1、基础类

package cn.fqy.test;

public class Student {

    // 名称
    private String name;

    // 性别
    private String gender;

    // 年龄
    private Integer age;

    public Student(String name, String gender, Integer age) {
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", age=" + age +
                '}';
    }
}

2、测试类

package cn.fqy.test;

import java.util.ArrayList;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import static java.util.stream.Collectors.averagingInt;
import static java.util.stream.Collectors.partitioningBy;

public class ListSort {
    public static void main(String[] args) {
        // 测试数据
        List<Student> list = new ArrayList<>();
        list.add(new Student("李明","男",18));
        list.add(new Student("李飞","男",17));
        list.add(new Student("张丽","女",17));
        list.add(new Student("张艳","女",20));
        list.add(new Student("王朋","男",18));
        list.add(new Student("陈晴","女",18));
        list.add(new Student("王菲","女",19));
        list.add(new Student("李雷","男",20));

        // 查找性别为男的学生
        List<Student> boys = list.stream().filter(s->"男".equals(s.getGender())).collect(Collectors.toList());

        // map的key值true为男，false为女的集合
        Map<Boolean, List<Student>> map1 = list.stream().collect(partitioningBy(student -> student.getGender().equals("男")));

        // 求性别为男的学生总岁数
        Integer sum = list.stream().filter(s -> "男".equals(s.getGender())).mapToInt(Student::getAge).sum();

        // 按性别进行分组统计人数
        Map<String, Integer> map2 = list.stream().collect(Collectors.groupingBy(Student::getGender, Collectors.summingInt(p -> 1)));

        // 判断是否有年龄大于25岁的学生
        boolean check = list.stream().anyMatch(student -> student.getAge() > 25);

        // 获取所有学生的姓名集合
        List<String> list2 = list.stream().map(Student::getName).collect(Collectors.toList());

        // 求所有人的平均年龄
        double avg = list.stream().collect(averagingInt(Student::getAge));

        // 求年龄最大的学生
        Student s = list.stream().reduce((student, student2) -> student.getAge() > student2.getAge() ? student:student2).get();

        // 按照年龄从小到大排序
        List<Student> l3 = list.stream().sorted((s1, s2) -> s1.getAge().compareTo(s2.getAge())).collect(Collectors.toList());

        // 获取所有的名字，输出一个字符串
        String str = list.stream().map(Student::getName).collect(Collectors.joining(",", "[", "]"));

        System.out.println(str);

        // 获取年龄的最大值、最小值、平均值、求和等等
        IntSummaryStatistics intSummaryStatistics = list.stream().mapToInt(Student::getAge).summaryStatistics();

        System.out.println(intSummaryStatistics);
    }
}