c# 中 method new 和 overide 的差异

new使用

using System;

public class BaseClass
{
    public void ShowMessage()
    {
        Console.WriteLine("Message from BaseClass");
    }
}

public class DerivedClass : BaseClass
{
    // 使用 new 隐藏基类中的 ShowMessage 方法
    public new void ShowMessage()
    {
        Console.WriteLine("Message from DerivedClass");
    }
}

public class Program
{
    public static void Main()
    {
        BaseClass baseObj = new BaseClass();
        baseObj.ShowMessage();  // 输出：Message from BaseClass
        
        DerivedClass derivedObj = new DerivedClass();
        derivedObj.ShowMessage();  // 输出：Message from DerivedClass
        
        BaseClass baseRef = new DerivedClass();
        baseRef.ShowMessage();  // 输出：Message from BaseClass（基类方法被调用，因为它使用基类引用）
    }
}

overide使用

using System;

public class BaseClass
{
    public virtual void ShowMessage()
    {
        Console.WriteLine("Message from BaseClass");
    }
}

public class DerivedClass : BaseClass
{
    // 使用 override 重写基类的 ShowMessage 方法
    public override void ShowMessage()
    {
        Console.WriteLine("Message from DerivedClass");
    }
}

public class Program
{
    public static void Main()
    {
        BaseClass baseObj = new BaseClass();
        baseObj.ShowMessage();  // 输出：Message from BaseClass
        
        DerivedClass derivedObj = new DerivedClass();
        derivedObj.ShowMessage();  // 输出：Message from DerivedClass
        
        BaseClass baseRef = new DerivedClass();
        baseRef.ShowMessage();  // 输出：Message from DerivedClass（调用派生类的方法）
    }
}