第十一章集合、比较和转换

集合类（Collection Classes）一般用于处理对象列表，其功能比简单数组要多，功能大多是通过实现System.Collections名称空间中的几口而获得的，因此集合的语法已经标准化了。
ArrayList集合可以用AddRange()方法一次添加好几个项。这个方法接受带有ICollection接口的任何对象，包括数组（Array）。
（InsertRange()添加到指定位置、IndexOf()获得索引）
简单数组（Array）是强类型化的，可以直接访问它们所包含的项类型，所以可以直接调用项的方法;
ArrayList集合是System.Object对象的集合，所以必须对所有的项进行数据类型转换。p245
索引符（indexer）是一种特殊类型的属性，可以把它添加到一个类中，以提供类似于数组的访问。

定义集合：

View Code

 1 public class Animals : System.Collections.CollectionBase
 2     {
 3         public void Add(Animal newAnimal)
 4         {
 5             List.Add(newAnimal);
 6         }
 7         public void Remove(Animal oldAnimal)
 8         {
 9             List.Remove(oldAnimal);
10         }
11         public Animals()
12         { }
13         public Animal this[int animalIndex]
14         {
15             get 
16             {
17                 return (Animal)List[animalIndex];
18             }
19             set 
20             {
21                 List[animalIndex] = value;
22             }
23         }
24     }

View Code

 1 class AnimalsDic : DictionaryBase
 2     {
 3         public void Add(string newID, Animal newAnimal)
 4         {
 5             Dictionary.Add(newID, newAnimal);
 6         }
 7         public void Remove(string animalID)
 8         {
 9             Dictionary.Remove(animalID);
10         }
11         public AnimalsDic() { }
12         public Animal this[string animalID]
13         {
14             get { return this[animalID]; }
15             set { this[animalID] = value; }
16         }
17     }

迭代器：它是一个代码块，按顺序提供了要在foreach循环中使用的所有值。使用yield关键字选择要在foreach循环中使用的值（yield return value;）。

View Code

 1 class Odd
 2     {
 3         private long min;
 4         private long max;
 5 
 6         public Odd()
 7             : this(1, 200)
 8         { }
 9 
10         public Odd(long minnum, long maxnum)
11         {
12             this.min = minnum < 1 ? 1 : minnum;
13             this.max = maxnum;
14         }
15 
16         public IEnumerator GetEnumerator()
17         {
18             for (long possibleOdd = min; possibleOdd <= max; possibleOdd++)
19             {
20                 if (possibleOdd%2!=0)
21                 {
22                     yield return possibleOdd;
23                 }
24             }
25         }
26     }

View Code

 1 class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5             Odd prime = new Odd(1, 1000);
 6             foreach (long item in prime)
 7             {
 8                 Console.Write(item+" ");
 9             }
10             Console.ReadKey();
11         }
12     }

View Code

 1 class AnimalsDic : DictionaryBase
 2     {
 3         public void Add(string newID, Animal newAnimal)
 4         {
 5             Dictionary.Add(newID, newAnimal);
 6         }
 7         public void Remove(string animalID)
 8         {
 9             Dictionary.Remove(animalID);
10         }
11         public AnimalsDic() { }
12         public Animal this[string animalID]
13         {
14             get { return this[animalID]; }
15             set { this[animalID] = value; }
16         }
17         public new IEnumerator GetEnumerator()
18         {
19             foreach (object animal in Dictionary.Values)
20             {
21                 yield return (Animal)animal;
22             }
23         }
24     }

View Code

 1 class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5             AnimalsDic animalDic = new AnimalsDic();
 6             animalDic.Add("1", new Cow("Gen"));
 7             animalDic.Add("2", new Chicken("Ken"));
 8             foreach (Animal animal in animalDic)
 9             {
10                 Console.WriteLine(animal.Name);
11             }
12             Console.ReadKey();
13         }
14     }

深复制：（有时这是一个递归的过程）实现ICloneable接口，该接口有一个方法Clone()，不带参数，返回Object。

View Code

 1     //浅复制
 2     class Program
 3     {
 4         static void Main(string[] args)
 5         {
 6             Cloner mySource = new Cloner(5);
 7             Cloner myTarget = mySource.GetCopy() as Cloner;
 8             Console.WriteLine(myTarget.MyContent.Val.ToString());
 9             mySource.MyContent.Val = 2;
10             Console.WriteLine(myTarget.MyContent.Val.ToString());
11             Console.ReadKey();
12         }
13     }
14     class Content
15     {
16         public int Val;
17     }
18     class Cloner
19     {
20         public Content MyContent = new Content();
21 
22         public Cloner(int newVal)
23         {
24             MyContent.Val = newVal;
25         }
26         public object GetCopy()
27         {
28             return MemberwiseClone();
29         }
30     }

View Code

 1     //深复制
 2     class Program
 3     {
 4         static void Main(string[] args)
 5         {
 6             Cloner mySource = new Cloner(5);
 7             Cloner myTarget = (Cloner)mySource.Clone();
 8             Console.WriteLine(myTarget.MyContent.Val.ToString());
 9             mySource.MyContent.Val = 2;
10             Console.WriteLine(myTarget.MyContent.Val.ToString());
11             Console.ReadKey();
12         }
13     }
14     class Content : ICloneable
15     {
16         public int Val;
17         public object Clone()
18         {
19             Content clonedContent = new Content();
20             clonedContent.Val = this.Val;
21             return clonedContent;
22         }
23     }
24     class Cloner : ICloneable
25     {
26         public Content MyContent = new Content();
27 
28         public Cloner(int newVal)
29         {
30             MyContent.Val = newVal;
31         }
32         public Cloner()
33         {        }
34         public object Clone()
35         {
36             Cloner clonedCloner = new Cloner();
37             clonedCloner.MyContent = (Content)this.MyContent.Clone();
38             return clonedCloner;
39         }
40     }

类型比较 : is运算符

View Code

1             if (1 is int)
2             {
3                 Console.WriteLine("loss for words");
4             }

运算符重载

View Code

 1 class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5             MyClass class1 = new MyClass();
 6             class1.val = 1;
 7             MyClass class2 = new MyClass();
 8             class2.val = 2;
 9             MyClass class3 = new MyClass();
10             class3 = class1 + class2;
11             Console.WriteLine(class3.val.ToString());
12             Console.ReadKey();
13         }
14     }
15 
16     public class MyClass
17     {
18         public int val;
19 
20         public static MyClass operator +(MyClass class1, MyClass class2)
21         {
22             MyClass class3 = new MyClass();
23             class3.val = class1.val + class2.val;
24             return class3;
25         }
26     }

比较:
●IComparable：在要比较的对象的类中实现，可以比较该对象和另一个对象。
●Icomparer：在一个单独的类中实现，可以比较任意两个对象。

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Collections;
 6 
 7 namespace Compare
 8 {
 9     class Program
10     {
11         static void Main(string[] args)
12         {
13             ArrayList list = new ArrayList();
14             list.Add(new Person("sam", 24));
15             list.Add(new Person("dean", 26));
16             list.Add(new Person("cass", 1500));
17             list.Add(new Person("bob", 53));
18 
19             list.Sort();//Person 默认 Age 排序
20 
21             foreach (var item in list)
22             {
23                 Person p = item as Person;
24                 Console.WriteLine("{0}:{1}", p.Name, p.Age);
25             }
26 
27             Console.WriteLine();
28 
29             list.Sort(new PersonCompareByName());
30 
31              foreach (var item in list)
32             {
33                 Person p = item as Person;
34                 Console.WriteLine("{0}:{1}", p.Name, p.Age);
35             }
36 
37             Console.ReadKey();
38         }
39     }
40 
41     public class Person : IComparable
42     {
43         public string Name;
44         public int Age;
45 
46         public Person(string name, int age)
47         {
48             this.Name = name;
49             this.Age = age;
50         }
51 
52         public int CompareTo(object obj)
53         {
54             if (obj is Person)
55             {
56                 return this.Age - ((Person)obj).Age;
57             }
58             else
59             {
60                 throw new ArgumentException("xxx");
61             }
62         }
63     }
64 
65     public class PersonCompareByName : IComparer
66     {
67         public int Compare(object obj1, object obj2)
68         {
69             if (obj1 is Person && obj2 is Person)
70             {
71                 return Comparer.Default.Compare(((Person)obj1).Name, ((Person)obj2).Name);
72             }
73             else
74             {
75                 throw new ArgumentException("xxx");
76             }
77         }
78     }
79 }

转换：重载转换运算符，在不相关的类型之间转换。

View Code

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 
 6 namespace Convert
 7 {
 8     class Program
 9     {
10         static void Main(string[] args)
11         {
12             MyClass1 myClass1 = new MyClass1(10);
13             MyClass2 myClass2 = myClass1;
14 
15             Console.WriteLine(myClass2.val.ToString());
16 
17             //MyClass2 myClass2_2 = new MyClass2(10000000000);
18             MyClass2 myClass2_2 = new MyClass2(10000);
19             MyClass1 myClass1_2 = new MyClass1();
20             
21             try
22             {
23                 myClass1_2 = (MyClass1)myClass2_2;
24             }
25             catch (Exception ex)
26             {
27                 Console.WriteLine(ex.Message);
28             }
29 
30             Console.WriteLine(myClass1_2.val.ToString());
31 
32             Console.ReadKey();
33         }
34     }
35 
36     public class MyClass1
37     {
38         public int val;
39 
40         public MyClass1()
41         { }
42 
43         public MyClass1(int val)
44         {
45             this.val = val;
46         }
47 
48         public static implicit operator MyClass2(MyClass1 myClass1)
49         {
50             MyClass2 myClass2 = new MyClass2();
51             myClass2.val = myClass1.val;
52             return myClass2;
53         }
54     }
55     public class MyClass2
56     {
57         public double val;
58 
59         public MyClass2()
60         { }
61 
62         public MyClass2(double val)
63         {
64             this.val = val;
65         }
66 
67         public static explicit operator MyClass1(MyClass2 myClass2)
68         {
69             MyClass1 myClass1 = new MyClass1();
70             myClass1.val = System.Convert.ToInt32(myClass2.val);
71             return myClass1;
72         }
73     }
74 
75 
76 }

as运算符：<operand> as <type>，要注意的是，如果不能从<operand>转换为<type>，则表达式的结果就是null，而不会抛异常。

posted @ 2012-08-01 09:41 David Huang 阅读(213) 评论(0) 编辑收藏举报

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第十一章 集合、比较和转换

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第十一章集合、比较和转换