完成示例的方法 TestCars3 和 TestCars4。这些方法直接调用 ShowDetails，首先从宣布具有类型 ConvertibleCar 和 Minivan (TestCars3) 的对象调用，然后从具有类型 Car (TestCars4) 的对象调用。以下代码定义了这两种方法。
public static void TestCars3()
{
System.Console.WriteLine("nTestCars3");
System.Console.WriteLine("----------");
ConvertibleCar car2 = new ConvertibleCar();
Minivan car3 = new Minivan();
car2.ShowDetails();
car3.ShowDetails();
}
public static void TestCars4()
{
System.Console.WriteLine("nTestCars4");
System.Console.WriteLine("----------");
Car car2 = new ConvertibleCar();
Car car3 = new Minivan();
car2.ShowDetails();
car3.ShowDetails();
}
该方法产生下面的输出，它对应本主题中第一个示例的结果。
// TestCars3
// ----------
// A roof that opens up.
// Carries seven people.
// TestCars4
// ----------
// Standard transportation.
// Carries seven people.
以下代码显示了整个项目及其输出。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace OverrideAndNew2
{
class Program
{
static void Main(string[] args)
{
// Declare objects of the derived classes and test which version
// of ShowDetails is run, base or derived.
TestCars1();
// Declare objects of the base class, instantiated with the
// derived classes, and repeat the tests.
TestCars2();
// Declare objects of the derived classes and call ShowDetails
// directly.
TestCars3();
// Declare objects of the base class, instantiated with the
// derived classes, and repeat the tests.
TestCars4();
}
public static void TestCars1()
{
System.Console.WriteLine("nTestCars1");
System.Console.WriteLine("----------");
Car car1 = new Car();
car1.DescribeCar();
System.Console.WriteLine("----------");
// Notice the output from this test case. The new modifier is
// used in the definition of ShowDetails in the ConvertibleCar
// class.
ConvertibleCar car2 = new ConvertibleCar();
car2.DescribeCar();
System.Console.WriteLine("----------");
Minivan car3 = new Minivan();
car3.DescribeCar();
System.Console.WriteLine("----------");
}
输出:
TestCars1
----------
Four wheels and an engine.
Standard transportation.
----------
Four wheels and an engine.
Standard transportation.
----------
Four wheels and an engine.
Carries seven people.
----------
