java - 我正在尝试检查电子邮件是否具有三个字母扩展名，例如“ .com”或“ .net”，并且此方法不起作用(I am trying to check if an email has a three letter extension such as “.com” or “.net” or not and this is not working)

Question

this is not working and I cannot figure out why

(这是行不通的，我不知道为什么)

do {
    System.out.println("enter your work email");
    workEmail = scnr.nextLine();
    if (workEmail.substring(workEmail.length() - 4) != ".") {
        System.out.println("Please enter a valid email. example: [email protected]");
    }

} while (workEmail.substring(workEmail.length() - 4) != ".");

  ask by jackspurrrr translate from so

Answer 1

Your solution has two main issues:

(您的解决方案有两个主要问题：)

1. You should never compare Strings using == or != .

   (您永远不要使用==或!=比较字符串。)

   Use .equals() or even better StringUtils.equals() .

   (使用.equals()或更好的StringUtils.equals() 。)

2. You're using subString() , when you want to use charAt() .

   (当您要使用charAt()时，您正在使用subString() charAt() 。)

   While chatAr would work, the solution from @YCF_L s comment using .endWith() is way superior.

   (虽然chatAr可以工作，但使用.endWith() @YCF_L注释中的解决方案更为出色。)