摘要：
1.1 重点1.2 代码编程1.1 重点枚举类的使用（SkuCategoryEnum）；JSONtoString方法的使用（测试类）；两种不同list的使用方式（商品服务类）；list的add方法1.2 代码编程需求：程序员双11添加了很多宝贝到购物车，程序员女盆友开始筛选出所有的电子类型的产品商品实体类：packagecom.imooc.zhangxiaoxi.lambda.cart;/
1.1 重点
1.2 代码编程
1.1 重点
枚举类的使用（SkuCategoryEnum）；
JSONtoString方法的使用（测试类）；
两种不同list的使用方式（商品服务类）；
list的add方法
1.2 代码编程
需求：
程序员双11添加了很多宝贝到购物车，程序员女盆友开始筛选出所有的电子类型的产品
商品实体类：
packagecom.imooc.zhangxiaoxi.lambda.cart; /*** 商品类 */ public classSku { private Integer skuId; //商品编号 private String skuName; //商品名称 private Double skuPrice; //商品单价 private Integer totalNum; //商品个数 private Double totalPrice; //商品总价 private Enum skuCategory; //枚举类型 商品类型 publicSku(Integer skuId, String skuName, Double skuPrice, Integer totalNum, Double totalPrice, Enum skuCategory) { this.skuId =skuId; this.skuName =skuName; this.skuPrice =skuPrice; this.totalNum =totalNum; this.totalPrice =totalPrice; this.skuCategory =skuCategory; } publicInteger getSkuId() { returnskuId; } publicString getSkuName() { returnskuName; } publicDouble getSkuPrice() { returnskuPrice; } publicInteger getTotalNum() { returntotalNum; } publicDouble getTotalPrice() { returntotalPrice; } publicEnum getSkuCategory() { returnskuCategory; } }
商品服务类：
packagecom.imooc.zhangxiaoxi.lambda.cart; importjava.util.ArrayList; importjava.util.List; public classCartService { /*** 匿名内部类，有内存泄漏的风险，不在生产项目中引用，只是为了后边引用出来lambda表达式 */ private static List<Sku> skuList = new ArrayList<Sku>(){ { add(new Sku(2020001,"无人机",999.00,1,999.00,SkuCategoryEnum.ELECTRONICS)); add(new Sku(2020002,"T-shirt",50.00,2,100.00,SkuCategoryEnum.CLOTHING)); add(new Sku(2020003,"人生的枷锁",30.00,1,30.00,SkuCategoryEnum.BOOKS)); add(new Sku(2020004,"老人与海",20.00,1,20.00,SkuCategoryEnum.BOOKS)); add(new Sku(2020005,"剑指高效编程",288.00,1,288.00,SkuCategoryEnum.BOOKS)); add(new Sku(2020006,"大头皮鞋",300.00,1,300.00,SkuCategoryEnum.CLOTHING)); add(new Sku(2020007,"杠铃",2000.00,1,2000.00,SkuCategoryEnum.SPROTS)); add(new Sku(2020008,"ThinkPad",5000.00,1,5000.00,SkuCategoryEnum.ELECTRONICS)); } }; public static List<Sku>getSkuList(){ returnskuList; } /*** versionTestA * 找出购物车中所有电子产品 * * 注意for 循环 * for (Sku sku: skuList) 的使用 * @return */ public static List<Sku> getElectronicsSkuList(List<Sku>skuList){ List<Sku> lElectronicsList = new ArrayList<Sku>(); for (Sku sku: skuList){ if(sku.getSkuCategory().equals(SkuCategoryEnum.ELECTRONICS)){ lElectronicsList.add(sku); } } /*for (int i=0;i<skuList.size();i++){ if (skuList.get(i).getSkuCategory().equals(SkuCategoryEnum.ELECTRONICS)){ lElectronicsList.add(skuList.get(i)); } } */ returnlElectronicsList; } }
枚举类：
packagecom.imooc.zhangxiaoxi.lambda.cart; /*** 枚举类的使用 */ public enumSkuCategoryEnum { CLOTHING(10,"服装类"), ELECTRONICS(20,"电子类"), SPROTS(30,"运动类"), BOOKS(40,"图书类"); private Integer code;//码值 private String name;//名称 SkuCategoryEnum(Integer code, String name) { this.code =code; this.name =name; } }
测试类：
packagecom.imooc.zhangxiaoxi.lambda.cart; importcom.alibaba.fastjson.JSON; importorg.junit.Test; importjava.util.List; public classVersionTestA { @Test /*** 筛选出电子类型产品 */ public voidgetElectronicsSkuList(){ List<Sku> skuList =CartService.getSkuList(); List<Sku> electronicList =CartService.getElectronicsSkuList(skuList); System.out.println("electronicList=="+ JSON.toJSONString(electronicList,true)); } }
打印日志：
electronicList==[ { "skuCategory":"ELECTRONICS", "skuId":2020001, "skuName":"无人机", "skuPrice":999.0, "totalNum":1, "totalPrice":999.0}, { "skuCategory":"ELECTRONICS", "skuId":2020008, "skuName":"ThinkPad", "skuPrice":5000.0, "totalNum":1, "totalPrice":5000.0} ] Process finished with exit code 0