[Tutor] impact of OO

[Danny Yoo]

> But everywhere I used to read about programming would talk about how OO
> had revolutionized programming.  Now that I know what it is, although I
> really appreciate it and will use it whenever I can (it's so... clean
> compared to what I was doing before), but I still don't really see how
> it's that big a deal -- it's simply a different way of organizing code,
> as far as I can tell.

Yes.  *grin*

Actually, it's not a unified opinion that OOP is the best thing since
sliced bread.  Paul Graham has some good reasons why it might not be
revolutionary on his web site:

    http://www.paulgraham.com/noop.html
    http://www.paulgraham.com/reesoo.html



> PS:  Also, I have heard someone say that "in Java everything is an
> object".  What does this mean?

They may be referring to the idea that all Java classes inherit from a
single base class called "Object".  Everything in Java (functions,
variables, etc.) needs to be in a class, and in that sense, Java's classes
act sorta like Python's modules... except Java classes are very strict.


I'm not sure it's perfectly true that everything is an Object in Java:
there are primitive values in Java, like 'int' or 'float', that just don't
like being treated as objects:

//////
ArrayList l = new ArrayList(); // An "ArrayList" in java is similar to
                               // Python's list.

v.add(42);                     // But this won't work.  42 is an integer,
                               // a primitive type, and primitive types
                               // aren't a subclass of Object.

v.add(new Integer(42));        // Java uses a class "wrapper" to get
                               // around this situation.
//////

So there's a great divide between primitive types and Objects in Java.


> I think I am interested in learning Java, especially since there are
> many employers in my area (Boston)  advertising an interest in Java
> programmers (and I will be out of a job as soon as my project is
> finished).  Sadly, much more than Python or PHP.  But it seems like a
> big language to learn.

You might be interested in the Jython project:

    http://jython.org/

You can leverage what you're learning in Python directly toward Java:
Jython allows you to write Java classes in Python.


Good luck!