Java – calculate occurrences in Multimap

I have a Multimap with multiple similar values:

{Entertainment=[5],Food=[2,2,2],Products=[11],Health & Beauty=[3]}

How to calculate the total number of these keys as follows?

Entertainment = 1
Food = 3
Products = 1
Health & Beauty = 1

The number in the array is the category ID, so food appears three times

Solution

multimap. get(key). Size () or Multimap keys(). Count (key) should work

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