利用stream sorted进行降序排序

public static void main(String[] args) {
  List<Map<String, Object>> list = Lists.newArrayList();
  Map<String, Object> map = Maps.newHashMap();
  map.put("id", 1);
  map.put("value", 20);
  list.add(map);
  map = Maps.newHashMap();
  map.put("id", 2);
  map.put("value", 80);
  list.add(map);
  map = Maps.newHashMap();
  map.put("id", 3);
  map.put("value", 21);
  list.add(map);
  map = Maps.newHashMap();
  map.put("id", 4);
  map.put("value", 28);
  list.add(map);
  System.out.println("原始数据："+list);
  //根据value进行排序 得到升序排列
  list.sort(Comparator.comparing(h -> ConvertUtil.obj2Integer(h.get("value"))));
  //颠倒排序，变为降序排列
  Collections.reverse(list);
  //截取前3个
  System.out.println("结果"+list.subList(0, 3));
 }

List<Map<String, Object>>result = list.stream().sorted((h1, h2) -> 
//降序
ConvertUtil.obj2Integer(h2.get("value")).compareTo(ConvertUtil .obj2Integer(h1.get("value"))))
 //前3个
    .limit(3)
    //终止流
    .collect(Collectors.toList());
 System.out.println("流结果"+result );

[{id=1, value=20}, {id=2, value=80}, {id=3, value=21}, {id=4, value=28}]

[{id=2, value=80}, {id=4, value=28}, {id=3, value=21}]

package com.it.test;
import java.util.ArrayList; 
import java.util.List;
import java.util.stream.Collectors; 
public class StreamTest {
 public static void main(String[] args) {
  List<Integer> integers = new ArrayList<>();
  integers.add(9);
  integers.add(2);
  integers.add(0);
  integers.add(4);
  integers.add(8);
  List<Integer> collect = integers.stream().sorted().collect(Collectors.toList()); //自然排序
 }
}

package com.it.test;
import java.util.ArrayList; 
import java.util.List;
import java.util.stream.Collectors; 
public class StreamTest {
 public static void main(String[] args) {
  List<String> strings = new ArrayList<>();
  strings.add("aa");
  strings.add("b");
  strings.add("aac");
  strings.add("bb");
  strings.add("abb");
  List<String> collect1 = strings.stream().sorted().collect(Collectors.toList());
  System.out.println(collect1.toString());
 }
}

package com.it.pojo; 
import java.util.Comparator;
import java.util.Objects; 
@Data
@NoArgsConstructor
@ToString
public class Person {
 private String name;
 private Integer age;
}
 

package com.it.test;
import java.util.ArrayList; 
import java.util.List;
import com.it.pojo.Person; 
import java.util.Comparator;
import java.util.stream.Collectors; 
public class StreamTest {
 public static void main(String[] args) {
  Person person1 = new Person();
  person1.setAge(21);
  person1.setName("21");
 
  Person person2 = new Person();
  person2.setAge(19);
  person2.setName("19");
 
  Person person3 = new Person();
  person3.setAge(19);
  person3.setName("20");
 
  Person person4 = new Person();
  person4.setAge(20);
  person4.setName("20");
 
  Person person5 = new Person();
  person5.setAge(19);
  person5.setName("18");
  
  List<Person> people = new ArrayList<>();
  people.add(person1);
  people.add(person2);
  people.add(person3);
  people.add(person4);
  people.add(person5);
  
  List<Person> collect1 = people.stream().sorted((Comparator.comparing(Person::getAge))).collect(Collectors.toList());//只根据年龄排序，升序
  System.out.println(collect2);
  
   List<Person> collect2 = people.stream().sorted((Comparator.comparing(Person::getAge)).reversed()).collect(Collectors.toList());//只根据年龄排序，降序
  System.out.println(collect2);
  
  List<Person> collect3 = people.stream().sorted((Comparator.comparing(Person::getAge)).thenComparing(Comparator.comparing(Person::getName))).collect(Collectors.toList());//先根据年龄进行排序，遇见相同的，然后根据姓名进行排序，都升序
  System.out.println(collect3);
 
   List<Person> collect4 = people.stream().sorted((Comparator.comparing(Person::getAge)).thenComparing(Comparator.comparing(Person::getName)).reversed()).collect(Collectors.toList());/先根据年龄进行排序，遇见相同的，然后根据姓名进行排序，降序【都降序】
  System.out.println(collect4);
 
  List<Person> collect5 = people.stream().sorted(Comparator.comparing(Person::getAge).reversed().thenComparing(Comparator.comparing(Person::getName)).reversed()).collect(Collectors.toList());//年龄升序，姓名降序
  System.out.println(collect5);
  
  List<Person> collect6 = people.stream().sorted(Comparator.comparing(Person::getAge).reversed().thenComparing(Comparator.comparing(Person::getName))).collect(Collectors.toList());//根据年龄降序，姓名升序
  System.out.println(collect6);
 }
}