JAVA學習-第四個代碼模型

標籤：

第四個代碼模型：介面應用

 

在現實生活之中經常會遇見如下的幾種情況：

 

                   · 在一片森林之中有多種樹木；

 

                   · 在商場之中有多種商品；

 

                   · 在一個停車場裡停放著多種車輛，例如：卡車、轎車、>機車、單車。

 

         下面類比以上的一個情境。現在有間超市，在超市之中提供有多種商品，現在要求實現商品的上架銷售和下架的功能，同時可以根據關鍵字查詢出商品的資訊。本程式只要求描述出類的結構即可。

 

 

 

 

範例：定義商品標準

 

interface Goods {         // 商品                public String getName() ;          public double getPrice() ; }

 

範例：定義超市類

 

class SuperMarket {     // 超市          private Link goods ;      // 所有的商品          public SuperMarket() {                    this.goods = new Link() ;      // 準備出存放商品的空間          }          public void insert(Goods g) {         // 增加商品                    this.goods.add(g) ;        // 儲存資料到鏈表          }          public void delete(Goods g) {         // 下架                    this.goods.remove(g) ;  // 從鏈表刪除資料          }          public Link search(String keyWord) {                    Link result = new Link() ;                    Object obj [] = this.goods.toArray() ;                    for (int x = 0 ; x < obj.length ; x ++) {                             Goods gd = (Goods) obj[x] ;                            if (gd.getName().contains(keyWord)) {    // 符合尋找條件                                      result.add(gd) ;    // 儲存商品查詢結果                             }                    }                    return result ;          }          public Link getGoods() {       // 取得本超市之中的所有商品                    return this.goods ;          } }

 

範例：定義商品資料

 

class Cup implements Goods {          private String name ;          private double price ;          public Cup(){}          public Cup(String name,double price){                    this.name = name ;                    this.price = price ;          }          public String getName() {                    return this.name ;          }          public double getPrice() {                    return this.price ;          }          public boolean equals(Object obj) {                    if (obj == null) {                             return false ;                    }                    if (this == obj) {                             return true ;                    }                    if (!(obj instanceof Cup)) {                             return false ;                    }                    Cup cup = (Cup) obj ;                    if (this.name.equals(cup.name) && this.price == cup.price) {                             return true ;                    }                    return false ;          }          public String toString() {                    return "【杯子】名稱 = " + this.name + "，價格：" + this.price ;          } }

class Computer implements Goods {          private String name ;          private double price ;          public Computer(){}          public Computer(String name,double price){                    this.name = name ;                    this.price = price ;          }          public String getName() {                    return this.name ;          }          public double getPrice() {                    return this.price ;          }          public boolean equals(Object obj) {                    if (obj == null) {                             return false ;                    }                    if (this == obj) {                             return true ;                    }                    if (!(obj instanceof Computer)) {                             return false ;                    }                    Computer com = (Computer) obj ;                    if (this.name.equals(com.name) && this.price == com.price) {                             return true ;                    }                    return false ;          }          public String toString() {                    return "【電腦】名稱 = " + this.name + "，價格：" + this.price ;          } }

 

         此時電腦和杯子沒有本質的聯絡，但是他們都屬於商品。

 

public class TestDemo {          public static void main(String args[]) {                    SuperMarket market = new SuperMarket() ;                    market.insert(new Cup("卡通杯",10.0)) ;                    market.insert(new Cup("保溫杯",20.0)) ;                    market.insert(new Cup("冷水杯",32.0)) ;                    market.insert(new Computer("限量版卡通電腦",3200.0)) ;                    market.insert(new Computer("毆打杯紀念電腦",99200.0)) ;                    market.insert(new Computer("不怕水的電腦",39200.0)) ;                    market.delete(new Cup("卡通杯",10.0)) ;                    Object obj [] = market.search("卡通").toArray() ;                    for (int x = 0 ; x < obj.length ; x ++) {                             System.out.println(obj[x]) ;                    }          } }

 

         本程式就是一個典型的面向介面的編程，不同類之間依靠介面進行串連。

 

JAVA學習-第四個代碼模型