Java中的子字符串-长度上限为一个值 [英] Substring in Java - length up to a value

问题描述

我正在尝试创建一个子字符串，该字符串可以让我最多包含6个字母，但是当我发现一个少于6个字母的姓氏时，这里出现的错误似乎是错误的一个没有成功的解决方案:/

I'm trying to make a substring which lets me have up to 6 letters of a surname, however what I have here seems to throw an error when it finds a surname of less than 6 letters, I have been looking for hours for a solution with no sucess :/

id = firstName.substring (0,1).toLowerCase() + secondName.substring (0,6).toLowerCase();
System.out.print ("Here is your ID number: " + id);

它是 .substring(0,6).我需要它最多不超过6个字母(不完全是6个字母).

It's the .substring(0,6). I need it to be up to 6 letters not exactly 6.

错误:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 6
    at java.lang.String.substring(Unknown Source)
    at Test.main(Test.java:27)

推荐答案

使用

secondName.substring (0, Math.min(6, secondName.length()))

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