Some Interview Quetions

why use locks instead of synchronization?
How to stop a thread?
Executor service ?
rules of overriding?
How to serialize singleton?  
Different Java GC algorithms  
How hashmap works internally?
 future callable 
 BFS and DFS, trees, graphs hash maps 
What is left inner join 
What are the SOLID principles?
What is the difference between a clustered and a non-clustered index?  
How to join two sorted linked lists such that the resultant linked list is a sorted list?  
Print all palindromic substrings (should contain only alphabets) in a given sentence.
Find the total number of ways a person can go from A to B if he can take either 1 step or 2 steps. 
Find all substrings in a string which has exactly K unique characters.  
Design and separating Concerns,Trees and Arrays
Find two integers in the BST whose sum is equal to K....
Answer - Try to solve this problem using two stacks nd not by recursion) .....

Finding the smallest path between any two nodes in a tree. 
NCS Interview Quetions:
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Q: why use framework, why spring MVC, why hibernate, what problems they are solving
Q: tell what you know about data collections, each collection when to use it and how it can be used.
Q: hashmap , can an object be the hashmap's key and how to use it?
Q: when to use Array and when to use ArrayList
Q: How to make a class Singleton.