From: Robert Klemme <shortcutter@...>
Date: 2008-05-22T00:42:01+09:00
Subject: Re: arrays in ruby and java

2008/5/21 Zhe Zen <zhe.zen@gmail.com>:
> hi,
>
> i have been translating an algorithm from ruby to java. unfortunately i
> stuck with one line of code and would like to ask for some help.
>
> My problem is the following line:
>
> b.data[b.data.index(token)+1]
>
> and here is the context(which i not relevant in my opinion):

> my problem is the following: if the array b.data has 10 elements, then
> the "+1" could set it to position 10, so that b.data[10] would give back
> an error, like the  java.lang.IndexOutOfBoundsException, which I get in
> Java, when translating. in ruby the code is working, in java obviously
> not. could somebody give me a hint, where my error in reasoning is.

I cannot see an error in your reasoning.  Ruby's Array and Java's List
just behave differently.

As far as I can see you have at least these options:

1. create an implementation of java.util.List that does not throw but
simply returns nil.

2. do a check in your code and if the index is out of bounds use null
instead of list.get(n)

3. write a static helper method that implements option 2

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end