Informatica Senior Developer interview questions

1) What are Java Collections and the difference between each interface in the collection 2) what is the volatile keyword. 3) How can you detect a loop in a linked list. 4) Write a code to find the duplicate occurrences of char in the string. Example: String a = "abbcdddebbddccceeff"; Answer: 9 Once I answered this then the complexity is increased to also count string like bbdd, ccee, eeff and answer is 13 5) sort 3 integers using Math.max or Math.min and without using inbuilt sort methods or operators like (>, <). 6) Asked a few questions about my experience related to Restful APIs. 7) How to avoid race conditions in threading 8) Asked questions on null values in collections and the difference between linked list and Array with examples.

Questions on Linked List, Trees, multi-threaded