Basic Doubt

>1.why don't we have pointers in java .Whatz itz advantage.

Java has no pointers but instead uses references. A reference provides access only to the functionality of the object. The programmer does not have direct access to memory removing the dangers of pointer manipulation. For example:

* Pointers remove the concept of private data since they can provide direct access to that data.

* In some cases, integer values can be converted to pointer addresses which can result in incorrect addresses being formed and hence memory corruption.

* Arrays can be directly accessed by pointers. This can result in the program writing past the end of the array.

Interestingly, the lack of pointers can be a hindrance in specific cases. For example, imagine trying to create a memory manager for an operating system without pointers.

> 2.Whatz the difference between virtual function in c++ and interface in java.

C++ - A virtual function is a function member of a class, declared using the "virtual" keyword. A pointer to a derived class object may be assigned to a base class pointer, and a virtual function called through the pointer. If the function is virtual and occurs both in the base class and in derived classes, then the right function will be picked up based on what the base class pointer "really" points at.

Java Interface - an abstract base class with all pure virtual functions and no instance variables.

Hope this helps...

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HydieBuddy

hydiebuddya at 2007-7-16 20:35:49 >

Please help spread the word: The word "doubt" is inappropriate and confusing for subject lines. I have no idea what you mean by "doubt." Did you mean "confusion"? Even "confusion," though, is too vague. The more meaningful & specific your subject, the more meaningful & specific the replies will be.

Dick_Adamsa at 2007-7-16 20:35:50 >

The major advantage of not having pointers is that you can't have pointers which look valid but in fact point to never never land. Invalid pointers have been the cause of endless grief to many C/C++ programmers (myself being one).

In Java, the only invalid reference is null, and you can immediately tell it's invalid. You can't have any "silent" errors with a null reference - the NullPointerException will hit you like a ton of bricks. This is not the case in C: A program can seem to execute normally when it is actually reading from or writing to the wrong place in memory.

Dick_Adamsa at 2007-7-16 20:35:50 >