Citi Bank Telephonic Interview

Telephonic interview started with basic introduction about my project and what I've contributed towards this project. And then direct question on Java

Core Java questions -

• Does java allow primitives in Generic types ? Why not
• Collection interface
• What is hierarchy of collection and Map interface
• Difference between HashMap and HashSet
• Given an employee class, what are the things you would like to take care of when overriding HashCode method
• When will you use a List over a HashSet. Benefits of using a list or an array ?
• Difference between HashMap and HashSet, can we have null keys in HashMap, Can we have null values in HashMap
• Alphabetically sort  a list of Strings in Java
• Serialization ? Give real world example, when you would like to use serialization
• What is heap memory, can heap memory equal to RAM space. How will application behave if we make heap memory equal to RAM space
• Is there any memory threshold when defining head space
• In a 4 CPU processor, how many threads can run in parallel. If we have 4 thread when will 5th thread run
• Can we tell compiler to run 5th thread based on our program
• What are concurrent APIs ? How they help us.
• Do you know permGen

SQL -

• When will you use indexes
• What are views
• Table joins queries

Questions related to my profile -

• When will you prefer Rest over Soap
• Is there any threshold on amount of data that can be sent over SOAP and after which we should prefer REST
• In non mobile application, possibility of using rest
• Many questions on why SOAP is preferred over Rest, scenarios where you would prefer Rest
• WSDL equivalent in SOAP
• When you would prefer MongoDb over Sql databases
• Are transaction supported in MongoDB