Arrays, ArrayList, and HashMap are all "collections"
of objects. Importantly, they also aren't the only possible
kinds of collections.
Java provides support for a wide range of different collection types through "The Collections Framework."1
Footnotes
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There is nothing really special about these interfaces and classes that mean they deserve such a name. I view it as a marketing term. There was a period of time before which Java did not have
ArrayList,HashMap, etc. and when they were added they said "this is the new collections framework" instead of "we've added these dozen classes." ↩