1) Difference between synchronized and concurrent collections in Java. 2) what is concurrency? relation with synchronization? 3) synchronized keyword? 4) experience with performance and load testing 5) difference between inner join and outer join 6) how do you optimise a slow performing query 7) Advantages of normalization in database 8) stored procedures vs functions 9) some multithreading related questions (don't remember exactly) 10) Heap vs stack memory 11) difference between constructor and method 12) HTTP methods - PUT, GET, POST 13) why arraylist doesn't store in contiguous memory locations 14) hashtable vs hashmap 15) wrapper classes in java 16) is java 100% object oriented 17) access modifiers in java 18) types of constructors in java 19) final keyword 20) spring data annotations 21) advantages of dependency injection 22) ArrayList vs hashmap 23) difference between finally, final and finalize keywords in Java