如何用java解决这个问题？

Question

用户输入的机票和车票应与B，E，F（不区分大小写前。BEF也可）来启动和3位..

，如果他们进入票的正确格式比书票 否则无效票后错误。例如

。

的Java票务 输入票>> B100 成本$ 200.0 的Java票务 输入票>> A609 无效票，车票必须在B，F或E java的票务 输入票>> 1234567890987 无效的开始票，错误的长度，长度必须为4和10包容

之间

代码是

import java.util.*; 
public class Ticket 
{ 

    public static void main(String[] ar)throws IOException 
    { 
     Scanner keb = new Scanner(System.in); 
     System.out.println("Enter ticket := "); 
     String ticket=keb.nextLine(); 



     if(checkTickt) 
     { 
      System.out.println("valid ticket"); 
     } 
     else{ 
      System.out.println("Invalid ticket, ticket must start with B, F or E"); 
     } 
    } 
} 

Answer 1

你所想要实现这个比较：

Pattern pattern = Pattern.compile("(?i)[bef]\\d{3}"); 
if (pattern.matcher(ticket).matches()) { 
    System.out.println("valid ticket"); 
} else { 
    System.out.println("Invalid ticket, ticket must start with B, F or E"); 
} 

Answer 2

尝试使用正则表达式：

import java.io.IOException; 
import java.util.Scanner; 

public class Ticket { 

    public static void main(String[] ar) throws IOException { 
     Scanner keb = new Scanner(System.in); 
     System.out.println("Enter ticket:"); 
     String ticket = keb.nextLine(); 
     String pattern = "[BbFfEe][0-9]{3}"; 


     if (ticket.matches(pattern)) { 
      System.out.println("Ticket is VALID."); 
     } else { 
      System.out.println("Ticket is INVALID, it must starts with B, b, F, f, E, e characters following by 3 digits."); 
     } 
    } 
} 

了解更多：Lesson: Regular Expressions