Hi all!


My question relates to creation of an instanse of a class.

When you create a instance of class the constructor gets a message telling it to create a object of that class. I hope so far so good! Ok to my real question, what happens when i create an array of my class? Shouldn't my constructor get calls equal to n.
i.e
n=6;
MyClass[] c = new MyClass[n];

The thing is that i tried to follow the creation of an array of my class but nothing happens, i have JOptionPane.showMessage(null, i++) that popups when i call the constructor. But nothing happens when i create an array but popups when i create one instanse.

In c++ creating an array of a class will message the constructor to create [x] x instances of the class.

How do i create an array of a my class in Java?

Thanks for any reply

Ok!

Let me redefine my question.

In c++ the statement:

Myclass *c = Myclass[n];

will call the default constructor n times, to initiate data members.

In Java i wrote this statement:

Myclass []c = new Myclass[n];

The default constructor doesn't get called. The array just get null references, some how i understand that array (c) get null reference but i would like to find equivalent statement like the one for c++ i wrote down in the first example for Java.

Please post any thought...

We're with you...

Unfortunately, Java doesn't handle the arrays quite the same, as you noticed.

The initial declaration that you did creates 6 MyClass references, and then a loop is necessary to create a new MyClass object for each element. [Ugh, I know] But of course, Java makes it easy to then set/create objects in a loop:
I haven't found any utility [yet] that helps do both in one step. I did find a fill() function in java.util.Arrays, but unfortunately it assigns the SAME object to the entire array if you try to do:
-- which isn't very helpful either. I haven't looked into the newer 1.5 API to see if there may be anything new to help perform 'one step' creations.

Maybe someone else may have another idea/trick.

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thx alot TurboPT. Thats all the medicine i needed

I was going through all documentation sun.java i was literally losing my mind. Now that i know that java doesn't support this machanism i can go on with my life

I will note the notation you made about how to create the array och class type... Thx again TurboPT

I think your problem is solved.But I want to make it more clear.


This code will print "constructor invoked" one time .
Here obj is an object.

But the same thing in java will not print that statement.
Because obj becomes object reference but not object.
Memory will be allocated only with a new operator ,
obj = new ex();//now constructor will be invoked.

So,the point is when you create an array of your class,it is an array of references in Java ( In C++ it is an array of instances of your class )

In java you have to create the instances of your class using 'new' which invokes the constructor.