所谓多态

今天无意间看到了一篇文章，感觉很棒，贴在这儿。突然意识到，所谓多态，就是一个类的多种形态，如果撒尿也算的话哈哈哈

地址：http://stackoverflow.com/questions/154577/polymorphism-vs-overriding-vs-overloading

 

The clearest way to express polymorphism is via an abstract base class (or interface)

public abstract class Human{
   ...
   public abstract void goPee();
}

 

This class is abstract because the goPee() method is not definable for Humans. It is only definable for the subclasses Male and Female. Also, Human is an abstract concept — You cannot create a human that is neither Male nor Female. It’s got to be one or the other.

So we defer the implementation by using the abstract class.

public class Male extends Human{
...
    @Override
    public void goPee(){
        System.out.println("Stand Up");
    }
}

 

and

public class Female extends Human{
...
    @Override
    public void goPee(){
        System.out.println("Sit Down");
    }
}

 

Now we can tell an entire room full of Humans to go pee.

public static void main(String args){
    ArrayList<Human> group = new ArrayList<Human>();
    group.add(new Male());
    group.add(new Female());
    // ... add more...

    // tell the class to take a pee break
    for (Human person : group) person.goPee();
}

 

Running this would yield:

Stand Up
Sit Down
...