java中應用程式的詳細介紹

偉大軟體的簡易三步驟：

1.確認你的軟體客戶要它做的事。

2.運用基本的OO原則來增加軟體的彈性。

3.努力實現可維護、可重複使用的設計。

專案架構：

Guitar類別：

 1 package com.headfirst.guitar; 2  3 public class Guitar { 4     private String serialNumber, builder, model, type, backWood, topWood; 5     private double price; 6      7     public Guitar(String serialNumber, double price, String builder, 
 8             String model, String type, String backWood, String topWood){ 9         this.serialNumber = serialNumber;10         this.price = price;11         this.builder = builder;12         this.model = model;13         this.type = type;14         this.backWood = backWood;15         this.topWood = topWood;16     }17     18     public String getSerialNumber(){19         return serialNumber;20     }21     public double getPrice(){22         return price;23     }24     public void setPrice(float newPrice){25         this.price = newPrice;26     }27     public String getBuilder(){28         return builder;29     }30     public String getModel(){31         return model;32     }33     public String getType(){34         return type;35     }36     public String getBackWood(){37         return backWood;38     }39     public String getTopWood(){40         return topWood;41     }42 }

Inventory類別：

 1 package com.headfirst.guitar; 2  3 import java.util.Iterator; 4 import java.util.LinkedList; 5 import java.util.List; 6  7 public class Inventory { 8      9     private List guitars;10     11     public Inventory(){12         guitars = new LinkedList();13     }14     15     public void addGuitar(String serialNumber, double price, String builder, String model, String type,16             String backWood, String topWood){17         Guitar guitar = new Guitar(serialNumber, price, builder, 
18                 model, type, backWood, topWood);19         guitars.add(guitar);20     }21     22     public Guitar getGuitar(String serialNumber){23         for(Iterator i = guitars.iterator(); i.hasNext();){24             Guitar guitar = (Guitar) i.next();25             if(guitar.getSerialNumber().equals(serialNumber)){26                 return guitar;27             }28         }29         30         return null;31     }32     33     public Guitar search(Guitar searchGuitar){34         for(Iterator i = guitars.iterator(); i.hasNext();){35             Guitar guitar = (Guitar) i.next();36             String builder = searchGuitar.getBuilder();37             if((builder != null) && (!builder.equals("")) && 
38                     (!builder.equals(guitar.getBuilder())))39                     continue;40             41             String model = searchGuitar.getModel();42             if((model != null) && (!model.equals("")) && 
43                     (!model.equals(guitar.getModel())))44                     continue;45             46             String type = searchGuitar.getType();47             if((type != null) && (!type.equals("")) && 
48                     (!type.equals(guitar.getType())))49                     continue;50             51             String backWood = searchGuitar.getBackWood();52             if((backWood != null) && (!backWood.equals("")) && 
53                     (!backWood.equals(guitar.getBackWood())))54                     continue;55             56             String topWood = searchGuitar.getTopWood();57             if((topWood != null) && (!topWood.equals("")) && 
58                     (!topWood.equals(guitar.getTopWood())))59                     continue;60             return guitar;61         }62         63         return null;64     }65 }

搜尋測試程式碼：

 1 package com.headfirst.guitar; 2  3 public class FindGuitarTester { 4     public static void main(String[] args){ 5         Inventory inventory = new Inventory(); 6         initializeInventory(inventory); 7          8         Guitar whatErinLikes = new Guitar("", 0, "fender", "Stratocastor", "electric", "Alder", "Alder"); 9         10         Guitar guitar = inventory.search(whatErinLikes);11         if(guitar != null){12             System.out.println("Erin, you might like this " + 
13             guitar.getBuilder() + " " + guitar.getModel() + 
14             " " + guitar.getType() + " guitar:\n " + 
15             guitar.getBackWood() + " back and sides,\n " +16             guitar.getTopWood() + " top.\nYou can have it for only $" + 
17             guitar.getPrice() + "!");18         }else{19             System.out.println("Sorry, Erin, we have nothing for you.");20         }21     }22     23     private static void initializeInventory(Inventory inventory){24         inventory.addGuitar("V95693", 1499.95, "Fender", "Stratocastor", "electric", "Alder", "Alder");25     }26 }

執行結果：

為什麼，明明有，為什麼說沒有?

檢查了程式碼，可能搜尋中「fender」的f是小寫，而我們有的「Fender」是大寫。

好，我們對吉他搜尋工具進行第一個改善，去除掉所有String比較：

專案修改架構：

Builder.java：

 1 package com.headfirst.guitar; 2  3 public enum Builder { 4      5     FENDER, MARTIN, GIBSON, COLLINGS, OLSON, RYAN, PRS, ANY; 6      7     public String toString(){ 8         switch(this){ 9         case FENDER:10             return "Fender";11         case MARTIN:12             return "Martin";13         case GIBSON:14             return "Gibson";15         case COLLINGS:16             return "Collings";17         case OLSON:18             return "Olson";19         case RYAN:20             return "Ryan";21         case PRS:22             return "Prs";23         case ANY:24             return "Any";25         default: 
26             return "";27         }28     }29 }

Type.java：

 1 package com.headfirst.guitar; 2  3 public enum Type { 4     ACOUSTIC, ELECTRIC; 5      6     public String toString(){ 7         switch(this){ 8         case ACOUSTIC: 
 9             return "acoustic";10         case ELECTRIC: 
11             return "electric";12         default:13             return "";14         }15     }16 }

###Wood.java：######

 1 package com.headfirst.guitar; 2  3 public enum Wood { 4     INDIAN_ROSEWOOD, BRAZILIAN_ROSEWOOD, ALDER; 5      6     public String toString(){ 7         switch(this){ 8         case INDIAN_ROSEWOOD: 9             return "Indian Rosewood";10         case BRAZILIAN_ROSEWOOD:11             return "Brazilian Rosewood";12         case ALDER:13             return "Alder";14         default:15             return "";16         }17     }18 }

###### #修改FindGuitarTester.java第8行程式碼：###### ######1### Guitar whatErinLikes = ###new### Guitar("", 0, "Builder.FENDER", " Stratocastor", "Type.ELECTRIC", "Wood.ALDER", "Wood.ALDER");### ######修改Inventory.java中search()方法：#######

 1 public Guitar search(Guitar searchGuitar){ 2         for(Iterator i = guitars.iterator(); i.hasNext();){ 3             Guitar guitar = (Guitar) i.next(); 4              5             if(searchGuitar.getBuilder() != guitar.getBuilder()) 6                     continue; 7              8             String model = searchGuitar.getModel().toLowerCase(); 9             if((model != null) && (!model.equals("")) && 
10                     (!model.equals(guitar.getModel().toLowerCase())))11                     continue;12             13             if(searchGuitar.getType() != guitar.getType())14                     continue;15             16             if(searchGuitar.getBackWood() != guitar.getBackWood())17                     continue;18             19             if(searchGuitar.getTopWood() != guitar.getTopWood())20                     continue;21             22             return guitar;23         }24         25         return null;26     }

## ####現在我們擔心的是Model屬性，我們沒有把它做成enum，而且Model沒有辦法限制，所以做不出enum。 ######除此之外：我們修改的地方還有：###############各種變數的型別，用enum的全部替換掉。 ###

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