Application vulnerability due to Non Random Hash Functions

Question

Below excerpt is from an article that explains possibility of Denial Of Service(DoS) attack because of non random hash functions used in Hash Data Structures.

Answer 1

Java HashMap/HashTable can do the 'resize' operation when the filled entry reach threshold. It's hard to say that there have an fixed bucket HashMap waiting for you. Because of the operation for selecting bucket have two steps: one is take hash value of specified key; another primary step is remainder operation with total bucket size(the size has being changed by 'resize').