Java超级简单的对集合排序方法Stream.sorted ()

使用java8 流中的sorted() 方法对元素进行降序排序、升序排序、多字段排序

准备测试数据

 // User[id; age; name; Info[salary]]
        List<User> lists = Lists.newArrayList();
        lists.add(new User(1, 24, "张三", new Info("7000")));
        lists.add(new User(2, 22, "李四", new Info("8500")));
        lists.add(new User(3, 24, "王五", new Info("9000")));

        //  整形集合
        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

升序

        // 按年龄升序
        List<User> userList = lists.stream()
                .sorted(Comparator.comparing(User::getAge))
                .collect(Collectors.toList());

        List<Integer> numberList = numbers.stream()
                .sorted(Comparator.comparing(Integer::intValue))
                .collect(Collectors.toList());

降序

        // 按年龄降序
        List<User> userList = lists.stream()
                .sorted(Comparator.comparing(User::getAge).reversed())
                .collect(Collectors.toList());

        List<Integer> numberList = numbers.stream()
                .sorted(Comparator.comparing(Integer::intValue).reversed())
                .collect(Collectors.toList());

多字段排序

        // 关键字thenComparing
        //  1.先以年龄升序  2.当年龄相同时，在以薪资升序
        List<User> userList = lists.stream()
                .sorted(Comparator.comparing(User::getAge).thenComparing(User::getSalary))
                .collect(Collectors.toList());

多字段即升序又降序排序

        // 关键 thenComparing、Comparator.reverseOrder()
        //  1.先以年龄升序  2.当年龄相同时，在以薪资降序
        List<User> userList = lists.stream()
                .sorted(Comparator.comparing(User::getAge).thenComparing(User::getSalary,Comparator.reverseOrder()))
                .collect(Collectors.toList());