Get keys from HashMap in Java

A HashMap contains more than one key. You can use keySet() to get the set of all keys. will store 1 with key “foo” and 2 with key “bar”. To iterate over all the keys: will print “foo” and “bar”.

Hash table runtime complexity (insert, search and delete)

Hash tables are O(1) average and amortized case complexity, however it suffers from O(n) worst case time complexity. [And I think this is where your confusion is] Hash tables suffer from O(n) worst time complexity due to two reasons: If too many elements were hashed into the same key: looking inside this key may take O(n) time. Once a hash table has passed its load balance – it has … Read more