Java正則表達式校驗十三位純數字字符串

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class EAAN13 {

    public static void main(String[] args) {
       isEAN13();
    }

    private  static  void isEAN13(){
        int cho;
        Scanner scanner = new Scanner(System.in);
        Scanner scanner1 = new Scanner(System.in);
        String demo= "";
        while (true){
            System.out.println("*****************");
            System.out.println("*****1、校驗EAN13******");
            System.out.println("*****2、退出程序*******");
            System.out.println("*****************");
            System.out.print("請選擇：");
            cho = scanner.nextInt();
            switch (cho) {
                case 1:
                    System.out.println("請輸入你要轉換的EAN13：");
                    demo = scanner1.next();
                    int end = isNumeric(demo);
                    if (end == 1){
                        System.out.println("校驗碼合格！");
                    }else{
                        System.out.println("您的輸入不符合EAN13規定的要求請重新選擇:");
                        isEAN13();
                    }
                    break;
                case 2:
                   System.exit(0);
                   break;
                default:
                    System.out.println("輸入錯誤！");
            }
        }
    }
    
    private static int isNumeric(String str)
        //正則表達式校驗13位數字
    {
        Pattern pattern = Pattern.compile("\\d{13}");
        //System.out.println(pattern.pattern());
        Matcher isNum = pattern.matcher(str);
        if( !isNum.matches() )
        {
            return 0;
        }else{
            return 1;
        }
    }

}