CODEWITHSUNDEEP
javacollectionshashmapsethashset
Soner from The Ottoman Empire
Soner from The Ottoman Empire

Reputation: 20901

Java API - Dead-end on entrySet()

When examined Java's hierarchy Set and Map are different interfaces and Map doesn't implement Collection interface. Set is used to hold unique values regardless of ordering, while Map is used to unique keys and mapped values without ordering(except through LinkedHashMap, TreeMap). AFAIS, the major common part is that both of them make use of hash tables to store. My question is about entrySet() method. I just know about the method that it is used to iterate through to get key and mapped value with the key.

I have gotten the structures as different from each other. But it seems both take advantage of each other. It is a little bit vague to comprehend. Can you illuminate?

Upvotes: 1

Views: 52

Answers (1)

Eran
Eran

Reputation: 393791

Why does its return type use Set>? I mean why Set, why not ArrayList or something?

A Set is the preferred Collection type to use for a group of unique elements with no ordering. The entries of a Map are unique, since the keys must be unique. And the base Map interface assumes no ordering on its entries, so a List of entries wouldn't be appropriate.

Does postfix of the method(set) express something why entrySet why not entryFoo or entryMap (it's already the method of HashMap)?

It returns a Set of entries, so entrySet() makes perfect sense.

Upvotes: 1

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