运行时未显示Java字符串[重复]

Posted 2023-02-25

【中文标题】运行时未显示Java字符串[重复]

【英文标题】：Java string not showing when run [duplicate]

【发布时间】：2014-11-18 21:55:36

【问题描述】：

我似乎无法弄清楚为什么当我运行它时字符串学院没有显示。我编译时没有错误。我究竟做错了什么？其他一切都在工作。这可能很容易解决，但我是新手，刚开始学习 Java。

import java.util.Scanner;
public class story_a_holloway
public static void main(String[] args)
   String name;
   String city;
   int age;
   String college;
   String profession;
   String animal;
   String petname;

   Scanner keyboard = new Scanner(System.in);

   // Get name
   System.out.print("What is your name? ");
   name = keyboard.nextLine();

   // Get city
   System.out.print("What city do you live in? ");
   city = keyboard.nextLine();

   // Get age
   System.out.print("What is your age? ");
   age = keyboard.nextInt();

   // Get college
   System.out.print("What college do you attend? ");
   college = keyboard.nextLine();

   keyboard.nextLine();
   // Get profession
   System.out.print("What is your profession? ");
   profession = keyboard.nextLine();

   // Get animal
   System.out.print("What is your favorite animal? ");
   animal = keyboard.nextLine();

   // Get pet name
   System.out.print("What would you name your pet? ");
   petname = keyboard.nextLine();

   System.out.println("There once was a person named " + name + " who lived in " + city + ". At the age of " + age + ", " + name + " went to college at " + college + ". " + name + " graduated and went to work as a " + profession + ". Then " + name + " adopted a(n) " + animal + " named " + petname + ". They both lived happily ever after!");

【问题讨论】：

你能提供一个示例输出吗？

为什么在college = keyboard.nextLine() 之后有额外的keyboard.nextLine() 调用？

【参考方案1】：

在age = keyboard.nextInt(); 之后调用keyboard.nextLine()。

当前int 值被读取为年龄，college = keyboard.nextLine(); 读取包含您的int 的行的其余部分，该行是空的。所以正确的形式应该是：

// Get age
System.out.print("What is your age? ");
age = keyboard.nextInt();
keyboard.nextLine();

// Get college
System.out.print("What college do you attend? ");
college = keyboard.nextLine();

避免额外调用nextLine() 的其他可能解决方案是将整行读取为字符串，然后将该字符串解析为整数，例如：

age = Integer.parseInt(keyboard.nextLine());

【讨论】：

您还可以使用两个Scanner 对象：一个用于字符串输入，一个用于数字输入。然而，这太过分了。这里的重要问题是要知道，为了重用Scanner 对象，它必须被完全消耗掉。如前所述，一些nextXXX()methods 会留下换行符。使用nextLine() 方法是清空输入流的一种解决方法，以便下次尝试获取下一个字符串时，它会按照预期的方式工作。

【参考方案2】：

在这行后面加上keyboard.nextLine()：

int age=keyboard.nextInt();

这是在Scanner 类的nextInt() 方法之后使用nextLine() 方法时通常会发生的常见问题。

实际发生的情况是，当用户在int age = keyboard.nextInt(); 处输入一个整数时，扫描程序将只获取数字并留下换行符\n。所以你需要通过调用keyboard.nextLine(); 来做一个技巧，只是为了丢弃那个换行符，然后你可以毫无问题地调用String college = keyboard.nextLine();。

这取自Reading Strings next() and nextLine() Java

【讨论】：

如果您知道该问题与另一个问题重复，请不要重新发布其答案，而是将其标记为重复。

Pshemo 我实际上也将它标记为重复，奇怪的是它没有显示在问题下方的评论字段中。它之前确实说过 mrsimplemind 将其标记为重复和 url。无论如何感谢您的澄清。

【参考方案3】：

你的代码的问题是在 nextInt() 之后使用 nextLine() 并且你有一个额外的 nextLine()

// Get age
System.out.print("What is your age? ");
age = keyboard.nextInt();

// Get college
System.out.print("What college do you attend? ");
college = keyboard.nextLine();

keyboard.nextLine(); --> this line
// Get profession
System.out.print("What is your profession? ");
profession = keyboard.nextLine();

你应该做的是：

// Get age
System.out.print("What is your age? ");
age = keyboard.nextInt();
keyboard.nextLine(); -->add this line

// Get college
System.out.print("What college do you attend? ");
college = keyboard.nextLine();

// keyboard.nextLine(); --> remove this line
// Get profession
System.out.print("What is your profession? ");
profession = keyboard.nextLine();

一个更好的方法是：（阅读Integer.pasrseInt(String)）

// Get age
System.out.print("What is your age? ");
age = Integer.parseInt(keyboard.nextLine());

【参考方案4】：

    import java.util.Scanner;
    public class story_a_holloway
    public static void main(String[] args)
        String name;
        String city;
        int age;
        String profession;
        String animal;
        String petname;
        String college;
        Scanner keyboard = new Scanner(System.in);

        // Get name
        System.out.print("What is your name? ");
        name = keyboard.nextLine();

        // Get city
        System.out.print("What city do you live in? ");
        city = keyboard.nextLine();

        // Get age
        System.out.print("What is your age? ");
        age = Integer.parseInt(keyboard.nextLine());

        // Get college
        System.out.print("What college do you attend? ");
        college = keyboard.nextLine();

        // Get profession
        System.out.print("What is your profession? ");
        profession = keyboard.nextLine();

        // Get animal
        System.out.print("What is your favorite animal? ");
        animal = keyboard.nextLine();

        // Get pet name
        System.out.print("What would you name your pet? ");
        petname = keyboard.nextLine();
        System.out.println(college);
        System.out.println("There once was a person named " + name + " who lived in " + city + ".    At the age of " + age + ", " + name + " went to college at " + college + ". " + name + " graduated and went to work as a " + profession + ". Then " + name + " adopted a(n) " + animal + " named " + petname + ". They both lived happily ever after!");