Stream

女爷i 2022-12-03 08:43 92阅读 0赞

package com.redisson;
    
    import java.util.ArrayList;
    import java.util.Comparator;
    import java.util.List;
    import java.util.Map;
    import java.util.concurrent.CompletableFuture;
    import java.util.function.Supplier;
    import java.util.stream.Collectors;
    import java.util.stream.Stream;
    
    /**
     * @Description TODO
     * @Date 2020/7/28 9:09
     * @Author zsj
     */
    public class StreamTest {
        public static void main(String[] args) throws Exception {
            List<Person> personList = new ArrayList<Person>();
            Person p1 = new Person();
            p1.setAge(10);
            p1.setName("zlx");
            personList.add(p1);
            p1 = new Person();
            p1.setAge(12);
            p1.setName("jiaduo");
            personList.add(p1);
            p1 = new Person();
            p1.setAge(5);
            p1.setName("ruoran");
            personList.add(p1);
            p1 = new Person();
            p1.setAge(5);
            p1.setName("rxxx");
            personList.add(p1);
    
            p1 = new Person();
            p1.setAge(10);
            p1.setName("iii");
            personList.add(p1);
    
            p1 = new Person();
            p1.setAge(22);
            p1.setName("iiizz");
            personList.add(p1);
    
    
    
    //根据age对list分组
            Map<Integer,List<Person>> groupByAge = personList.parallelStream().collect(Collectors.groupingBy(Person::getAge));
    //根据age进行排序（reserve倒序）
    
            List<Person> peopleListSorted = personList.parallelStream().sorted(Comparator.comparing(Person::getAge).reversed()).collect(Collectors.toList());
    
    
    //提取age,并排序
            List<Integer> ageList = personList.stream().map(Person::getAge).distinct().sorted().collect(Collectors.toList());
    
            //提取年龄大于20的people
            List<Person> olderThan20 = personList.parallelStream().filter(e->e.getAge() > 20).collect(Collectors.toList());
    
            String str = Stream.of("A", "B", "C", "D").reduce("-", String::concat);
            String str2 = Stream.of("A", "B", "C", "D").collect(Collectors.joining("-"));
    
            int sum = Stream.of(1, 2, 3, 4).reduce(Integer::sum).get();
            int sum2 = Stream.of(1, 2, 3, 4).reduce(7, Integer::sum);
    
            List<String> names = personList.parallelStream().filter(person -> person.getAge() > 9)
                    .map(person -> person.getName()).collect(Collectors.toList());
            names.forEach(ii -> {
                System.out.println(ii);
            });
    
        }
    
    
    }