java collection backed up by multiple collections

Question

I have two collections: coll1 and coll2. I need a collection coll which is the union of the two, but I don't want to allocate a new collection. I simply what coll to represent a view of the two collection, and to forward calls to them.

Is there a library which offer this?

Answer 1

Perhaps Guava's Iterables.concat would meet your needs?

https://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/collect/Iterables.html#concat(java.lang.Iterable)