1. Implement equals and hashcode?
  2. Internal implementation of hashmap?
  3. Palindrome program?
  4. Fibonocci program?
  5. Thread pool implementation?
  6. Volatile?
  7. Semaphore, cyclic barrier, countdownlatch?
  8. Word count program?
  9. Implementation caching?
  10. GC algorithm implementation?
  11. Diff btwn JVM, JRE, JDK?
  12. How to create a read-only arraylist?
  13. Why String is immutable?
  14. What is an intern() function in String used for ?
  15. Serialization?
  16. When to use externalization?
  17. Shallow and Deep copy? implementation?
  18. Singleton design pattern
  19. Model -View-ViewModel design pattern?
  20. Proxy design pattern?
  21. Factory design pattern
  22. Agile planning?
  23. Single sign-on implementation?
  24. udp and tcp?
  25. Spring components? IOC? AOP?
  26. REST Webservices? synchronous API , unsynchronous api?
  27. How to make the thread to wait for other threads?
  28. How to stop the thread?

SQL Questions

  1. query to find the 3rd largest salary from the employee table?
  2. self join? why it is used and when to use?
  3. clustered index and non-clustered index?
  4. How B-tree works?
  5. JDBC

Why was the ConcurrentHashMap and other such collection classes introduced in Java?


JVM internals ?


What happens when you create an object? i.e when you say a = new ClassA() ?



Proxy class in Java? How to do that ?



This is only for Proxy Design pattern, the actual answer is in h.

  1. Give the architecture diagram for a standalone Employee Management System
  2. Give the algorithm for Find and replace a substring from a string using
  3. How to do the debug of an application if an exception is not caught, how will you know where the error has occurred?
  4. If a third party API is not behaving correctly in a prod environment how to fix the issue ?

When we dont want to change the API’s that is getting called (the API which is misbehaving,) we can use Java’s Proxy class.



ADF is based on what kind of mechanism ? He wanted me to answer something on Tag libraries

REST API came from which change in Java and which version ?

The answer I didnt know was, Annotations. REST API’s became successful after the Java 5 started Annotations.

In REST how to handle versioning




Differences between SOAP and REST API’s


The REST API lifecycle and architecture , especially what happens when the user calls a GET method.



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