List对象集合的简单去重

list = list.stream().distinct().collect(Collectors.toList());

List集合的根据属性（name）去重

list = list.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(()->new TreeSet<>(Comparator.comparing(Student::getName))), ArrayList::new));

List对象集合的简单过滤（过滤为 null 的对象）

list = list.stream().filter(item -> item.getName() != null).collect(Collectors.toList());

List对象集合中获取其中某一属性（weight）的List集合

List<Double> collect = apples.stream().map(Apple::getWeight).collect(Collectors.toList());

List对象集合转换为逗号连接的字符串

String str = list.stream().map(String::valueOf).collect(Collectors.joining(","));

List对象集合中根据对象（Apple）的某一属性（color）进行分组

Map<String, List<Apple>> applesByColor = apples.stream().collect(Collectors.groupingBy(Apple :: getColor));

List对象集合中求和、最大、最小、平均的统计（mapToDouble()）

//和
double sum = apples.stream().mapToDouble(Apple::getWeight).sum(); 
//最大
OptionalDouble max = apples.stream().mapToDouble(Apple::getWeight).max(); 
//最小
OptionalDouble min = apples.stream().mapToDouble(Apple::getWeight).min(); 
//平均值
OptionalDouble average = apples.stream().mapToDouble(Apple::getWeight).average(); 

List对象集合的分页（skip()+limit()）

List<User> resultList = list.stream().skip(pageSize * (currentPage - 1)).limit(pageSize).collect(Collectors.toList());