JDK8 Collection和Lambda实战

需求描述：电商订单数据处理，根据下?的list1和list2 各10个订单

数据准备

 //总价 35List<VideoOrder> videoOrders1 = Arrays.asList(new VideoOrder("20190242812", "springboot教程", 3),new VideoOrder("20194350812", "微服务SpringCloud", 5),new VideoOrder("20190814232", "Redis教程", 9),new VideoOrder("20190523812", "??开发教程", 9),new VideoOrder("201932324", "百万并发实战Netty", 9));//总价 54List<VideoOrder> videoOrders2 = Arrays.asList(new VideoOrder("2019024285312", "springboot教程", 3),new VideoOrder("2019081453232", "Redis教程", 9),new VideoOrder("20190522338312", "??开发教程", 9),new VideoOrder("2019435230812", "Jmeter压?测试", 5),new VideoOrder("2019323542411", "Git+Jenkins持续集成", 7),new VideoOrder("2019323542424", "Idea全套教程", 21));

public class VideoOrder {private String tradeNo;private int money;private String title;public VideoOrder(String tradeNo, String title, int money) {this.tradeNo = tradeNo;this.title = title;this.money = money;}public String getTradeNo() {return tradeNo;}public void setTradeNo(String tradeNo) {this.tradeNo = tradeNo;}public int getMoney() {return money;}public void setMoney(int money) {this.money = money;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}
}
@Override
public boolean equals(Object obj) {if (obj instanceof VideoOrder) {VideoOrder o1 = (VideoOrder) obj;return title.equals(o1.getTitle());}return super.equals(obj);
}
@Override
public String toString() {return "VideoOrder{" +"money=" + money +", title='" + title + '\'' +'}';
}
@Override
public int hashCode() {return title.hashCode();
}

• 统计出同时被两个?购买的商品列表(交集)

//交集
List<VideoOrder> intersectionList =videoOrders1.stream().filter(videoOrders2::contains).collect(Collectors.toList());System.out.println("交集="+intersectionList);

• 统计出两个?购买商品的差集

//差集1
List<VideoOrder> diffList1 = videoOrders1.stream().filter(obj-
>!videoOrders2.contains(obj)).collect(Collectors.toList());System.out.println("差集1="+diffList1);//差集2List<VideoOrder> diffList2 = videoOrders2.stream().filter(obj-
>!videoOrders1.contains(obj)).collect(Collectors.toList());System.out.println("差集2="+diffList2);

• 统计出全部被购买商品的去重并集

//并集List<VideoOrder> allVideoOrder =videoOrders1.parallelStream().collect(Collectors.toList());allVideoOrder.addAll(videoOrders2);System.out.println("并集 = "+allVideoOrder);//去重并集List<VideoOrder> allVideoOrderDistinct =allVideoOrder.stream().distinct().collect(Collectors.toList());System.out.println("去重并集 = "+allVideoOrderDistinct);

• 统计两个?的分别购买订单的平均价格

//两个订单平均价格
double videoOrderAvg1 =
videoOrders1.stream().collect(Collectors.averagingInt(VideoOrder::getMoney)).doubleValue();
System.out.println("订单列表1平均价格="+videoOrderAvg1);double videoOrderAvg2 =
videoOrders2.stream().collect(Collectors.averagingInt(VideoOrder::getMoney)).doubleValue();
System.out.println("订单列表2平均价格="+videoOrderAvg2)

• 统计两个?的分别购买订单的总价格

//订单总价
int totalMoney1 =
videoOrders1.stream().collect(Collectors.summingInt(VideoOrder::getMoney)).intValue();int totalMoney2 =
videoOrders2.stream().collect(Collectors.summingInt(VideoOrder::getMoney)).intValue();System.out.println("订单列表1总价="+totalMoney1);System.out.println("订单列表2总价="+totalMoney2);