java使用List.contains进行比较

import java.util.*;

public class Main{
    public static void main(String [] args){
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        LinkedList<Integer> list = new LinkedList<>();
        while(num > 0){
            int n = num % 10;
            num = num / 10;
            if(!list.contains(n)){
                list.add(n);
                System.out.print(n);
            }
        }
    }
}