Csharp 简明教程

C

接口被定义为一个语法契约，所有继承该接口的类都应遵守。接口定义语法契约的 'what' 部分，而派生类定义语法契约的 'how' 部分。

An interface is defined as a syntactical contract that all the classes inheriting the interface should follow. The interface defines the 'what' part of the syntactical contract and the deriving classes define the 'how' part of the syntactical contract.

接口定义了属性、方法和事件，它们是接口的成员。接口仅包含成员的声明。由派生类负责定义成员。它通常有助于提供派生类将遵循的标准结构。

Interfaces define properties, methods, and events, which are the members of the interface. Interfaces contain only the declaration of the members. It is the responsibility of the deriving class to define the members. It often helps in providing a standard structure that the deriving classes would follow.

抽象类在一定程度上具有相同用途，但当基类仅需声明少数方法且派生类实现功能时，则它们通常被使用。

Abstract classes to some extent serve the same purpose, however, they are mostly used when only few methods are to be declared by the base class and the deriving class implements the functionalities.

Declaring Interfaces

使用 interface 关键字声明接口。它类似于类声明。默认情况下，interface 语句是公共的。以下是一个接口声明示例 -

Interfaces are declared using the interface keyword. It is similar to class declaration. Interface statements are public by default. Following is an example of an interface declaration −

public interface ITransactions {
   // interface members
   void showTransaction();
   double getAmount();
}

Example

以下示例演示如何实现上述接口 -

The following example demonstrates implementation of the above interface −

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System;

namespace InterfaceApplication {

   public interface ITransactions {
      // interface members
      void showTransaction();
      double getAmount();
   }
   public class Transaction : ITransactions {
      private string tCode;
      private string date;
      private double amount;

      public Transaction() {
         tCode = " ";
         date = " ";
         amount = 0.0;
      }
      public Transaction(string c, string d, double a) {
         tCode = c;
         date = d;
         amount = a;
      }
      public double getAmount() {
         return amount;
      }
      public void showTransaction() {
         Console.WriteLine("Transaction: {0}", tCode);
         Console.WriteLine("Date: {0}", date);
         Console.WriteLine("Amount: {0}", getAmount());
      }
   }
   class Tester {

      static void Main(string[] args) {
         Transaction t1 = new Transaction("001", "8/10/2012", 78900.00);
         Transaction t2 = new Transaction("002", "9/10/2012", 451900.00);

         t1.showTransaction();
         t2.showTransaction();
         Console.ReadKey();
      }
   }
}

编译并执行上述代码后，将产生以下结果 −

When the above code is compiled and executed, it produces the following result −

Transaction: 001
Date: 8/10/2012
Amount: 78900
Transaction: 002
Date: 9/10/2012
Amount: 451900