Abstract class

What is an abstract class?
Why do we do implements at times and extends at times when writing java servlets?

What is the difference between these 2?
Why do we do
public interface ....
and
public class ...

What does interface and class stand for here?

Whoa dude...you need to read up on some JAVA BASICS. An abstract class in
defined like this:

public abstract class MyClass{ }

It is just like any other class EXCEPT that you can't create objects from
abstract classes. You can only create objects of it's subclasses which 'extend'
an abstract class. WHY, have abstract classes? Well, it is used to FORCE
the programmers that want to use the abstract class to use certain methods
in the subclasses that wanna extend an abstract class. These methods are
defined like so, which are inthe abstract class:

public abstract void myAbstractMethod();

Just like that...looks strange does it? Where's the { blah; blah; code to
use in this method?;} (IE it is missing the curly braces) Hehehe well an
abastract method is NOT used in the abstract class, they are used and DEFINED
in the subclasses that inheriate them. The subclasses HAVE TO empliment
ALL abstract methods of an abstract class or you will get a compile error.
Hence, FORCING a certain code structure. Abstract methods MUST be public
since all abstract methods in an abstract class that a SUBclass extends MUST
be implemented, or an error happends.

implements keyword is related to interfaces. An interface is kinda like
a very EXTREME abstract class and is defined like so:

public interface MyCrap(){}

interface is a CLASS but, no class keyword is used. An interface is like
an abstract class, except an interface can ONLY have abstract methods. An
abstract Class can have BOTH regular methods AND abstract methods. You,
cant instantiate an interface. YOu have to create subclasses (ie implement)
or (same thing as extend but they decided to make it clear you where extending
an interface so they called it implements) You like in an abstarct class
MUST implement ALL the methods in an interface. There fore all methods are
abstract by default. Think of it as a working template and these parts MUST
be used in order for a certain operation to work.

"Manika" <manika@mailexcite.com> wrote:
>
>What is an abstract class?
>Why do we do implements at times and extends at times when writing java
servlets?
>
>What is the difference between these 2?
>Why do we do
>public interface ....
>and
>public class ...
>
>What does interface and class stand for here?
>