Interviewer was friendly. Some/all of the questions he asked. diff between int and Integer diff between == and equals() what do u need to do when you override equals() and why? diff betn abstract and interface what is enum class have you used JMX at all? what is a thread? how do you create a thread in java? what is thread and runnable ? does the threads start automatically when you create them? what are the problems with multi threading? how to avoid them? what is synchronization? when you create a method with synchronize, is the method synchronized? or the variables? if one thread is running the method, can other threads run other methods in the class? what is the downside of synchronization? what is serialization? how do you achieve this in java? what is the difference between the class that extends Exception and RuntimeException? what are checked/unchecked exceptions? Have you done any UnitTesting? have you used JUnit/TestNG? difference between ArrayList and Vector? What is aspect programming? what is dependency Injection? Do you have experience with Ant/Maven ? What is final variable,method, class? What are the different parsing methods available to parse XML? diff between DOM and SAX? diff between http GET and POST? diff between TCP and UDP? what command do you use to check the running servers in UNIX/LINUX environment?