Useful Stuff - Interview Questions

Here are some interview questions you might find useful.
I have 3+ yrs of Work Experience primarily in Java/J2EE, Oracle Applications, and Oracle Applications Framework.
So, people with > or < experience that me can expect an increase or decrease in the standard of the questions you might end up getting.


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CURRENT PROJECT
===============

1. Explain Business Requirement/Domain Need to which the product caters to.
2. Explain Architecture of the application.
3. Roles and Responsibilities in current project.
4. Participated in which all stages of the SDLC.
5. Which Software Development Model is used for the project. What is the business need to use this model.

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PL/SQL
======

1. Exception Handling.
2. Collection Objects.
3. Cursors.

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SQL TUNING
==========

1. Need for hints.
2. Name a couple of hints.
3. Performance implication of IN clause.
4. Advantages of IN v/s EXISTS.
5. Maximum number of parameters IN clause can take.
6. How does SQL Engine work.
7. Explain Plan - How is it calculated/decided.
8. When to go for denormalization/normalization of tables.
9. How to read a trace file.
10. Is full table scan always a bad thing.
11. When does an Index degrade performance.
12. What are the different types of indexes, and when and where should they be used.
13. Does using a hint ensure that the SQL Engine will follow the instruction specified in the hint.

===
SQL
===

1. How to lock a row in the table without performing an update command.
2. What is Outer Joint.
3. How to get the 3rd highest value of an attribute in a table.
4. Design criteria for deciding what all attributes will go into a table, and number of tables needed.
5. WHO Columns - What is the business need for such columns in a table.
6. Do you use index on String fields on a table. If yes - what is the performance implication of the same.
7. How do you partition data/tables to ensure maximum performance, especially when tables have 10's of millions of rows of data.
8. How can you do clustering of a D/B.

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JAVA
====

1. OOPS Concepts.
2. Difference between Abstract Class and Interface.
3. Why doest object class contain methods like wait(), waitFor(), notify(), notifyAll().
4. Why should all classes extend Object.
5. If Class A extends B, then how does A extend Object - since one class can only extend one class.
6. How can you load/unload a class which has been loaded by the JVM.
7. How to write Custom Classloaders.
8. What are the different interfaces in Collections.
9. Linked List - What is the advantage of using it in Java.
10. What is the significance of having a datastructure like linked list.
11. Performance of Linked List v/s ArrayList.
12. Difference between ArrayList and Vector. Which and Why and Where would you use these collection objects.
13. If you had to add 1 million objects to a particular collection object, which collection objection would you use and why.
14. Feature differences/advancements in Java 1.6 v/s 1.5 v/s 1.4
15. Usage of Iterators.
16. Garbage collection.
17. What are the different ways in which the JVM decides which objects are ready for Garbage Collection.
18. Why is a method like System.gc() given - when there is no assurance of the GC being called.
19. Give a practical need/use of overloading the finalize() method.
20. When and Why does a programmer have to do a System.gc().
21. Why doesn't Java give programmers the privilege to overload operators.
22. WHY is String considered a special object. Why is this privelege not extended to other classes.
23. String is an immutable object. Why so.
24. Difference between String and StringBuffer.
25. When is String more performant and useful than a StringBuffer.
26. Why is the entry point of an class which needs to be run from a console - public static void main(String args[])
27. How to write native methods in Java. Is it advisable to do so.
28. Explain what CORBA stands for and the need for the same.
29. Difference between Checked and Unchecked Exceptions.
30. Explain the design condition when would you decide that your method would throw a Checked Exception or an UnCheckedException.
Also, give a real-time example to support your answer.
31. Multi-Threaded Applications - What is your exposure to them.
32. How is exception handling done in Java.
33. What is the business need to have exception handling in Java.
34. Why do we need the finally block.
35. If an application encounters an Error or an Unchecked Exception - does it crash. If not - is it a good idea to continue running it.
36. Have you encountered and Errors, if yes - name them.

====
JDBC
====

1. Types of drivers available.
2. Which is the most performant driver and why.
3. Under which scenarios would and should one use each of the 4 types of drivers.
4. Different Steps involved in JDBC, from start to end, to fire an SQL query and get a resultset.
5. Where would you write the conn.close() - in the method or in a finally block. What is the advantage of doing so.
6. Connection Pooling concepts.
7. Explain what are the standard methods one would need in a ConnectionPool class.
8. Differences between JDBC 1.0 and JDBC 2.0
9. Difference between Datasource and ResultSet.
10. Scrollable Resultset - What is the advantage of such resultsets. When do we need to use such a resultset.
11. How to create a scrollable resultset.
12. Why do we need a Datasource when in the code we can make the URI being referred point to Collection Pool directly,
as a Datasoruce indirectly points to a Collection Pool anyways.
13. If ResultSet/Connection/Statement etc are Interfaces - who gives the implementation of these interfaces.
14. If you were to write your own Driver API - which class would you need to give and implementation of.
15. How to achieve Batch Update.
16. Difference between - execute(), executeQuery(), executeUpdate().
17. Difference between - Statement and PreparedStatement.
18. What is a PreparedStatement Cache.
19. In PreparedStatement - where is the explain plan cached - D/B, Application Server, JVM, Application, Heap Memory.
20. What happens when you fire an "Update ...." command in the executeQuery().
21. What happens when you fire an "Update ...." command in the executeQuery() and zero lines are updated.
22. How do you get SQL Warnings. Name other approaches besides using the getSQLWarnings() method.
23. Which approach is better - firing SQL from Java layer, or invoking a PL/SQL procedure to do the same. Explain.

====
J2EE
====

1. Difference between JSP forward and sendRedirect
2. Implicit Objects in JSP.
3. Session Tracking - Different Methods Used.
4. If cookies are not allowed by the client web browser - does any of the other session tracking methods work effectively.
(Hint - most of the other methods of session tracking internally depend on usage of cookies)
5. How to set a cookie and get cookies from a browser.
6. Explain MVC architecture.
7. Difference between MVC 1 and MVC 2 architectures.
8. What are the latest developments in J2EE.
9. Do you prefer JSP or Servlets. Give real-times examples of when Servlet is more useful than a JSP.
10. Servlet Life Cycle.
11. JSP Life Cycle. How is it different from a Servlet Life Cycle.
12. Difference between Static Include and Dynamic Include.
13. JSF - Have you used it.
14. How do you write custom jsp tags. Have you had to write custom tags in your career
15. Struts - Are you aware of the basic architecture. If yes - Explain it.
16. What are the different Back End Persistance Technologies that are "hot" in the market now. Have you used any of them.
17. How to tune a Web Application.
18. Explain the approach you would follow to identify in which layer the performance is poor and how would you fix this such
that minimal application down time is required.
19. Have you used eclipse plugins like JUnit and JMeter.
20. How to make an application run on a Single Thread Model. What would be the pressing business need to support such a requirement.
21. How to handle the challenge of Different Browsers interpreting HTML Tags in different ways, and also the need to give a rich UI.
22. Difference between GET and POST methods.
23. Max value of URL Length in GET protocol.
24. If I need a servlet to handle a protocol like GOPHER - how would I go about doing it.
25. Describe the Inheritance Architecture of the HTTPServlet.
26. Differences between the HTTPServlet and GenericServlet.
27. How does an HTTPServlet identify an incoming request as an HTTP request.
28. Explain how you would write a proxy server to intercept HTTP requests, process the request and send the output to the user.
29. Servlet Chaining - Why do we need this. How is it achieved.
30. Servlet Filters. Explain the need for the same. How to use it.

==========
WEB SERVER
==========

1. How to achieve clustering.
2. What are the different services that a Web Server provides that your application uses/needs.
3. Web Server Turning - Any exposure