Java stream 速查手册

分组

List<MjConfig> mjConfigs = new ArrayList<>()；
// 根据Type类型分组
Map<String, List<MjConfig>> map = mjConfigs.stream().collect(Collectors.groupingBy(MjConfig::getType));

提取元素属性

List<User> list = new ArrayList<>();
List<String> names = list.stream().map(User::getName).distinct().collect(Collectors.toList());