接口被定义为一个语法合约,继承接口的所有类都应该遵循.界面定义了语法契约的'what'部分,派生类定义了语法契约的'how'部分.
接口定义属性,方法和事件,它们是接口的成员.接口仅包含成员的声明.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.
抽象类在某种程度上起到相同的作用,但是,它们主要用于仅宣布少数方法的情况由基类和派生类实现功能.
声明接口
使用interface关键字声明接口.它类似于类声明.接口语句默认是公共的.以下是接口声明的示例 :
public interface ITransactions { // interface members void showTransaction(); double getAmount();}
示例
以下示例演示了上述接口的实现 :
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时,会产生以下结果 :
Transaction: 001Date: 8/10/2012Amount: 78900Transaction: 002Date: 9/10/2012Amount: 451900