Java Vs C#继承实现多态

java vs c#，继承实现多态

java vs c#，继承实现多态

java 和 c# 对于继承时，多态的实现有很大的差异。

下边的例子，同样的代码:

c# print: animal;
java print: dog

想要 c# 输出 dog，需要修改代码为 demo3.

父类方法添加 virtual, 子类方法添加 override

参考： https://stackoverflow.com/questions/13323099/java-inheritance-vs-c-sharp-inheritance

In java all of methods are virtual by default. And methods in derived classes override methods from base. In C# they are not.
Declare this method with virtual keyword in base class and with override in derived.

java 默认方法都是 virtual，子类里相同签名的方法都是 override。在 java 里用继承来实现多态的限制少

c# 里对用继承来实现多态的限制多，需要同时修改父类和子类

//  demo1, c#
public class Test
{
    public static void Main(string[] args)
    {
        Animal animal = new Dog();
        animal.Print();
        //out: animal
    }
}
class Animal
{
    public void Print()
    {
        Console.WriteLine("animal");
    }
}
class Dog : Animal
{
    public void Print()
    {
        Console.WriteLine("dog");
    }
}

// demo2, java
public class InheritanceDemo {
    public static void main(String[] args) {
        Animal animal = new Dog();
        animal.print();
        // out: dog
    }
}
class Animal {
    public void print() {
        System.out.println("animal");
    }
}
class Dog extends Animal {
    public void print() {
        System.out.println("dog");
    }
}

// demo3, c#
public class Test2
{
    public static void Main(string[] args)
    {
        Animal2 animal2 = new Dog2();
        animal2.Print();
        // out: dog
    }
}

class Animal2
{
    // add virtual
    public virtual void Print()
    {
        Console.WriteLine("animal");
    }
}

class Dog2 : Animal2
{
    // add override
    public override void Print()
    {
        Console.WriteLine("dog");
    }
}

java vs c#， 继承实现多态

java vs c#，继承实现多态