Java8 lamda表达式快速上手

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(1,"健力宝");
Goods goods2 = new Goods(2,"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);});

}
}

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;
}