java 获取两个list不同元素

/**
	 * 获取两个List的不同元素
	 * @param list1
	 * @param list2
	 * @return
	 */
	public static List<String> getDiffrent(List<String> list1, List<String> list2) {
		long st = System.nanoTime();
		List<String> diff = new ArrayList<String>();
		List<String> maxList = list1;
		List<String> minList = list2;
		if(list2.size()>list1.size())
		{
			maxList = list2;
			minList = list1;
		}
		Map<String,Integer> map = new HashMap<String,Integer>(maxList.size());
		for (String string : maxList) {
			map.put(string, 1);
		}
		for (String string : minList) {
			if(map.get(string)!=null)
			{
				map.put(string, 2);
				continue;
			}
			diff.add(string);
		}
		for(Map.Entry<String, Integer> entry:map.entrySet())
		{
			if(entry.getValue()==1)
			{
				diff.add(entry.getKey());
			}
		}
		System.out.println("Diffrent total times "+(System.nanoTime()-st));
		return diff;

	}