package test9;

import java.util.Collections;

import java.util.HashSet;

import java.util.Map;

import java.util.Set;

import java.util.TreeMap;

import java.util.function.Function;

import java.util.stream.Collectors;

import java.util.stream.Stream;

public class CollectorsTest {

    public static void main(String[] args) {

        Map<String, Person> map = Stream

                .of(Person.valueOf("小明", '男', 18), Person.valueOf("小丽", '女', 16), Person.valueOf("小王", '男', 19))

                .collect(Collectors.toMap(Person::getName, Function.identity()));

        System.out.println("map:" + map);

        Map<String, Person> map2 = Stream

                .of(Person.valueOf("小明", '男', 18), Person.valueOf("小丽", '女', 16), Person.valueOf("小明", '男', 19))

                .collect(Collectors.toMap(Person::getName, Function.identity(), (x, y) -> y));

        System.out.println("如果有2个key重复了就用新的，‘y’,想用旧的代替就用'x',自己选择，map2:" + map2);

        /*

         * 需求：要求将已有的国家名为key, 人名为value(当然也可以是对象)集合。

         */

        Map<String, Set<String>> map3 = Stream

                .of(Person.valueOf("China", "小明"), Person.valueOf("China", "小丽"), Person.valueOf("us", "Jack"),

                        Person.valueOf("us", "Alice"))

                .collect(Collectors.toMap(Person::getCountry, p -> Collections.singleton(p.getName()), (x, y) -> {

                    Set<String> set = new HashSet<>(x);

                    set.addAll(y);

                    return set;

                }));

        System.out.println("map3:" + map3);

        // 将所有元素检查key不重复且最终包装成一个TreeMap对象

        Map<String, String> map4 = Stream.of(Person.valueOf("China", "小明"), Person.valueOf("Chinsa", "小丽"), Person.valueOf("us", "Jack"),

            Person.valueOf("uss", "Alice"))

            .collect(Collectors.toMap(

                Person::getCountry,

                Person::getName, (x, y) ->

                {

                    throw new IllegalStateException();

                },TreeMap::new));

        System.out.println(map4);

    }

}

class Person {

    private String country;

    private String name;

    private Character sex;

    private Integer age;

    public String getCountry() {

        return country;

    }

    public void setCountry(String country) {

        this.country = country;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public Character getSex() {

        return sex;

    }

    public void setSex(Character sex) {

        this.sex = sex;

    }

    public Integer getAge() {

        return age;

    }

    public void setAge(Integer age) {

        this.age = age;

    }

    @Override

    public String toString() {

        return "name:" + name + "sex:" + sex + "age" + age;

    }

    public static Person valueOf(String country, String name) {

        Person person = new Person();

        person.country = country;

        person.name = name;

        return person;

    }

    public static Person valueOf(String name, Character sex, Integer age) {

        Person person = new Person();

        person.name = name;

        person.sex = sex;

        person.age = age;

        return person;

    }

}