Java interview questions for start up companies

A set of real time java interview questions for internet product companies:
(ngpay, CA, Canvera, Directi, Lime labs etc..)

This will contain 4 sections, viz. java, ds/algo, designing, miscellaneous:

Java:
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1. What are the usages of final keyword?
2. How to make a Map case insensitive with out extending the class or using .toLower on sring.
3. How does a lock work ?
4. Describe the internals of how a thread manipulates the synchronized block?
5. what is the use of finalize()?
6. How to stop a thread?
7. Why in windows the max heap size is limited to 2 Gb?
8. Hows the stack is divided in JVM?
9. Draw the heap layout of JVM?
10. Describe different garbage collection algorithms
11. How to use an unreachable object in Java?
12. 2 scenario where it will produce memory leaks and how to prevent them?
13. If a Map is declared final, can we put objects in it? how?
14. Why we need interface when we have something called abstract class?
15. If I override the hashcode method and return 1, will it always result in the equality of the objects?
16. What do you mean by hashcode of an object? How does it work?
17. Difference between a Vector and a list
18. When to use a ArrayList and when to use a linkedList
19. How is stack implemented in JVM?
20. How to design a synchronized singleton?
21. How to break a synchronized singleton?
22. What are the collection framework API?
23. How a multi threaded application works with monitor?
24. What is the relation between the eauels() and hashcode() methods?
25. How to design one thread pool?
26. Can we prioritize a thread? How?
27. How thread execution is handled by JVM?
28. why string is mutable?
29. what is out in System.out.Print()?
30. How the class loader works?

Update: I try to provide explanation for all the questions asked above. But not sequentially nor question wise. I will write explanation to topics in general which will contain answer to the questions in it.