java如何接受enter作为扫描仪的有效输入。nextLine（）？

Question

我只想让扫描器将新行读取为空字符串，然后在用户按enter键时继续下一个过程。所以有效输入必须是y，n，enter。你知道怎么做吗

这是我的代码：

String gender = "", employed = "";
Scanner in = new Scanner(System.in);
System.out.print("Gender M/F, press enter to skip... ");
while(!in.hasNext("[mfMF]$")){
    System.out.print("Invalid, please choose m/f only... ");
    in.nextLine();
}
if(in.hasNextLine()){
    gender = in.nextLine();
}
System.out.print("Employed? y/n, press enter to skip... ");
    while(!in.hasNext("[ynYN]$|")){
        System.out.print("Invalid, please choose y/n only... ");
        in.nextLine();
    }
if(in.hasNextLine()){
    employed = in.nextLine();
}
System.out.println(gender + " : " + employed);

Answer 1

因此，要检查用户是否按了enter键，必须使用isEmpty（）方法。方法如下所示：

String enter = in.nextLine();
if (enter.isEmpty()) {
   // do what is needed
}

Answer 2

试试这个：

import java.util.*;

class Scanner1
{
   public static void main(String args[])
   {
     Scanner sc=new Scanner(System.in);
     String s;
     do
     {
        s=sc.nextLine();
           if(!(s.equalsIgnoreCase("y")||s.equalsIgnoreCase("n")||s.equalsIgnoreCase("")))
        {
            System.out.println("Please Enter valid input");
        }

    }while(!(s.equalsIgnoreCase("y")||s.equalsIgnoreCase("n")||s.equalsIgnoreCase("")));

    }
}