10-1.cs

java基础方面的一些实例代码

//10-1
using System;
class A
{   
	public void Func() { Console.WriteLine("Func() in A"); }
	public virtual void VO() { Console.WriteLine("BaseClass.VO()"); }
}
class B:A
{
	public int j;
	new public  void Func() { j=2; Console.WriteLine("Func() in B,  the new member = "+j); }
	public override void VO() { j=2; Console.WriteLine("VO() in B, the new member = "+j);  }
	public void FromBase(){ base.VO();}
}
class C:B
{
	public int k;
	new public  void Func() { k=3; Console.WriteLine("Func() in C, the new member = "+k); }
	public override void VO() {k=3; Console.WriteLine("VO() in C, the new member = "+k); }
}
class D:C
{
	public int m;
	new public  void Func() { m=4; Console.WriteLine("Func() in D, the new member = "+m); }
	new public virtual void VO() { m=4; Console.WriteLine("VO() in D, the new member = "+m);}
}
class E:D
{
	public int n;
	new public  void Func() { n=5; Console.WriteLine("Func() in E, the new member = "+n); }
	public override void VO() { n=5; Console.WriteLine("VO() in E, the new member = "+n);}
}
class Test
{
	static public void VirtualandOverride(A a)
	{
		a.Func();
		a.VO();
	}
	static void Main() 
	{
		A aa= new A();     //基类对象aa
		A ab = new B();    //或者A ab = bb;  基类对象，引用指向派生类对象
		B bb = new B();    //派生类对象bb
		ab.Func();		   //调用非虚方法，输出：“Func() in A”
		bb.Func();		   //调用非虚方法，输出：“Func() in B, the new member = 2”
		aa.VO();		   //输出：“BaseClass.VO()”
		//Console.WriteLine(ab.j);		//错误:A中并不包含对j的定义
		ab.VO();		   //调用虚方法，输出：“VO() in B, the new member = 2”。ab中没有j，但却通过覆盖的方法使用了j
		bb.VO();		   //调用虚方法，输出：“VO() in B, the new member = 2”
		bb.FromBase();		   //输出：“BaseClass.VO()”,表明虽然覆盖了基类的VO()，但是基类的VO()仍然存在
		Console.WriteLine(ab.ToString());//输出：“B”，ab的类型是B?
		//B ba=ab;        //错误： 无法将类型“A”隐式转换为“B”，ab到底是不是B类型？
		Console.WriteLine("Testing");
		VirtualandOverride(aa); // Func() in A // BaseClass.VO()
		VirtualandOverride(ab); // Func() in A // VO() in B, the new member = 2
		A ac =new C();          
		VirtualandOverride(ac);	// Func() in A // VO() in C, the new member = 3	
		A ad =new D();
		VirtualandOverride(ad); // Func() in A // VO() in C, the new member = 3
		A ae=new E();
		VirtualandOverride(ae); // Func() in A // VO() in C, the new member = 3
	}
}