Pergunta de entrevista da empresa Reserve Bank Information Technology

- Diff between StringBuffer and Builder - Answered - Immutability means? - Answered - gave me a code to check string in. paragraph - i did solve but in long way - there was a one liner. -Does HashMap have null key and what is the index - I answered but fumbled with the second part of question - i knew it was 0 - Default size of Hashmap - did not know at the time -one more code with arrraylist - i explained my logic did not write code as i thought thats what they are looking for the approach arraylist with random numbers - return a list which will have smalled number in zeroth index and max number in last index and the rest of the number sequence remains unchanged - used pointer approach and explained and it works - i came home and solved it as well. - Springboot: Bean scope - singleton - how to change - using @Scope annotation - which annotation to use when you want to make yur id o be unique in entity - @Id @GeneratedValue(Indentity) - this is what i answered - but he was not convinced. - http calls get, put, post, delete, patch diff between put and patch - what does 201 status code mean - i said success with but could not answer this - i checked success with creation of new resource 400 error - error from client what specific - he expected me to say bad request maybe i said the above line - 401 - unauthorized 404 - not found -difference between delete and truncate - answered with examples - and rollback difference possible in delete but not truncate.