代码

package com.jianshu;

import lombok.Data;

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

/**
 * stream 对象分组
 *
 * @author archer
 * @since 2022/12/28 8:51
 */
public class StreamGroup {

    public static void main(String[] args) {
        List<Person> personList = new ArrayList<>();
        Person person1 = new Person(1, "张三");
        Person person2 = new Person(0, "李四");
        Person person3 = new Person(1, "王五");
        Person person4 = new Person(1, "马六");
        personList.add(person1);
        personList.add(person2);
        personList.add(person3);
        personList.add(person4);

        List<Integer> sexes = personList.stream().map(Person::getSex).collect(Collectors.toList());

        System.out.println("全部值：");
        sexes.forEach(System.out::println);

        sexes = personList.stream().map(Person::getSex).distinct().collect(Collectors.toList());

        System.out.println("去重后的值：");
        sexes.forEach(System.out::println);

    }

    @Data
    private static class Person {

        /**
         * 初始化对象
         *
         * @param sex  性别
         * @param name 姓名
         */
        public Person(Integer sex, String name) {
            this.sex = sex;
            this.name = name;
        }

        /**
         * 性别
         */
        private Integer sex;

        /**
         * 姓名
         */
        private String name;
    }
}

输出结果

全部值：
1
0
1
1
去重后的值：
1
0