Java Array

[Sac Anand]

Hello All,

In java, everything is in class, even main method can not be declared outside class like in C/C++.

Then where does length property (to find length of an array) comes from?

Also, when we declare a primitive array (or for object array), an object is created in heap memory, now every object is an instance of some class. Which class' object is created for arrays.

Regards,
Sachin Anand

[Andrea Z�rcher]

Hi Sachin

Yes, in Java arrays are always objects, regardless of what the array holds. I would say, an array is a complex data type.

Andrea

[Barry Gaunt]

Try:

 System.out.println(new int[0].getClass().getName());
 System.out.println(new Integer[0].getClass().getName());

You can possibly use Reflection on the class obtained by getClass() but that's far beyond the scope of the SCJP scope.
[ October 08, 2006: Message edited by: Barry Gaunt ]

[Sac Anand]

Hello Barry

I am preparing for SCJP and may be this is out of scope for the exam but i would really appreciate if somebody can throw some light on this. Actually, this question came across while my preparation for SCJP.

Below line of code gives "java.lang.Integer"

System.out.println(new Integer[0].getClass().getName());

But nowhere in Integer class there is length property.

Regards,
Sachin Anand

[Barry Gaunt]

It does not print "java.lang.Integer" but "[Ljava.lang.Integer;". That is the internal name of the Integer[] class. As I wrote previously you will have to learn to use the Reflection API to investigate further, or you will have to look at the Java source code.

[Sac Anand]

Alright Barry, I'll do further investigation.

Thanks for your help.

Regards,
Sachin Anand

[Praveen Babu]

See this post,

http://www.coderanch.com/t/258624/java-programmer-SCJP/certification/length-property