Java Lambda表达式 List遍历、过滤、排序、去重

package springboot.activiti.demo.utils;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.patch;

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.alibaba.fastjson.JSON;

public class LambdaDemo {
	private static final Logger LOGGER = LoggerFactory.getLogger(LambdaDemo.class);

	public static void main(String[] args) {
		ArrayList arrayList = new ArrayList<>();
		for (int i = 0; i < 10; i++) {
			Person person = new Person("Tom" + i, i + 10, i % 2 == 0 ? 0 : 1);
			arrayList.add(person);
		}
		// 原始数据
		LOGGER.info("===原来arrayList===:{}", JSON.toJSON(arrayList));
		// 重新创建一个List
		List newList = arrayList.stream().collect(Collectors.toList());
		// 循环输出
		newList.stream().forEach(p -> {
			LOGGER.info("=person=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});

		// 只获取男生
		List boys = newList.stream().filter(p -> p.getSex() == 0).distinct().collect(Collectors.toList());
		boys.stream().forEach(p -> {
			LOGGER.info("=boys=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});
		// 获取年龄大于16的
		List more16List = newList.stream().filter(p -> Integer.valueOf(p.getAge()) > 16).distinct()
				.collect(Collectors.toList());
		more16List.stream().forEach(p -> {
			LOGGER.info("=more16List=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});

		// 性别排序
		List sexList = newList.stream().sorted((p1, p2) -> p1.getSex().compareTo(p2.getSex()))
				.collect(Collectors.toList());
		sexList.stream().forEach(p -> {
			LOGGER.info("=sexList=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});

		// 年龄倒序
		Comparator comparator = (p1, p2) -> p1.getAge().compareTo(p2.getAge());
		newList.sort(comparator.reversed());
		newList.stream().forEach(p -> {
			LOGGER.info("=年龄倒序=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});

		// 多条件排序
		newList.sort(Comparator.comparing(Person::getSex).thenComparing(Person::getAge).reversed());
		newList.stream().forEach(p -> {
			LOGGER.info("多条件排序  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});
		// 性别分组
		Map> sexGroup = newList.stream().collect(Collectors.groupingBy(Person::getSex));
		LOGGER.info("sexGroup:{}", sexGroup);

		// 对象去重，必须重写hasCode, equals方法
		Person person1 = new Person("Tom", 10, 0);
		Person person2 = new Person("Tom2", 16, 0);
		Person person3 = new Person("Mary", 15, 1);
		Person person4 = new Person("Tom", 10, 0);
		Person person5 = new Person("Mary", 15, 1);
		arrayList = new ArrayList<>();
		arrayList.add(person1);
		arrayList.add(person2);
		arrayList.add(person3);
		arrayList.add(person4);
		arrayList.add(person5);

		arrayList.stream().forEach(p -> {
			LOGGER.info("=对象去重原来List=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});

		// 去重
		List collect = arrayList.stream().distinct().collect(Collectors.toList());
		collect.stream().forEach(p -> {
			LOGGER.info("=去重后List=  名字:{} -年龄：{} -性别:{}", p.getName(), p.getAge(), p.getSex() == 0 ? "男" : "女");
		});

	}

}

class Person {

	private String name;
	private Integer age;
	private Integer sex;

	public Person(String name, Integer age, Integer sex) {
		super();
		this.name = name;
		this.age = age;
		this.sex = sex;
	}

	public String getName() {
		return name;
	}

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

	public Integer getAge() {
		return age;
	}

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

	public Integer getSex() {
		return sex;
	}

	public void setSex(Integer sex) {
		this.sex = sex;
	}

	@Override
	public String toString() {
		return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((age == null) ? 0 : age.hashCode());
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		result = prime * result + ((sex == null) ? 0 : sex.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Person other = (Person) obj;
		if (age == null) {
			if (other.age != null)
				return false;
		} else if (!age.equals(other.age))
			return false;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		if (sex == null) {
			if (other.sex != null)
				return false;
		} else if (!sex.equals(other.sex))
			return false;
		return true;
	}

}