J. Moldawski created COLLECTIONS-450:
----------------------------------------
Summary: Iterate over the all elements excluding the last/first one
Key: COLLECTIONS-450
URL: https://issues.apache.org/jira/browse/COLLECTIONS-450
Project: Commons Collections
Issue Type: Wish
Components: Collection
Reporter: J. Moldawski
Priority: Minor
The Problem
============
In many applications you will extremly often find this sort of code:
int i=0;
for (element:elements)
{
i++;
if (i!=elemets.size)
{
processLastElement(element);
}else
{
// Just for last element
processLastElement(element);
}
}
It happens often, if not just all collections's elements themself must be
processed, but some actions must be performed on going from one element to the
next. Since the last element has no successor, this actions must be skipped
when processing the last element. A very famous example is, if your are going
the generate a comma-separated-vector from a Collection<String>: You will end
up in a code like above.
Proposal
=========
The method <T>CollectionUtils.forAllButLastDo(Collection<T>, C)
should be introduced, which process all elements of a collection, but skips the
last one, which will be just returned. The above code can be then re-written:
processLastElement(forAllButLastDo(elements,
new Closure<T>{
execute(T element){
processAllButTheLast(element)
}
}
))
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