Comments on: Importance of specifying initial capacity while instantiating ArrayList and HashMap

By: Venkat

Venkat — Tue, 05 May 2009 12:52:54 +0000

I would say be more liberal when specifying the initial capacity for temporary object. For long living objects you can always call trimToSize() method to minimize the object storage.

By: Jon

Jon — Mon, 04 May 2009 21:25:23 +0000

Any thoughts on how conservative/liberal to be when estimating the size of the collection? Is it better to waste memory by allocating too much space or to waste resources re-creating the area?

By: Venkat

Venkat — Tue, 14 Apr 2009 00:07:55 +0000

Thanks Kiran for your comments.

By: Kiran

Kiran — Mon, 13 Apr 2009 13:55:34 +0000

This is really good Post.
Arraylist will increase its size by using following:
int newCapacity = (oldCapacity * 3)/2 + 1; // extract from ArrayList class

By: Mohit

Mohit — Fri, 27 Feb 2009 08:56:14 +0000

Really Very Good Post…………

By: Venkatachalam Sadasivam

Venkatachalam Sadasivam — Fri, 15 Feb 2008 10:15:37 +0000

A comment received from my friend:

One small correction in this example that is creating an object of ArrayList to an ArrayList reference. It would be more appropriate if it is a List or Collection reference (create object to super class or interface reference when ever possible).

Secondly, ArrayList will increase the capacity to 50% where Vector will double the size. I mean second time it will increase the size by 16 (50%) and not 20 which is double.

Thanks Sajeev and Hari.

By: Narender

Narender — Wed, 06 Feb 2008 19:36:56 +0000

hi,
good post