如何在不使用阵列的情况下检查车牌是否有效？

Question

I was going to submit this code below but the TA said that I cannot use arrays. I'm not really sure how to do this without arrays. He said it was much simpler than what I did.

package b4;
import java.util.Scanner;
public class b2 {
    public static boolean isAlpha(String name) {
        char[] chars = name.toCharArray();
        for (char c : chars) {
           if (!Character.isLetter(c)) {
               return false;
           }
        }
        return true;
     }

     public static void main(String[] args)
     {
         Scanner scn=new Scanner(System.in);
         System.out.print("Enter a valid plate number: ");
         String plate=scn.next();

         if (plate.length()==5) {
             if (plate.contains("-")) {
                 String[] sp=plate.split("-");

                 if (isAlpha(sp[0])&&sp[0].length()==2) {
                     try {
                         Integer.parseInt(sp[1]);
                         System.out.println(plate+" is a a valid plate number.");
                     } catch(Exception e) {
                         System.out.println(plate+" is a an invalid plate number.");
                     }
                 } else {
                     System.out.println(plate+" is a an invalid plate number.");
                 }
             } else {
                 System.out.println(plate+" is a an invalid plate number.");
             }

         } else {
             System.out.println(plate+" is a an invalid plate number.");
         }
     }
}

Here was the question we were given originally which didn't mention we couldn't use arrays.

Answer 1

Can you use RegEx? If you can, it's pretty simple.

Your RegEx code could look something like this:

\b[A-Z][A-Z]-[0-9][0-9]\b

You can then use the matches() function to check if the input works.