Java Interview FAQ

Below is a list of most frequently asked interview questions in Java. I am not furnishing any answers here because you can easily find them on google for one reason. And for many questions there is no single correct answer. So people are free to post their versions in the comments. Also, please do add to the list any other FAQ which I might have missed.

1. Why is Java Platform independent? How does it acheive it?
2. abstract class vs interface
3. What is polymorphism?
4. What is multiple inheritance? Does Java support it?
5. overloading vs overriding
6. String vs StringBuffer
7. Why is String immutable? How do you make a class immutable?
8. Hashtable vs HashMap
9. What is multi-threading?
10. How do you make a program multi-threaded?
11. What is synchronized?
12. What is final?
13. final vs finally vs finalize
14. How are Exceptions handled in Java?
15. Checked Exception vs Unchecked/Runtime Exception
16. What is serialization?
17. What is singleton design pattern?
18. What are inner classes?