package com.doinb;

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

import lombok.experimental.Accessors;

import lombok.extern.slf4j.Slf4j;

import java.util.*;

import java.util.function.Function;

import java.util.stream.Collectors;

@Slf4j

public class LambdaTest {

public static void main(String[] args) {

lambdaTest();

}

public static void lambdaTest() {

LambdaTest lambdaTest = new LambdaTest();

List<Student> list = lambdaTest.getStudents();

List<Demo> demos = new ArrayList<>();

// 原始数据

System.out.println("原始数据 组装list<demo>*******************");

demos = list.stream().map(student -> new Demo(student.getName(), student.getAge(), student.getSex())).collect(Collectors.toList());

demos.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + " 性别 " + demo.getSex() + ",");

});

// 只取sex为0

System.out.println("只取sex为0**************** 去重");

List<Demo> demorm = demos.stream().filter(demo -> demo.getSex() == 0).distinct().collect(Collectors.toList());

demorm.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + " 性别 " + demo.getSex() + ",");

});

System.out.println("只取sex为0**************** 非去重");

demos.stream().filter(demo -> demo.getSex() == 0).collect(Collectors.toList())

.forEach(demo -> System.out.println("年龄 " + demo.getAge() + " 性别 " + demo.getSex() + ","));

// 筛选年龄大于12岁

System.out.println("筛选年龄大于12岁的*************");

List<Demo> demoFilter = demos.stream().filter(demo -> Integer.valueOf(demo.getAge()) > 12).collect(Collectors.toList());

demoFilter.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + " 性别 " + demo.getSex() + ",");

});

// 排序

System.out.println("年龄排序******************");

// jdk1.8 特性 Comparator.comparing(Demo::getAge)是静态方法直接引用; Demo::getAge代表调用getAge方法

List<Demo> demoSort = demos.stream().sorted(Comparator.comparing(Demo::getAge)).collect(Collectors.toList());

demoSort.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + ",");

});

// 倒序

System.out.println("年龄倒序****************");

ArrayList<Demo> demoArray = (ArrayList<Demo>) demos;

Comparator<Demo> comparator = Comparator.comparing(Demo::getAge);

demos.sort(comparator.reversed());

//or

demos.sort(Comparator.comparing(Demo::getAge).reversed());

demos.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + ",");

});

// 多条件正序

System.out.println("多条件排序正序****************");

demoArray.sort(Comparator.comparing(Demo::getSex).thenComparing(Demo::getAge));

demoArray.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + " 性别 " + demo.getSex() + ",");

});

// 多条件倒序

System.out.println("多条件排序倒序 sex 倒序****************");

demoArray.sort(Comparator.comparing(Demo::getSex).reversed().thenComparing(Demo::getAge));

demoArray.forEach(demo -> {

System.out.println("年龄 " + demo.getAge() + " 性别 " + demo.getSex() + ",");

});

// 按照年龄分组

System.out.println("根据age分组结果为Map****************");

Map<String, List<Demo>> demoOder = demos.stream().collect(Collectors.groupingBy(Demo::getAge));

System.out.println(demoOder);

// 收集为map

System.out.println("收集为map**************");

// toMap有个重载方法，可以传入一个合并的函数来解决key冲突问题：(key1, key2) -> key2), 只是简单的使用后者覆盖前者来解决key重复问题。

// toMap还有另一个重载方法，可以指定一个Map的具体实现，来收集数据：(key1, key2) -> key2, LinkedHashMap::new)

// demos.stream().collect(Collectors.toMap(Demo::getAge, Function.identity(), (k1, k2) -> k2, HashMap::new))

demos.stream().collect(Collectors.toMap(Demo::getName,Function.identity(), (k1, k2) -> k2, HashMap::new))

.forEach((key, value) -> System.out.println(key + "=" + value));

}

private List<Student> getStudents() {

List<Student> list = new ArrayList<>();

list.add(new Student().setAge("12").setSex(0).setName("张三丰"));

list.add(new Student().setAge("13").setSex(2).setName("赵无极"));

list.add(new Student().setAge("11").setSex(1).setName("冯绍峰"));

list.add(new Student().setAge("18").setSex(1).setName("杨幂"));

list.add(new Student().setAge("20").setSex(0).setName("tfboy"));

list.add(new Student().setAge("18").setSex(2).setName("李逵"));

list.add(new Student().setAge("18").setSex(2).setName("黑人"));

list.add(new Student().setAge("23").setSex(3).setName("tfboy"));

return list;

}

@Data

@NoArgsConstructor

@AllArgsConstructor

@Accessors(chain = true)

static class Demo {

private String name;

private String age;

private Integer sex;

}

@Data

@Accessors(chain = true)

static class Student {

private String name;

private String age;

private Integer sex;

}

}