Re: Wrapper classes are Immutable but you use them to make a function parameter a reference?
<marcwentink@hotmail.com> wrote in message
news:1164870635.877598.162100@n67g2000cwd.googlegroups.com...
Mijn goede vriend Chris Uppal schreef deze boodschap als constructief
advies:
(And the above is Dutch for: 'My dear friend Chris Uppal wrote this
message as constructive advice.')
Pardon my jumping in here... The title caught my eye...
I am studying some java. My main language I am used to program in is
C++. Doing some test questions I am confused. It seems Wrapper classes
for primitives are Immutable classes, so their value cannot be changed.
Correct.
Uhm, that mean the value of the integer cannot be changed, right? It
does not mean the reference to Wrapper class cannot be changed. I am
like 90% sure about this, but just to check it.
That isn't the purpose of the wrapper classes.
Then what is, since I think making a integer immutable could be done by
using a final variable?
The wrappers are for situations that require a full featured
java.lang.Object instead of a primitive, such as hash maps, or having a
monitor to synchronize on, or has several standard object methods, such as
equals(Object other) or toString(), or in the case of numbers, extends
Number, with all of the Number base methods.
Using them to simulate C++ parameter passing semantics is not one of
the valid uses.
Do I understand that you think passing parameters by reference is a bad
concept in itself?
Not in C++, but it is not an idiom in Java, so experienced Java programmers
would want to know what you were smoking -- unless there was an
intrinsically good design reason to use it. Most of the time, I see this
kind of "language abuse" in programs (stupidly) ported from C++ instead of
re-written to take advantage of Java features and idioms.
Thanks a lot for the information, and I need to read a lot more about
Java still.
Marc Wentink