one question.. [ inheritance ]

[TheNewOne]

Hello, this is my first posting here but I have been a long time reader of this forum (Turing index). I have two questions that boggle my mind.
I've searched on the internet but it's pretty hard to understand everything they say because i don't know alot of the terminology they use. I apparently have a simplistic mind.

The question:
I understnad that inheritance is a very important concept in programming, what is it actually? What is it in terms of class, superclass, and objects? Also what is overriding?

Many thanks!

[wtd]

A class may inherit from a superclass. The inherited class gains access to all public and protected aspects of the parent class. Inheritance defines an is-a relationship between classes. A child class may override anything it inherits from the parent class.

We start out with a very basic Dog class.

code:

class Dog {    private String name;    public Dog(String initName) {       name = initName;    }    public String bark() {       return "Woof!";    } }

Now, we want a GuardDog class. We've already got a Dog class, so why reinvent the whole thing? Besides, a guard dog is a dog...

Assume a Person class.

code:

class GuardDog extends Dog {    // create a constructor for this class    public GuardDog(String initName) {       // just call the parent class' constructor       super(initName);    }    public void attack(Person intruder) {       System.out.println(bark());       person.reduceHealth();    } }

And now, to demonstrate overriding, we create a sad MuteGuardDog class. To do this we override "bark()" so that it returns an empty string.

code:

class MuteGuardDog extends GuardDog {    public MuteGuardDog(String initName) {       super(initName);    }    public String bark() {       return "";    } }

And to sum up... MuteGuardDog is a GuardDog is a Dog. This of course also means that a MuteGuardDog is a Dog.

Anywhere your program would require a Dog you could use a child of the Dog class.

[TheNewOne]

Great! I have understood alot. Thank you very much.