C++ OOP and JAVA OOP

MDMA · 04-04-2005 10:52AM #1

hello all... well this is my problem i have been doing c++ for 1.5 years and have started java about a month ago..now i have a good/strong understanding of oop a a concept but i have been having a problem joining the concept to the two languages for example in c++ i understand how a class is defined and initated but in java it seems a class can RETURN a value for example
public string blah(){

return stringans
} is a class that returns a string..
how is this possible where dose the class go and what data type is the returned value is it a string or a blah class...how is this Class that returns a value implemented in c++ and what is the benifit + dose this not make java a oop/procedureal language because in my mind a class that returns a value without calling 1 of its methods is more like a function..
this to me seems to break the logic... i have a good feeling the returned value is a String but again this makes the class blah more like a function....i would love to see a bit of code with a class in c++ that returns a value and some sort of example as to why this is a good oop idea..thanks in advance

lynchie · 04-04-2005 11:21AM

public String blah(){..} is a method (function in c talk). It is not a class but a method within a class. A class in Java is defined as public class Blah{...}

MDMA · 04-04-2005 11:30AM

so ur saying that oop in java still uses functions ah ...that dose make sense...i do intend on reading a good mamoth of a book on all this java oop but as for now i want to see how far i go without forking out for a book...+ i can t read online so thinking in java is no good b4 u reply suggesting it ..sorry just cant read off the comp screen...anyway yes that dose help a little but just to clarify

public class blah(){
} is a class which must have 1 main "method"

public void static main(String[] args){
}//ah so this is a method not a class ah is see.good stuff

thanks

rsynnott · 04-04-2005 12:17PM

No need for a book, Java OO is easy if you already know C++ OO.

Classes should be defined in .java files of the same name, case sensitive. You'll get away with case-insensitivity on Windows, but you'd be in trouble if you ever wanted to compile on a UNIX.

All methods are defined WITHIN classes, eg:
public class Thing{
Thing(){
/* Do Stuff */
}
}

Only classes which are actually executable need a main function.

The main function is static; it's often useful to create an instance of the main class within the main function, and transfer control to that.

There's no operator overloading or multiple inheritance. An effect similar to multiple inheritance can be achieved by using interfaces:
Interface ThingInterface{
public String Something();
}
Interfaces just contain prototypes, and a class can implement unlimited interfaces:
public class AThing extends Thing implements ThingInterface, ThingInterface2{....

Everything is pass-by-reference except basic data types (boolean,int,float,double, etc.)

Those are the big differences I can think of offhand.

MDMA · 04-04-2005 12:52PM

Ah good stuff that clears up a few things..I know the java oop is easy enough but then im a newbie ha ha.. well onward's it is so got to learn lots of java....

thanks again
Scott McNealy
CEO, HOT_Sun Microsystem, Inc ha ha

C++ OOP and JAVA OOP

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