Java8的stream().map()用法详解

package com.base.labguage.java8;

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

public class StreamMap {

    private static class People{
        private String name;
        private Integer age;
        private String address;
		
        // 只给出构造方法，忽略get/set细节
        public People(String name, Integer age, String address) {
            this.name = name;
            this.age = age;
            this.address = address;
        }

    }

    public static class PeoplePub{
        
        private String name;
        private Integer age;

        // 只给出构造方法，忽略get/set细节
        public PeoplePub(String name, Integer age) {
            this.name = name;
            this.age = age;
        }
        
        // 重写toString方法
        public String toString(){
            return "(" + this.name + "," + this.age + ")";

        }

    }

    public static void main(String[] args) {

        List<People> peoples = Arrays.asList(
                new People("zs", 25, "cs"),
                new People("ls", 28, "bj"),
                new People("ww", 23, "nj")
        );

        // List -> String
        List<String> names = peoples.stream().map(p -> p.getName()).collect(Collectors.toList());
        // stream流实现英文字母转大写
        List<String> upNames = names.stream().map(String::toUpperCase).collect(Collectors.toList());
        // stream流实现数字乘倍数
        List<Integer> ages = peoples.stream().map(p -> p.getAge() * 2).collect(Collectors.toList());
        // list - > new List
        List<PeoplePub> peoplePubs = peoples.stream().map(p -> {
            return new PeoplePub(p.getName(), p.getAge());
        }).collect(Collectors.toList());

        System.out.println("to print upnames List : " + upNames);
        System.out.println("to print ages List : " + ages);
        System.out.println("to print new people List" + peoplePubs.toString());

    }

}