed wrong! Please try again:

当我在第一个问题输入'Y'时（你想播放），它继续输出，“猜数字1到10之间：”这是一个很好的输出。但是，在我输入数字之前，它会立即输出，“你猜错了！请再试一次：”

如何修复此代码以实现预期的输出？

Answer 1

问题在于您使用System.in.read()。

System.in.read()将逐个读取字符并将其作为int返回。如果我输入1，则System.in.read()将返回49，因为该字符1被编码为。

为什么它会立即打印您的猜测错误而不让您输入任何内容的原因是System.in.read()也会读取新行字符。如果有任何未读的内容，它会读取该内容，而不是要求新的输入。在您输入的Y后面有一个换行符，因此它会读取该换行符。

您应该使用Scanner：

    Scanner scanner = new Scanner(System.in); // create a new scanner
    System.out.print("Welcome to my guessing game! "
        + "Would you like to play (Y/N)? ");
yesOrNoAnswer = scanner.nextLine().charAt(0); // reading the first character from the next line

if(yesOrNoAnswer == 'Y') {
    System.out.print("\n\nGuess the number (between 1 and 10): ");
    while(AnswerIsCorrect == false) {
        guess = Integer.parseInt(scanner.nextLine()); // get an int from the next line

        if(guess == correctAnswer) {
            AnswerIsCorrect = true;
        }
        else {
            System.out.print("\nYou guessed wrong! Please try again: ");
        }
    }
    System.out.print("You guessed correct! Congratulations!"
            + "\n\nPress any key to exit the program . . .");
    scanner.nextLine();
}

Scanner.nextLine()将返回用户输入的字符串输入，并忽略换行符。

while循环中的代码行在错误的时间执行

1 个答案: