抽象类那点事（一步步案例分析，为什么需要它）

当你想规定好一些标准,让后面开发人员去按照这些标准去做的时候,你会去抽象;当有些方法你觉得现在实现不太合适,你会选择抽像它,等接下来的开发人员去实现;当你觉得有些方法觉得现在实现了或者以后开发还可以更改,你会选择virtual它 .

 来源于：http://www.cnblogs.com/IAmBetter/archive/2011/12/21/2296196.html

抽象类abstract抽象方法的类要声明为抽象类构造函数和静态方法不能声明为抽象多态性是一个虚方法，可以重写这个方法，实现同一个方法不同的表现形式对于抽象方法的重写，是说的对于这个方法的派生类的实现。对于抽象类和接口的方法都需要实现。抽象方法是无法写方法体的抽象类可以写 实现的方法接口不可以写 实现的方法案例1：

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace ConsoleApplication2{public abstract class Employee//雇员抽象类 {public string FirstName { get; private set; }public string LastName { get; private set; }public string Ssn { get; private set; }public Employee(string first, string last, string ssn) { FirstName = first; LastName = last; Ssn = ssn; }public abstract decimal Earning();public virtual int Time(int times)//抽象类可以写虚方法 {return times; }public override string ToString() {return string.Format("FirstName:{0} LastName:{1} SSN:{2}", FirstName, LastName, Ssn); } }public class SalariedEmployee : Employee//薪水雇员类 {private decimal weeksalay;public SalariedEmployee(string first, string last, string ssn, decimal salay) : base(first, last, ssn)//调用抽象类的构造函数 { Weeksalay = salay; }public decimal Weeksalay {get { return weeksalay; }set { weeksalay = (value > 0) ? value : 0; } }public override decimal Earning() { Weeksalay = Weeksalay* 7;return Weeksalay; }public override string ToString()//如果不重写ToString方法那么继承的是抽象类的方法 {return string.Format("{0} Weeksalay:{1}",base.ToString(), Weeksalay); } }class HourEmployee : Employee//小时工类 {private decimal wage;private int hour;public HourEmployee(string first, string last, string ssn, decimal hourwage, int hourtime) : base(first, last, ssn) { Hour = hourtime;//注意这里，2个属性的前后顺序会决定了结果的 Wage = hourwage; }public decimal Wage {get { return wage; }set { wage = (value > 0) ? value : 0; } }public int Hour {get { return hour; }set { hour = (value > 0) ? value : 0; } }public override decimal Earning() {if (Hour <= 40) { Wage = Wage* Hour; }else { Wage = Wage* 40 + (Hour - 40) * Wage* 1.5m; }return Wage; }public override string ToString() {return string.Format("{0} Hourwage:{1} Hourtimes:{2},Wage:{3}", base.ToString(), Wage, Hour, Wage);//这里继承抽象类的ToString方法 } }class BaseHe_Employee : HourEmployee//间接继承抽象类 {private decimal rate;private decimal salay;public BaseHe_Employee(string first, string last, string ssn, decimal hourwage, int hourtime, decimal rate, decimal salay) : base(first, last, ssn, hourwage, hourtime) { Rate = rate; Salay = salay; }public decimal Rate {get { return rate; }set { rate = (value > 0) ? value : 0; } }public decimal Salay {get { return salay; }set { salay = (value > 0) ? value : 0; } }public override decimal Earning() {return Salay+ base.Earning(); }public override string ToString() {return string.Format("{0} Rate:{1},Salay:{2}", base.ToString(), Rate, Salay);//这里继承抽象类的ToString方法 } }class Test {static void Main() {//SalariedEmployee oneSE = new SalariedEmployee("Mr.w", "Mery An", "10086", 6500.00m);//Console.WriteLine(oneSE.ToString()); BaseHe_Employee oneBHE = new BaseHe_Employee("Mr.w", "Mery An", "10086", 6.50m, 24, 15.5m, 16.5m); Console.WriteLine(oneBHE.ToString()); Console.WriteLine(oneBHE.Earning());//HourEmployee oneHE = new HourEmployee("Mr.w", "Mery An", "10086", 6.50m, 24);//Console.WriteLine(oneHE.ToString());//Console.WriteLine(oneHE.Earning()); } }}

转载于:https://www.cnblogs.com/lyl2001431/archive/2011/12/22/2297211.html

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