Question

下面的代码在运行时效果很好，但是，如果您在“ bands”（带）问题中输入两个单词，您只会得到一个打印回去。

import java.util.Scanner;
public class Main {
  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    System.out.println("What is your name?");
    String name;
    name = scan.next();
    System.out.println("Hello " + name);
    System.out.println("What is your age?");
    int years;
    years = scan.nextInt();
    int ageInMonths;
    ageInMonths = years * 12;
    System.out.print("Your age is ");
    System.out.print(ageInMonths);
    System.out.println(" in months");
    System.out.println("What are your favorite two bands?");
    String bands = scan.next();
    System.out.println("I like >>" + bands + "<<too!");
  }
}

Answer 1

类Scanner中的方法next()将仅返回下一个标记。

如oracle文档中所述：

查找并返回此扫描仪的下一个完整令牌。一种完整令牌的前面和后面都有与定界符模式。等待输入到该方法时可能会阻塞扫描，即使先前对hasNext（）的调用返回true。

默认定界符带有一个空格，因此，如果您的乐队名称包含多个单词，则该单词将无效。

用于读取整行输入用户nextLine()

如果您想同时拥有两个乐队名称，请致电nextLine()两次以分别获取每个输入：

System.out.println("What are your favorite two bands?");
String band1 = scan.nextLine();
String band2 = scan.nextLine();
System.out.println("I like >>" + band1 + " and " + band2 + "<<too!");

在这种情况下，用户必须在每次输入后按“输入”。

编辑：

如Elliott Frisch的评论中所述，其他readXXX方法不会从输入流中删除行尾。看到： stackoverflow.com/q/13102045/2970947

您可以为每个输入使用nextLine（）或在每次读取后删除行尾。带有您的代码的示例：

    Scanner scan = new Scanner(System.in);
    System.out.println("What is your name?");
    String name;
    name = scan.next();
    scan.nextLine();
    System.out.println("Hello " + name);
    System.out.println("What is your age?");
    int years;
    years = scan.nextInt();
    scan.nextLine();
    int ageInMonths;
    ageInMonths = years * 12;
    System.out.print("Your age is ");
    System.out.print(ageInMonths);
    System.out.println(" in months");
    System.out.println("What are your favorite two bands?");
    String bands = scan.nextLine();
    System.out.println("I like >>" + bands + "<<too!");

API参考：

next()

nextLine()

Answer 2

要获取包含多个单词的完整字符串（按enter之前），您应该使用scan.nextLine()而不是scan.next()（scan.next()仅用于读取下一个单词）。

请不要忘记在scan.nextInt（）scan.nextLine() scan.nextLine（）`之后添加额外的and before（请参见Java Scanner class reading strings）：

public static void main(String... args) {
    try (Scanner scan = new Scanner(System.in)) {
        System.out.print("What is your name? ");
        String name = scan.nextLine();
        System.out.println("Hello " + name);

        System.out.print("What is your age? ");
        int years = scan.nextInt();
        int ageInMonths = years * 12;
        System.out.println("Your age is " + ageInMonths + " in months");

        System.out.print("What are your favorite two bands? ");
        scan.nextLine();    // extra one after scan.nextInt() - it retrieves a empty string
        String bands = scan.nextLine();
        System.out.println("I like >>" + bands + "<< too!");
    }
}

演示，控制台输出：

What is your name? John Doe
Hello John Doe
What is your age? 666
Your age is 7992 in months
What are your favorite two bands? one two three
I like >>one two three<< too!

如何解决nextLine错误，以便同时打印两个单词？

2 个答案: