本教程演示如何显式实现接口成员以及如何从接口例子访问这些成员
=dtH2>教程实现接口
类可以显式实现该接口成员当显式实现某成员时
不能通过类例子访问该成员而只能通过该接口例子访问该成员本教程包含两个举例第
个举例阐释如何显式实现和访问接口成员第 2个举例展示如何实现具有相同成员名两个接口=dtH4>举例 1本举例声明
个 // explicit1.cs
erface IDimensions { float Length
; float Width;}
Box : IDimensions { float lengthInches; float widthInches; public Box(float length, float width) { lengthInches = length; widthInches = width; } // Explicit erface member implementation: float IDimensions.Length { 
lengthInches; } // Explicit erface member implementation: float IDimensions.Width { widthInches; } public 
void Main { // Declare a instance \"myBox\": Box myBox = 
Box(30.0f, 20.0f); // Declare an erface instance \"myDimensions\": IDimensions myDimensions = (IDimensions) myBox; // Pr out the dimensions of the box: /* The following commented lines would produce compilation errors because they try to access an explicitly implemented erface member from a instance: */ //
.Console.WriteLine(\"Length: {0}\", myBox.Length); //.Console.WriteLine(\"Width: {0}\", myBox.Width); /* Pr out the dimensions of the box by calling the methods from an instance of the erface: */ .Console.WriteLine(\"Length: {0}\", myDimensions.Length); .Console.WriteLine(\"Width: {0}\", myDimensions.Width); }}=dtH4>输出Length: 30Width: 20
=dtH4>代码讨论
- 请注意 Main 思路方法中下列代码行被注释掉
它们将产生编译
显式实现接口成员不能从类例子访问: //.Console.WriteLine(\"Length: {0}\", myBox.Length);//.Console.WriteLine(\"Width: {0}\", myBox.Width); - 还请注意Main 思路方法中下列代码行成功输出框尺寸这些思路方法是从接口例子
: .Console.WriteLine(\"Length: {0}\", myDimensions.Length);.Console.WriteLine(\"Width: {0}\", myDimensions.Width);
员继承共享相同成员名两个接口并为每个接口成员提供个单独实现本举例同时以公制单位和英制单位显示框尺寸接口有相同
成员名 // explicit2.cs// Declare the English units
erface:erface IEnglishDimensions { float Length; float Width;}// Declare the metric units erface:erface IMetricDimensions { float Length; float Width;}// Declare the \"Box\" that implements the two erfaces:// IEnglishDimensions and IMetricDimensions: Box : IEnglishDimensions, IMetricDimensions { float lengthInches; float widthInches; public Box(float length, float width) { lengthInches = length; widthInches = width; }// Explicitly implement the members of IEnglishDimensions: float IEnglishDimensions.Length { lengthInches; } float IEnglishDimensions.Width { widthInches; }// Explicitly implement the members of IMetricDimensions: float IMetricDimensions.Length { lengthInches * 2.54f; } float IMetricDimensions.Width { widthInches * 2.54f; } public void Main { // Declare a instance \"myBox\": Box myBox = Box(30.0f, 20.0f); // Declare an instance of the English units erface: IEnglishDimensions eDimensions = (IEnglishDimensions) myBox; // Declare an instance of the metric units erface: IMetricDimensions mDimensions = (IMetricDimensions) myBox; // Pr dimensions in English units: .Console.WriteLine(\"Length(in): {0}\", eDimensions.Length); .Console.WriteLine(\"Width (in): {0}\", eDimensions.Width); // Pr dimensions in metric units: .Console.WriteLine(\"Length(cm): {0}\", mDimensions.Length); .Console.WriteLine(\"Width (cm): {0}\", mDimensions.Width); }}=dtH4>输出Length(in): 30Width (in): 20Length(cm): 76.2Width (cm): 50.8
=dtH4>代码讨论如果希望默认度量采用英制单位
请正常实现 // Normal implementation:public float Length
{ lengthInches;}public float Width{ widthInches;}// Explicit implementation:float IMetricDimensions.Length { lengthInches * 2.54f;}float IMetricDimensions.Width { widthInches * 2.54f;}这种情况下
可以从类例子访问英制单位而从接口例子访问公制单位:.Console.WriteLine(\"Length(in): {0}\", myBox.Length);.Console.WriteLine(\"Width (in): {0}\", myBox.Width); .Console.WriteLine(\"Length(cm): {0}\", mDimensions.Length);.Console.WriteLine(\"Width (cm): {0}\", mDimensions.Width);
最新评论