Core Java Interview questions for experienced Java developers

 

  Core Java Interview questions for experienced Java developers

 Well the interview questions for experienced java candidates vary based on the experience and the
  JD. Following is the list of  very frequently asked Core Java questions .

1. What is class loader? 
2. What is are different types of class loader?
3. Can you have two instance of a singleton class?
4. Which class loader is used when you execute main method of the your class, where does it picks searches the file?
5.  What is static class loading & dynamic class loading, give example and difference?
6.  Diff b/w ClassDefNotFound and NoClassDefFound exceptions.
7.  what is checked and unchecked exception.
8.  Draw the exception class hierarchy.
9.  How will you create  your own exception class?
10.  what is  difference between instanceOF and isInstance?
11.  what is difference between final,finally,finalize?
12.  How many types of reference are there in java?
13.  what is soft refrence,weak refrence,phantom refrence?
14.  what is weak hash map?
15. what is stringpool , intern method?
16. what is  diff b/w stringbuilder and string buffer?
17. How do you make a class immutable. example with a class having a date object.?
18. What are Atomic variables?
19. Difference between equals and == ?
20. Draw collection hierarchy.
21. What are concrete implementations of list,set, map interfaces?
22. What is difference between hashmap and hashtable?
23. What method calls would be made internally, when i call get and put  function on a hash map.
24. what is the return value of put function in hashmap?
25. Why do objects have Hashcode and equals method?
26.  How does hash map internally stores the data?
27. What special methods do i need  to implement i want my class object to be key of a hashmap? 
28. Why do objects have equals method? What would the code of equals method look like?
29. Write your own hashmap implementation?
30.  Write your own list implementation?
31.  How can you make a singleton class?
32.  what will happen when you de-serialize a single tone  object having  reference to itself?
33.  LRU CACHE implementation, which Class will you use and why?
34. What is ConcurrentHashMap, explain internal element storage and retrieval by multiple threads?