File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
The moose likes Java in General and the fly likes Refrence Types Assignment Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login
JavaRanch » Java Forums » Java » Java in General
Bookmark "Refrence Types Assignment" Watch "Refrence Types Assignment" New topic

Refrence Types Assignment

Tarek Moustafa

Joined: Oct 15, 2012
Posts: 2
I have a question regarding wrapper classes assignment.

When I try the following, it prints false :-
Integer i = 4005;
Integer i2 = 4005;
System.out.println((i == i2) );

while thisone prints true:-
Integer i = 45;
Integer i2 = 45;
System.out.println((i == i2) );
Steve Luke

Joined: Jan 28, 2003
Posts: 4181

First: when comparing Objects of any type, you should use .equals() rather than ==. If you use .equals() you will get consistent results.

Second: The reason == works with some Integer values (those close to 0) and not others (those farther from 0) is because of 'Integer Caching'. See this discussion on the topic.

Rameshwar Soni
Ranch Hand

Joined: Feb 03, 2011
Posts: 247
The same question has been asked many times, so i would request you to search first and if you have any further doubt after searching you can surely ask.
And Welcome to Ranch.
Tarek Moustafa

Joined: Oct 15, 2012
Posts: 2
Thanks, Steve.
And sorry for repetition.
I agree. Here's the link:
subject: Refrence Types Assignment
It's not a secret anymore!