接口概念是从哪里来的?

public class Dog : Animal, IMammal

public class Dog extends Animal implements IMammal

Email from Patrick Naughton

http://en.wikipedia.org/wiki/Virtual_function

static string Method(int i)

class IFoo
{
public:
  void Bar() =0;
  void Bar2() =0;
};

class Concrete : public IFoo
{
public:
  void Bar() { ... }
  void Bar2() { ... }
}

class IExecutable
{
public:
    virtual void Execute() = 0;
};

class MyClass : public IExecutable
{
public:
    void Execute() { return; };
};

public interface IPurring
{
    void Purr();
}

public class Cat : Animal, IPurring
{
    public Cat(bool _isAlive)
    {
        isAlive = _isAlive;
    }

    #region IPurring Members

    public void Purr()
    {
        //implement purring
    }

    #endregion
}

http://java.sun.com/docs/books/tutorial/java/concepts/interface.html