• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Liutauras Vilda
  • Jeanne Boyarsky
  • Devaka Cooray
  • Paul Clapham
Sheriffs:
  • Tim Cooke
  • Knute Snortum
  • Bear Bibeault
Saloon Keepers:
  • Ron McLeod
  • Tim Moores
  • Stephan van Hulst
  • Piet Souris
  • Ganesh Patekar
Bartenders:
  • Frits Walraven
  • Carey Brown
  • Tim Holloway

doubt from Head First Servlets & JSP

 
Greenhorn
Posts: 9
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I the Head First Servlets & JSP 1.4
page no 202

one statement is there :
And since you're a Java programmer you know that even a final variable can still be manipulated unless it's immutable.

Please clearify me this line with a proper example
 
Sheriff
Posts: 13411
Firefox Browser VI Editor Redhat
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
The "And since you're a Java programmer... " part tells us that this is a core Java issue, not a servlet specific one.

I'm going to move this to our Java In General (Intermedite) forum where this gets discussed from time to time.
 
Ben Souther
Sheriff
Posts: 13411
Firefox Browser VI Editor Redhat
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Here is a nice introduction to Java variables.
It's both easy and fun to read.
http://www.javaranch.com/campfire/StoryCups.jsp

After you read it, remember that final means that the remote can never point to another TV. Nor can you exchange the remote in the cup for another one.

It doesn't mean that the TV can't be altered to play a different channel.

See if that helps.
[ May 23, 2008: Message edited by: Ben Souther ]
 
Greenhorn
Posts: 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Try The below link
http://mindprod.com/jgloss/final.html . It talks about "Blank Final Variables". I think the reference in Head First is regarding this.


Hope it helps.
 
Marshal
Posts: 64661
225
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Welcome to JavaRanch, Amit Kumar Arora.

The "blank final variable" of the Mindprod website you quoted is an intermediate stage; a variable (better called a field) has been declared butnot yet initialised, so it must be initialised by every constructor.

A final field may point to a reference type, but cannot be altered. The state of the object which is that reference type might however be altered. that is probably what the Head First quote means. You can "change the channel" as Benm Souther has told you.
 
It is sorta covered in the JavaRanch Style Guide.
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!