Faster Java – Strings

If you’re building a long String in Java, don’t stick String objects together using ‘+’, for example:

String str = "Hello";
str = str + world;
str = str + "!";

Why not?

It’s really slow when you do it a lot!

What should you do instead?

Use the append(String) method in StringBuffer (Java 1.4.2 on), or StringBuilder (Java 5 on). StringBuilder is slightly faster than StringBuffer, but is not thread safe. Both are much faster than concatenating String objects – by orders of magnitude. For example:

StringBuffer str = new StringBuffer("Hello");

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Semantic Web@Geekup Sheffield

For anyone curious about this Semantic Web thing, you could check out Ian Ibbo’s introductory slideshow…

It’s the first part of series he’s doing at the Sheffield Geekups over the next few months, so there’s more if your appetite is whetted. There were rave reviews from the introductory talk…Next one will be at Sheffield’s Showroom cinema on the first Wednesday of February.Cheers!

Logic for Dummies – Part 1

It seems like one of the things I really have to get my head round if I want to understand some of the principles of computer science is logic. Now, I figured that would be easy. I mean, I can remember truth tables for AND, OR, NOT, NOR, NAND, etc. from school, so how hard can it be?

Yup, how hard can it be – the classic sign of someone who doesn’t know enough about the problem to know that they don’t know enough about the problem. Continue reading