Stream List 的排序

https://blog.csdn.net/yiyihuazi/article/details/123681478

 

 

1、list的正序

 

List<Integer> list = new ArrayList<>();

list.add(50);

list.add(45);

list.add(25);

list.add(98);

list.add(32);

List<Integer> collect = list.stream().sorted().collect(Collectors.toList());

System.out.println("list<Integer>元素正序：" + collect);

 

打印结果：

list<Integer>元素正序：[25, 32, 45, 50, 98]

 

2、list的倒序

 

List<Integer> list = new ArrayList<>();

list.add(50);

list.add(45);

list.add(45);

list.add(98);

list.add(32);

List<Integer> collect = list.stream().sorted(Comparator.reverseOrder()).collect(Collectors.toList());

System.out.println("list<Integer>元素倒序：" + collect);

 

打印结果：

list<Integer>元素倒序：[98, 50, 45, 45, 32]

 

3、List的元素的属性值正序

 

Person p1 = new Person("张三", new BigDecimal("50.0"));

Person p2 = new Person("王五", new BigDecimal("25.0"));

Person p3 = new Person("李四", new BigDecimal("68.0"));

Person p4 = new Person("李四", new BigDecimal("17.0"));

Person p5 = new Person("张三", new BigDecimal("45.0"));

List<Person> list = new ArrayList<>();

list.add(p1);

list.add(p2);

list.add(p3);

list.add(p4);

list.add(p5);

list.sort(Comparator.comparing(person -> person.getSalary()));

System.out.println(list);

 

打印结果：

元素的属性值正序：[{name='李四', salary=17.0}, {name='王五', salary=25.0}, {name='张三', salary=45.0}, {name='张三', salary=50.0}, {name='李四', salary=68.0}]

 

4、List的元素的属性值倒序

 

Person p1 = new Person("张三", new BigDecimal("50.0"));

Person p2 = new Person("王五", new BigDecimal("25.0"));

Person p3 = new Person("李四", new BigDecimal("68.0"));

Person p4 = new Person("李四", new BigDecimal("17.0"));

Person p5 = new Person("张三", new BigDecimal("45.0"));

List<Person> list = new ArrayList<>();

list.add(p1);

list.add(p2);

list.add(p3);

list.add(p4);

list.add(p5);

List<Person> collect = list.stream().sorted(Comparator.comparing(Person::getSalary).reversed()).collect(Collectors.toList());

System.out.println("元素的属性值倒序：" + collect);

 

打印结果：

元素的属性值倒序：[{name='李四', salary=68.0}, {name='张三', salary=50.0}, {name='王五', salary=45.0}, {name='张三', salary=45.0}, {name='李四', salary=17.0}]

 

 

 

1. stream流根据年龄正序排序

resultList.stream().sorted(Comparator.comparing(User::getAge))

.collect(Collectors.toList());

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2. stream流根据年龄倒序排序

在正序的基础上增加reversed

 

resultList = resultList.stream().sorted(Comparator.comparing(User::getAge)

.reversed()).collect(Collectors.toList());

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3. stream流先按学生年龄降序排序，年龄相等的话，则按年级升级排序

resultList =  resultList.stream().sorted(Comparator.comparing(User::getAge)

                              .reversed()

                              .thenComparing(Comparator.comparing(User::getGrade))

                    ).collect(Collectors.toList());

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4. stream流先按年龄降序排序，再按年级降序排序

resultList =  resultList.stream().sorted(Comparator.comparing(User::getAge)

                              .reversed()

                              .thenComparing(Comparator.comparing(User::getGrade).reversed())

                    ).collect(Collectors.toList());