Question

当前停留在一项要求我打印用户名的作业上，例如：Last，First Initial。（Bob，BillyH。）如果在输入时在名字和中间名之间添加太多空格，则会获得索引超出范围的异常。（字符串超出范围0）除非我的名字和中间名之间有多个空格，否则程序将完全正常运行。

我只能在该程序中使用trim，indexOf，substring和charAt方法。

import java.util.Scanner;

public class Name {

public static void main(String[] args) {

    Scanner s = new Scanner(System.in);

    System.out.println("Enter your name in this format: <spaces>First name<spaces>Middle name<spaces>Last name<spaces>");

    String name = s.nextLine();

    name = name.trim();

    String first, middle, last;

    int firstSpace = name.indexOf(' ');

    first = name.substring(0, firstSpace);

    int secondSpace = name.indexOf(" ", (firstSpace + 1));

    middle = name.substring((firstSpace + 1), secondSpace);

    middle.trim();

    last = name.substring(secondSpace+1);

    char middleInitial = middle.charAt(0);
    String initial = "";
    initial = initial + middleInitial;

    for(int i = 1; i < middle.length(); i++) {
        char currentLetter = middle.charAt(i);
        char lastLetter = middle.charAt(i - 1);

        if(lastLetter == ' ') {
            initial = initial + "." + currentLetter;
        }
    }

    System.out.println(last + "," + first + ' ' + initial + ".");

}

}

Answer 1

输入错误的原因

   amid     skum    asdf

以上输入：

int firstSpace = name.indexOf(' '); //firstSpace = 0
int secondSpace = name.indexOf(" ", (firstSpace + 1));//secondSpace = 1
 middle = name.substring((firstSpace + 1), secondSpace); // as the two or more continues space inputted, this will select empty string as firstSpace + 1 == secondSpace and later causing the exception

执行name = name.replaceAll(" +", " ");来替换所有两个或更多的空格。正如karthik在评论中建议的那样，执行作业middle = middle.trim();。

编辑： 由于无法使用replaceAll，因此仅使用trim方法即可修改代码。请仔细阅读以下片段：

 String middleNameLastName = name.substring(firstSpace+1).trim();
 last = middleNameLastName.substring(index+1).trim();

这些将删除尾随空格。

import java.util.Scanner;

public class Post1 {

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

        System.out.println("Enter your name in this format: <spaces>First name<spaces>Middle name<spaces>Last name<spaces>");

        String name = s.nextLine();

        name = name.trim();
        String first, middle, last;
        int firstSpace = name.indexOf(' ');
        first = name.substring(0, firstSpace);
        String middleNameLastName = name.substring(firstSpace+1).trim();
        int index = middleNameLastName.indexOf(" ");
        middle = middleNameLastName.substring(0, index);
        last = middleNameLastName.substring(index+1).trim();

        System.out.println(last + "," + first + ' ' + middle.charAt(0) + ".");
        s.close();
    }

}

当我有太多空白时，CharAt（0）超出范围异常

1 个答案: