1. quick , merge sort 2. hibernate caching 3. sessionfactory vs session 4. Spring DI, constructor vs setter DI, which is better 5. exception vs error 6. runtime vs comile time error, need 7. classDefException vs noClassfoundExcption ,which 1 occurs at compile time,how to avoid compile excption 8. arraylist vs linkedList 9. hashset 10. datastructure for hashset n arraylist 11. internal working of hashset 12. Employee e =new employee(); Employee e1= e; e == null; syso(e1) ?