Java8 lamda表达式快速上手

1.对比着经典foreach

简单的循环

o相当于foreach中的临时变量,要遍历的list放在句首

list.foreach(o->{你要进行的操作});

package com.company;

import com.entity.Goods;

import java.util.ArrayList;

import java.util.List;

public class Main {

    public static void main(String[] args) {

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

        Goods goods1 = new Goods(,"健力宝");

        Goods goods2 = new Goods(,"伟哥");

        list.add(goods1);

        list.add(goods2);

        for(Goods o: list) { // 外部迭代

            System.out.println(o);

        }

        System.out.println("=============lambda表达式=============");

        list.forEach(o -> {System.out.println(o);});

    }

}

 

2.foreach里面的if功能，即list.stream().filter().foreach()

public List<Photo> buildPhoto() {

        List<Photo> target = new ArrayList<>();

        if (!photoList.isEmpty()) {

            // 根元素

            photoList.stream().filter(photo -> photo.getParentId() == 0).forEach(photo -> {  // 根元素

                List<Photo> children = getChildren(photo);

                photo.setChildren(children);

                target.add(photo);

            });

　　　　　　　// 相当于经典foreach的如下代码

            for (Photo photo:photoList){

                if (photo.getParentId() == 0){

                    List<Photo> children = getChildren(photo);

                    photo.setChildren(children);

                    target.add(photo);

                }

            }

        }

        return target;

    }

如果想深究其原理 参考http://www.cnblogs.com/aoeiuv/p/5911692.html