public class Java8Test {

public  static  void  main(String[] args) {

Person p1 =  new  Person( "麻子" ,  31 );

Person p2 =  new  Person( "李四" ,  20 );

Person p3 =  new  Person( "王五" ,  26 );

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

personList.add(p1);

personList.add(p2);

personList.add(p3);

//java8遍历

personList.forEach(p -> System.out.println(p.getAge()));

//按照person的 age进行排序

//方法一

personList.sort((o1, o2) -> o1.getAge().compareTo(o2.getAge()));  //正序

personList.sort((o1, o2) -> o2.getAge().compareTo(o1.getAge()));  //倒序

//方法二

personList.sort(Comparator.comparing(Person::getAge));  // 正序

personList.sort(Comparator.comparing(Person::getAge).reversed());  // 倒序

//遍历

personList.forEach(p -> System.out.println(p.getAge()));

System.out.println( "========================================" );

//获取年龄最大的Person

Person maxAgePerson = personList.stream().max(Comparator.comparing(Person::getAge)).get();

System.out.println(maxAgePerson.getAge());

System.out.println( "========================================" );

//获取年龄最小的Person

Person minAgePerson = personList.stream().min(Comparator.comparing(Person::getAge)).get();

System.out.println(minAgePerson.getAge());

//过滤出年龄是20的person，想过滤出什么条件的都可以

List<Person> personList1 = personList.stream().filter(person -> person.getAge() ==  20 ).collect(Collectors.toList());

//统计出年龄等于20的个数

long  count = personList.stream().filter(person -> person.getAge() ==  20 ).count();

//获得年龄的平均值

double  asDouble = personList.stream().mapToInt(person -> person.getAge()).average().getAsDouble();

//获得年龄的求和

int  sum = personList.stream().mapToInt(person -> person.getAge()).sum();

}

}