Filter out list of elements in a "lazy" way

Question

I have a list of objects and I want to create another list, which will include only objects for which the method acceptable() returns "true". My problem is that I want to make this selection done only on demand. In other words, I want a new list to be calculated and populated only when its iterator() method is called. Are there any libraries for that in Java?

I'm using JDK7

Answer 1

Google Guava has a lot of helper methods for that type of functionality. What you want is already implemented.

Iterators.filter if you want to fiter an Iterator from a collection.

Iterables.filter if you need an instance of Iterable, for example to use it in "for-each" type of loops.

There is also Collections2.filter if you need also other collection methods to be preprocessed with the filter.