数组元素中有重复的1,2,2,3；排列组合需要去重的问题

package com.javamvc.learning.former;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

public class TestPage76 {
static StringBuffer stringBuffer = new StringBuffer();
static LinkedList dsLinkedList = new LinkedList<>();
 public static void main(String[] args) {
        String [] array = new String[]{
            "1","2","2","3"
        };
        /*
        将数组转化成列表
         */
        listAll(Arrays.asList(array),"");
        System.out.println(dsLinkedList);
        System.out.println("链表中元素的个数："+dsLinkedList.size());
    }
    public static void listAll(List candidate ,String prefix){

        if(candidate.isEmpty()){
            if(!dsLinkedList.contains(prefix)) {
            	dsLinkedList.add(prefix);
            }
        }
        for(int i =0;i