abstract :表示方法是抽象方法,在子类中必须重写。抽象方法所在的类必须是抽象类,即用abstract modifiers;
virtual:表示此方法是virtual方法,除了在子类中可以重写外(在子类中也可直接使用),和普通方法完全一样;
override:表示重写父类的virtual方法;
new: 显式隐藏从基类继承的成员;
区别:
virtual:标记方法为虚方法
1.可在派生类中以override覆盖此方法
2.不覆盖也可由对象调用
3.无此标记的方法(也无其他标记),重写时需用new隐藏原方法
abstract 与virtual : 方法重写时都使用 override 关键字
Eg1:
public abstract class Book
{
public Book()
{
}
public abstract void getPrice(); //抽象方法,不含主体
public virtual void getName() //虚方法,可覆盖
{
Console.WriteLine("this is a test:virtual getName()");
}
public virtual void getContent() //虚方法,可覆盖
{
Console.WriteLine("this is a test:virtual getContent()");
}
public void getDate() //一般方法,若在派生类中重写,须使用new关键字
{
Console.WriteLine("this is a test: void getDate()");
}
}
public class ChineseBook : Book
{
public override void getPrice() //实现抽象方法,必须实现
{
Console.WriteLine("this is a test:ChineseBook override abstract getPrice()");
}
public override void getName() //覆盖原方法,不是必须的
{
Console.WriteLine("this is a test:ChineseBook override virtual getName()");
}
public new void getDate() {
Console.WriteLine("this is a test:ChineseBook new getDate()");
}
public void
Output:
this is a test:ChineseBook override abstract getPrice()
this is a test:ChineseBook override virtual getName()
this is a test:virtual getContent()
this is a test:ChineseBook new getDate()
Eg2:
public abstract class FlowModel
{
public abstract void A();
public virtual void B(){
Console.WriteLine("Orginal B()");
}
public virtual void C(){
Console.WriteLine("Orginal C()");
}
public void D(){
Console.WriteLine("Orginal D()");
}
}
public class Flow:FlowModel
{
public override void A()
{
//执行步骤A
Console.WriteLine("Execute Step A ");
}
public virtual void B()
{
//执行步骤B
Console.WriteLine("Execute Step B");
}
public void C()
{
//执行步骤C
Console.WriteLine("Execute Step C");
}
public new void D() {
Console.WriteLine("Execute Step D");
}
public void Run()
{
A();
B(); //步骤B是扩展点 ,可以由子类决定具体执行什么
C();
D();
}
}
Output:
Execute Step A
Execute Step B
Execute Step C
Execute Step D