伟大软件的简易三步骤：
1.确认你的软件客户要它做的事。
2.运用基本的OO原则来增加软件的灵活性。
3.努力实现可维护、可重用的设计。
项目架构：
Guitar类：
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类：
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 }
搜寻测试代码：
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 }
运行结果：
为什么，明明有，为什么说没有?
检查了代码，可能搜寻中“fender”的f是小写，而我们有的“Fender”是大写。
好，我们对吉他搜索工具进行第一个改善，去除掉所有String比较：
项目修改架构：
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行代码：
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 }
现在我们担心的是Model属性，我们没有把它做成enum，并且Model没有办法限制，所以做不出enum。
除此之外：我们修改的地方还有：
各种变量的类型，用enum的全部替换掉。
时间： 2024-10-14 10:34:21