stream-常用数组操作

对listResult进行排序,根据伴随度进行降序,根据集合中对象User中的伴随度进行倒序排列…reversed(),默认正序,reversed反转后即倒序;

1
2
3

List<User> collect = listResult.stream()
       .sorted(Comparator.comparing(User::getUserId()).reversed())
       .collect(Collectors.toList());

过滤出User中UserId大于1的结果,firstA中存放的都是的大于1的

1
2
3

List<User> firstA = listResult.stream()
               .filter(User -> user.getUserId() >= 1)
               .collect(Collectors.toList());

1
2
3

List<User> result = listResult.stream()
      .sorted(Comparator.comparing(User::getUserId()))
      .collect(Collectors.toList());

1	List<Integer> collect = listResult.stream().map(e->e.getUserId()).collect(Collectors.toList());

1 2	Map<Integer, User> map = listResult.stream().collect(Collectors.toMap(User::getUserId, User -> User));