Java - 扫描器导致循环到 运行 两次

Question

我对 Java 和一般编程还很陌生。我正在尝试询问名人的名字并将它们放在一个数组中。当我尝试使用扫描仪读取用户的输入时，它设法存储了名称，但在循环条件之前运行了 System.out.println("Name is too short, try again"); 行。

以下是我的代码中的相关部分：

public static final Scanner scan = new Scanner(System.in);

public static void main(String[] args) {

    String celeb[];
    int number;
    System.out.println("Welcome to Celebrity Guesser!");
    System.out.println("How many celebrities do you want to name?");
    number = scan.nextInt();
    celeb = new String[number];

    for(int i = 0; i < number; i++) {   //asks for user input
        celeb[i] = celebInput(i + 1);
    }
    for(int i = 0; i < number; i++) {   //asks questions to user
        String tempCeleb = celeb[i];
        celebOutput(tempCeleb, i + 1);
    }
}

//Reads names of celebrities from the user
static String celebInput(int n) {
    System.out.println("\nType in celebrity #" + n);
    String c = scan.nextLine();
    while(c.length() < 6) {
        System.out.println("Name is too short, try again");
        c = scan.nextLine();
    }
    return c;
}

这是输出：

Welcome to Celebrity Guesser!
How many celebrities do you want to name?
2

Type in celebrity #1
Name is too short, try again
Miley Cyrus

Type in celebrity #2
Katy Perry

为什么这个问题只发生在 "celebrity #1" 而不是 "celebrity #2"？谢谢。

Answer 1

scan.nextInt 只会从输入流中删除“2”。你回车时输入的“\n”（换行符）还在输入流中；因此，第一个 nextLine 调用将 return 一个空行。

澄清一下：

    // assuming we enter "2\ntest\n" at the command line
    Scanner s = new Scanner(System.in); // s now contains "2\ntest\n"
    System.out.println(s.nextInt()); // s now contains "\ntest"
    System.out.println(s.nextLine()); // s now contains "test"
    System.out.println(s.nextLine()); // s is empty

输出：

"2"
""
"test"

解决办法是在nextInt之后调用nextLine清除空行。

Answer 2

尝试 number = Integer.parseInt(scan.nextLine()); 而不是 number = scan.nextInt();

希望有用。让我知道。