Map with ArrayList as the value in Java - Why use a third party library for this? -

Map with ArrayList as the value in Java - Why use a third party library for this? -

i've found need utilize map long key , arraylist of objects value, this:

map<long, arraylist<object>>

but read here using third-party library google guava recommended this. in particular, multimap recommended instead of above.

what main benefits of using library simple?

what guava details reasoning , benefits.

for me biggest reason reliability , testing. mentioned has been battle-tested @ google, used elsewhere , has extensive unit testing.

arraylist map guava java