Efficient farewell 996, opening the door 2-5 java programming efficient combat: multidimensional parametric conditions

1.1 Key

1.2 Programming Code

 

 

1.1 Key

A new way of thinking: can see Demo ( a method can be one of the parameters is determined according to two parameters )

 

 

1.2 Programming Code

demand:

The method of any one of a parameter can be determined according to two parameters,

 

Commodity same entity class :( 2-3)

 

Goods class :( see filterSkuListByParamB method)

package com.imooc.zhangxiaoxi.lambda.cart;

import java.util.ArrayList;
import java.util.List;

public class CartService {

    /**
     * Anonymous inner classes, there is the risk of memory leaks, not production projects referenced, only to back out of a lambda expression references
     */
    private static List<Sku> skuList = new ArrayList<Sku>(){
        {
            the Add ( new new Sku (2020001, "UAV", 999.00,1,999.00 , SkuCategoryEnum.ELECTRONICS));
            add(new Sku(2020002,"T-shirt",50.00,2,100.00,SkuCategoryEnum.CLOTHING));
            the Add ( new new Sku (2020003, "Of Human Bondage", 30.00,1,30.00 , SkuCategoryEnum.BOOKS));
            the Add ( new new Sku (2020004, "Old Man", 20.00,1,20.00 , SkuCategoryEnum.BOOKS));
            the Add ( new new Sku (2020005, "prove safety and efficient programming", 288.00,1,288.00 , SkuCategoryEnum.BOOKS));
            the Add ( new new Sku (2020006, "bulk shoes", 300.00,1,300.00 , SkuCategoryEnum.CLOTHING));
            the Add ( new new Sku (2020007, "barbell", 2000.00,1,2000.00 , SkuCategoryEnum.SPROTS));
            add(new Sku(2020008,"ThinkPad",5000.00,1,5000.00,SkuCategoryEnum.ELECTRONICS));
        }

    };

    public static List<Sku> getSkuList(){
        return skuList;
    }

    /**
     * versionTestA
     * Find out all electronic products in shopping cart
     *
     * Note for loop
     * 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));
            }
        }
* / 
        Return lElectronicsList;
    }

    /**
     * versionTestB
     * Condition parameters of a single dimension, passed different enum, print out a list of different products
     *
     * Note that the second argument: how the transfer of enumeration class parameters
     *
     *
     * @Param skuList
     * @return
     */
    public static List<Sku> filterSkuListByParam(List<Sku> skuList,SkuCategoryEnum skuCategoryEnum){
        List<Sku> lElectronicsList = new ArrayList<Sku>();
        for (int i=0;i<skuList.size();i++){
            if (skuList.get(i).getSkuCategory().equals(skuCategoryEnum)){
                lElectronicsList.add (skuList.get (i));
            }
        }
        return lElectronicsList;
    }


    /**
     * versionTestC
     * Ran and eggs
     *
     * A method may be any of the parameters is determined according to two parameters,
     *
     * If the flag is true, the judge enumerated class, otherwise, judgment based on the total price
     *
     * @Param skuList
     * @return
     */
    public static List<Sku> filterSkuListByParamB(List<Sku> skuList,SkuCategoryEnum skuCategoryEnum,Double dTotalPrice,boolean flag){
        List<Sku> lElectronicsList = new ArrayList<Sku>();
        for (int i=0;i<skuList.size();i++){
            if ((flag && skuList.get(i).getSkuCategory().equals(skuCategoryEnum))
                ||
                (!flag&&skuList.get(i).getTotalPrice()>dTotalPrice)){
                lElectronicsList.add (skuList.get (i));
            }
        }
        return lElectronicsList;
    }



    /**
     * versionTestD
     * The production does not recommend such an approach would lead to class explosion. Everything is in order to introduce a lambda expression
     *
     * @Param skuList
     * @return
     */
    public static List<Sku> filterSkuListByParamPrediCate(List<Sku> skuList,SkuPrediCate skuPrediCate){
        List<Sku> lElectronicsList = new ArrayList<Sku>();
        for (int i=0;i<skuList.size();i++){
            if (skuPrediCate.test(skuList.get(i))){
                lElectronicsList.add (skuList.get (i));
            }
        }
        return lElectronicsList;
    }



}

 

 

:( same enumeration class 2-3)

 

Test categories:

package com.imooc.zhangxiaoxi.lambda.cart;

import com.alibaba.fastjson.JSON;
import org.junit.Test;

import java.util.List;

public class VersionTestC {

    @Test
   public void filterSkuListByParam(){
       List<Sku> skuList = CartService.getSkuList();
       /*List<Sku> getParamSkuList = CartService.filterSkuListByParamB(skuList,SkuCategoryEnum.BOOKS,null,true);
       System.out.println(JSON.toJSONString(getParamSkuList,true));*/

        List<Sku> getParamSkuList = CartService.filterSkuListByParamB(skuList,null,200.00,false);
        System.out.println(JSON.toJSONString(getParamSkuList,true));

   }

}

 

 

Print log:

[
    {
        "skuCategory":"ELECTRONICS",
        "skuId":2020001,
        "skuName":"无人机",
        "skuPrice":999.0,
        "totalNum":1,
        "totalPrice":999.0
    },
    {
        "skuCategory":"BOOKS",
        "skuId":2020005,
        "skuName":"剑指高效编程",
        "skuPrice":288.0,
        "totalNum":1,
        "totalPrice":288.0
    },
    {
        "skuCategory":"CLOTHING",
        "skuId":2020006,
        "skuName":"大头皮鞋",
        "skuPrice":300.0,
        "totalNum":1,
        "totalPrice":300.0
    },
    {
        "skuCategory":"SPROTS",
        "skuId":2020007,
        "skuName":"杠铃",
        "skuPrice":2000.0,
        "totalNum":1,
        "totalPrice":2000.0
    },
    {
        "skuCategory":"ELECTRONICS",
        "skuId":2020008,
        "skuName":"ThinkPad",
        "skuPrice":5000.0,
        "totalNum":1,
        "totalPrice":5000.0
    }
]

Process finished with exit code 0