(Original) Determine whether there are duplicate elements in the List list

Encountered a practical problem today

How to judge whether there are duplicate elements in a List

I thought it was impossible to compare them one by one

So I checked and found that I can use the characteristics of HashSet to do it

Because duplicate elements are not allowed in the Set collection

So get the following processing

    /**
     * 列表中是否包含重复元素
     *
     * @param list
     * @return
     */
    public static boolean isRepeatList(List list) {
        if (list == null || list.isEmpty()) {
            return false;
        }
        Set set = new HashSet<>(list);
        if (set.size() == list.size()) {
            return false;
        } else {
            return true;
        }
    }