File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
http://aspose.com/file-tools
The moose likes Beginning Java and the fly likes This question is about AutoBoxing feature in java Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "This question is about AutoBoxing feature in java " Watch "This question is about AutoBoxing feature in java " New topic
Author

This question is about AutoBoxing feature in java

Ravi Kiran Va
Ranch Hand

Joined: Apr 18, 2009
Posts: 2234

Hi ,

This question is about AutoBoxing, here i am adding some int primitive into ArrayList .
The problem is when i am retriving , it is expecting an Object when i say list.get(1);

The question i am asking is that , If we add a primitive type into a DataStructure , whether Autoboxing feature implicitly converts a primitive into a Object ??




Save India From Corruption - Anna Hazare.
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19785
    
  20

It does. Your problem is that your ArrayList is a raw ArrayList; the compiler doesn't know that it contains only Integer objects. If you change the declaration to the compiler knows that this list will contain only Integer objects, and therefore get(1) will return an Integer. If you are absolutely certain that it does not return null you can use auto unboxing to turn that back into an int:
As I said, only do this if you are certain that the Integer is not null. If it is, the auto unboxing will throw a NullPointerException.

1) it is better to declare as interfaces or abstract classes. If you don't know why search around in Beginning Java and Java in General for the answer.


SCJP 1.4 - SCJP 6 - SCWCD 5 - OCEEJBD 6
How To Ask Questions How To Answer Questions
Ravi Kiran Va
Ranch Hand

Joined: Apr 18, 2009
Posts: 2234

Thank you very much .

Your code helped me .
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: This question is about AutoBoxing feature in java