Comments on: Java Collections Cheatsheet – v2

By: Java List Efficiency | Software Talk

Java List Efficiency | Software Talk — Sat, 21 Jan 2012 21:22:58 +0000

[...] I found this nice cheat sheet for Java collections. [...]

By: Maurice Naftalin

Maurice Naftalin — Fri, 24 Sep 2010 19:18:14 +0000

@Suresh: The remove operations compared in the book and the cheatsheet are on iterators, and iterator.remove() does have complexity O(1) for a linked list (same pointer-swinging involved, wherever the element occurs)

By: Suresh S

Suresh S — Thu, 23 Sep 2010 08:07:38 +0000

when you delete an element in the middle of the linkedlist i think it is O(n) not O(1).kindly clarify if i am wrong.

By: Site de Cheat Sheets | Serviço Técnico de Informática

Site de Cheat Sheets | Serviço Técnico de Informática — Wed, 30 Jun 2010 22:03:18 +0000

[...] de uma grande parte das linguagens de programação e aplicações. Por exemplo, referências das Collections do JDK ou as referências standard de [...]

By: coder-friendly

coder-friendly — Fri, 11 Sep 2009 14:34:17 +0000

Hello,

Since the answer of Maurice Naftalin(author of the book) is relevant, I’ve removed my previous answer because it would upset other future readers.

Thank you Maurice for your answers.

Coderfriendly

By: Maurice Naftalin

Maurice Naftalin — Thu, 10 Sep 2009 13:35:22 +0000

The other comment is also wrong:

log 2n = log 2 + log n

(see, for example, http://en.wikipedia.org/wiki/Logarithm), so the statement (in both book and cheatsheet) that “if N is doubled, the running time is increased by a constant amount” is correct.

By: Maurice Naftalin

Maurice Naftalin — Thu, 10 Sep 2009 09:27:16 +0000

Contrary to the comment from Neverwinterx, the cheatsheet is correct if slightly ambiguous. It gives the complexity of remove(0) – the first element of the list.

There is no remove(O) method on List. There is, however, a method remove(Object) and, yes, that has linear complexity. But the book and the cheatsheet don’t discuss that.

By: Neverwinterx

Neverwinterx — Sun, 06 Sep 2009 12:50:21 +0000

There’s an error in the cheat sheet. The remove(O) operation of LinkedList works in O(n), not O(1). You can check it for yourself in the source code.
This seems to be a common misconception, i’ve made a post about it here: http://forums.sun.com/thread.jspa?threadID=5406078

By: Cornelius Perkins

Cornelius Perkins — Fri, 04 Sep 2009 03:36:46 +0000

Small correction: O(log n) probably shouldn’t be described as the running time increasing by a constant amount. It’s actually by the square root of 2, but that means the growth is nonlinear: it has a curve, steeper than linear… but of course, much shallower than n**2.

However, the cheat sheet itself looks fantastic. I’ve just printed it to study it in detail. Thanks for the great work.