unique year

package main;

import java.util.Scanner;

public class Main
{
  public static void main(String[] args)
  {
    Scanner input = new Scanner(System.in);
    Boolean checker = true;
	String regex = "^(?:([0-9])(?!.*\1))*$";
	Pattern pattern = Pattern.compile(regex,Pattern.CASE_INSENSITIVE);
    
    System.out.println("Enter the Year:");
    String number = input.next();
	
	Matcher matcher;
	while(!checker) {
		matcher = pattern.matcher(number);
		if(matcher.find())
			checker = true;
		else
			number++;
	}
	System.out.println(number);
	
  } 
 }