Java中List去重的多种方法

//Stream 去重：list.stream().distinct()
public static List removeDuplicate(List list) {
    HashSet hashSet = new HashSet(list);
    list.clear();
    list.addAll(hashSet);
    return list;
}


//通过 HashSet 剔除重复元素
public static List removeDuplicate(List list) {
    List newList = (List) list.stream().distinct().collect(Collectors.toList());
    return newList;
}


//通过HashSet剔除重复元素
public static List removeDuplicate(List list) {
    Set set = new HashSet();
    List newList = new ArrayList();
    for (Iterator iter = list.iterator(); iter.hasNext(); ) {
        Object next = iter.next();
        if (set.add(next)) {
            newList.add(next);
        }
    }
    list.clear();
    list.addAll(newList);
    return list;
}
//遍历 list，用 tempList.contain()
public static List removeDuplicate(List list) {
    List tempList = new ArrayList();
    for (int i = 0; i < list.size(); i++) {
        if (!tempList.contains(list.get(i))) {
            tempList.add(list.get(i));
        }
    }
    return tempList;
}

//循环 list 中的所有元素然后删除重复
public static List removeDuplicate(List list) {
    for (int i = 0; i < list.size(); i++) {
        for (int j = list.size() - 1; j > i; j--) {
           if (list.get(i).equals(list.get(j))) {
                list.remove(list.get(i));
            }
        }
    }
    return list;
}