定義一個(gè)借口，接口封裝了矩形的長(zhǎng)和寬，而且還包含一個(gè)自定義的方法以計(jì)算矩形的面積。然后定義一個(gè)類，繼承自該接口，在該類中實(shí)現(xiàn)接口中自定義方法。

 1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5  6 namespace Test06 7 { 8     interface ImyInterface 9     {10         /// <summary>11         /// 長(zhǎng)12         /// </summary>13         int Width14         {15             get;16             set;17         }18         /// <summary>19         /// 寬20         /// </summary>21         int Height22         {23             get;24             set;25         }26         /// <summary>27         /// 計(jì)算矩形面積28         /// </summary>29         int Area();////////  int Area(int Width, int Height);  30     }31     class PRogram : ImyInterface//繼承自接口32     {33         private int width = 0;34         private int height = 0;35         /// <summary>36         /// 長(zhǎng)37         /// </summary>38         public int Width39         {40             get41             {42                 return width;43             }44             set45             {46                 width = value;47             }48         }49         /// <summary>50         /// 寬51         /// </summary>52         public int Height53         {54             get55             {56                 return height;57             }58             set59             {60                 height = value;61             }62         }63         /// <summary>64         /// 計(jì)算矩形面積65         /// </summary>66         public int Area(int Width,int Height)67         {68             return Width * Height;69         }70         static void Main(string[] args)71         {72             Program program = new Program();//實(shí)例化Program類對(duì)象73             ImyInterface imyinterface = program;//使用派生類對(duì)象實(shí)例化接口ImyInterface74             imyinterface.Width = 5;//為派生類中的Width屬性賦值75             imyinterface.Height = 3;//為派生類中的Height屬性賦值76             Console.WriteLine("矩形的面積為：" + imyinterface.Area(3,5));77         }78     }79 }

下面是正確的：

 1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5  6 namespace Test06 7 { 8     interface ImyInterface 9     {10         /// <summary>11         /// 長(zhǎng)12         /// </summary>13         int Width14         {15             get;16             set;17         }18         /// <summary>19         /// 寬20         /// </summary>21         int Height22         {23             get;24             set;25         }26         /// <summary>27         /// 計(jì)算矩形面積28         /// </summary>29         int Area();30     }31     class Program : ImyInterface//繼承自接口32     {33         int width = 0;34         int height = 0;35         /// <summary>36         /// 長(zhǎng)37         /// </summary>38         public int Width39         {40             get41             {42                 return width;43             }44             set45             {46                 width = value;47             }48         }49         /// <summary>50         /// 寬51         /// </summary>52         public int Height53         {54             get55             {56                 return height;57             }58             set59             {60                 height = value;61             }62         }63         /// <summary>64         /// 計(jì)算矩形面積65         /// </summary>66         public int Area()67         {68             return Width * Height;69         }70         static void Main(string[] args)71         {72             Program program = new Program();//實(shí)例化Program類對(duì)象73             ImyInterface imyinterface = program;//使用派生類對(duì)象實(shí)例化接口ImyInterface74             imyinterface.Width = 5;//為派生類中的Width屬性賦值75             imyinterface.Height = 3;//為派生類中的Height屬性賦值76             Console.WriteLine("矩形的面積為：" + imyinterface.Area());77         }78     }79 }

 本題的關(guān)鍵出錯(cuò)點(diǎn)是：在接口里聲明方法的時(shí)候的形式要與接口的實(shí)現(xiàn)里面方法的定義形式保持一致，否則會(huì)出現(xiàn)錯(cuò)誤：“

錯(cuò)誤 1 “Area”方法沒(méi)有任何重載采用“2”個(gè)參數(shù)”