Re: The Java no pointer big fat lie!

• Previous message: Juha Laiho: "Re: Java Object-Oriented Prgramming- Basics for High School Course ???"
• In reply to: axter: "The Java no pointer big fat lie!"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Date: Sun, 27 Feb 2005 00:35:50 -0800

So what's your point?

Does Java have auto variables that construct and destruct by scope? No.

Does it have inline/netsted object storage? No.

Are object references a native memory pointer or an abstracted
reference? Depends on the JVM.

It's a different language so comparing the finest details to C++ is
silly.

In article <1109198825.659612.130510@l41g2000cwc.googlegroups.com>,
 "axter" <temp@axter.com> wrote:

> Whenever I read a Java book and it states that Java has no pointers, it
> makes my teeth grind. It would be more accurate to say Java only uses
> pointers.
>
> That's right. Java only uses pointers.
> However, that also wouldn't be entirely accurate either, but it would
> be closer to the truth then to say Java doesn't use pointers.
>
> When these books make these claims they're usually explicitly or
> implicitly comparing the Java memory addressing method to the C/C++
> memory addressing methods.
>
> C++ has three main methods for addressing memory. (concrete, pointer,
> and reference)
> Concrete address
> int x = 10;// x is a concrete variable
>
> Pointer address
> int *px = &x; //px is a pointer variable
>
> Reference address
> int &rx=x; //rx is a reference variable
>
> Most Java books would have you believe that Java's memory method is
> not a pointer method, and that it's memory methods are more like the
> C/C++ concrete method.
> However, if the characteristics of all three methods are examine,
> you'll find that Java's memory method characteristics has more in
> common with the C++ pointers, and have very little in common with the
> concrete method.
>
> In C++, when a concrete variable is declared, its constructor is always
> called
> When a reference variable is declared, a constructor is never called.
> When a pointer variable is declared a constructor is called only if it
> is initialized by pointing to a NEW-operator.
> In this characteristic, Java address modal matches only the pointer
> modal.
>
> In C++, a concrete variable must be initialized to address valid
> memory.
> A reference variable must also be initialized to address valid memory.
> A pointer may be initialized to point to nothing at all, or to point to
> valid memory.
> In this characteristic, Java address modal matches only the pointer
> modal.
>
> In C++, a concrete variable (once initialized) can never change the
> memory it's addressing.
> A reference variable (once initialized) can never change the memory
> it's addressing.
> A pointer can change what it's pointing to at any time.
> In this characteristic, Java address modal matches only the pointer
> modal.
>
> In C++, you cannot assign a concrete variable to new operator.
> A reference variable cannot be directly assigned to a new operator.
> A pointer can be directly assigned to a new operator.
> In this characteristic, Java address modal matches only the pointer
> modal.
>
> In C++, pointer arithmetic cannot be performed on a concrete type.
> Pointer arithmetic cannot be performed on a reference type.
> Pointer arithmetic can of course be performed on a pointer variable.
> This is where Java memory modal and C++ pointers differ. You cannot
> perform pointer arithmetic on a Java address method.
>
> Other then pointer arithmetic, Java's memory modal is very much a C++
> pointer memory modal.
>
> So if a Java book really wanted to be more accurate, it would say:
> "Java only uses pointers, and Java pointers lack the ability to
> perform pointer arithmetic."
>
> OK, frag away!

• Previous message: Juha Laiho: "Re: Java Object-Oriented Prgramming- Basics for High School Course ???"
• In reply to: axter: "The Java no pointer big fat lie!"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]