Win a copy of Soft Skills: The software developer's life manual this week in the Jobs Discussion forum!
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

Limited no of Objects

 
faisal hameed
Ranch Hand
Posts: 48
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Ranchers ! Can we restrict someone to create a limited objects of a class ?
 
Miklos Szeles
Ranch Hand
Posts: 142
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Yes you can. You can create a private constructor for your class and you can create a static factory method which creates an instance of your object. In this method you can increment a counter, and throw an exception/return null, when the limit is exceeded.
 
Rahul P Kumar
Ranch Hand
Posts: 188
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
use singleton pattern, there you maintain a global counter, which tracks the number of objects created and keeps a reference of them. Oncecounter exceeds, you do not allow to create any further object of your class.
 
leroy tsruya
Ranch Hand
Posts: 57
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
sorry my mistake...
 
sujith Acharya
Ranch Hand
Posts: 60
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
yes you can. Give the responsibility of creating the object of the class, to the class itself (which takes care how many objects have been created) by making its constructor private and creating one public static method which creates the object of the class and returns to the client.

 
Campbell Ritchie
Sheriff
Pie
Posts: 47216
52
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Agree. That is a variant of the singleton pattern.
 
Gerbrand van Dieijen
Ranch Hand
Posts: 30
  • 0
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
sujith Acharya wrote:



Minor note: the above code is not thread save. So in case you're accessing getObject from multiple threads (which usually happens when used within a webapplication) you'll need to add the synchronized keyword:



Else you'll might get more objects than wanted, if getObject gets executed at exactly the same time.
 
Don't get me started about those stupid light bulbs.
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic