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Secrets Of The Masters: Core Java Job Interview Questions

JDJ Enterprise Editor Yakov Fain Offers 30 Core Java Questions You Might Expect During Job Interviews

 

For senior-level developers:

** Q21. What's the difference between a queue and a stack?

A. Stacks works by last-in-first-out rule (LIFO), while queues use the FIFO rule
** Q22. You can create an abstract class that contains only abstract methods. On the other hand, you can create an interface that declares the same methods. So can you use abstract classes instead of interfaces?

A. Sometimes. But your class may be a descendent of another class and in this case the interface is your only option.
** Q23. What comes to mind when you hear about a young generation in Java?

A. Garbage collection.
** Q24. What comes to mind when someone mentions a shallow copy in Java?

A. Object cloning.
** Q25. If you're overriding the method equals() of an object, which other method you might also consider?

A. hashCode()
** Q26. You are planning to do an indexed search in a list of objects. Which of the two Java collections should you use:
ArrayList or LinkedList?

A. ArrayList
** Q27. How would you make a copy of an entire Java object with its state?

A. Have this class implement Cloneable interface and call its method clone().
** Q28. How can you minimize the need of garbage collection and make the memory use more effective?

A. Use object pooling and weak object references.
** Q29. There are two classes: A and B. The class B need to inform a class A when some important event has happened. What Java technique would you use to implement it?

A. If these classes are threads I'd consider notify() or notifyAll(). For regular classes you can use the Observer interface.
** Q30. What access level do you need to specify in the class declaration to ensure that only classes from the same directory can access it?

A. You do not need to specify any access level, and Java will use a default package access level.

The J2EE questions are coming soon. Stay tuned for Yakov Fain on Live SYS-CON.TV. Ask your questions to Yakov on the air!

More Stories By Yakov Fain

Yakov Fain is a Java Champion and a co-founder of the IT consultancy Farata Systems and the product company SuranceBay. He wrote a thousand blogs (http://yakovfain.com) and several books about software development. Yakov authored and co-authored such books as "Angular 2 Development with TypeScript", "Java 24-Hour Trainer", and "Enterprise Web Development". His Twitter tag is @yfain

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Most Recent Comments
Raghu 07/09/08 10:38:32 AM EDT

A message to all,interview questions given here can be generic ONLY.Its not like for 2+ years,4+ years etc.It purely depends on the company and the role for which you are interviewed.Some of the interview questions i faced recently.I was able to clear all the theoretically related so they asked me by giving a scenario.

1. You need to read all the details from say.. www.yahoo.com/index.html, save it in a file in yor local PC. What API will you use in Java and what method??
2. You are saving a set of employee names and their salaries in a HashMap like that.. How will you sort them in descending order based on the salary?
This can be done by implementing the comparator interface.

If you need further information,drop a mail 2 [email protected]

Cheers,
Raghu

aruna 06/20/08 02:40:58 AM EDT

Hi,
Could you please send me the interview questions in java,jsp,struts,jdbc,corejava for 1+ yers of experience as software engineer.

Thanks you,

Ashvini 06/16/08 12:23:12 AM EDT

Hi,
Could you please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as software engineer.

Thanks you,
Ashvini. S

. 06/13/08 04:29:20 PM EDT

these questions are stupid

these are moronic questions that idiots that don't know how to interview asks

lets get to some real world questions

deepa 06/11/08 07:48:12 AM EDT

Please send me expert level questions on jdbc 4.0

sandeep 06/06/08 04:55:35 AM EDT

try http://www.java-interview.com for all the java related interview questions

shikha 05/30/08 04:05:33 AM EDT

please send me the interview questions in java,jsp,jdbc,corejava for 1+ yers of experience as a software engineer.
thanks you,

sreekanth 05/28/08 04:29:58 PM EDT

Thank you very much for such a good article.....as I'm in search of job this article would certainly be helpful for my preparation.

sandeep 04/20/08 04:13:09 AM EDT

please send me the interview questions in java,jsp,jdbc,corejava for 1+ yers of experience as a software engineer.
thanks you,
sandeep

siddharth 04/18/08 07:54:20 AM EDT

I have 1+ yrs experience of working in java.. please help me by sending the interview questions..

varun 04/05/08 06:38:16 AM EDT

Data Migration/Conversion: It can be used to convert sql server tables into mysql tables

rajyalakshmi.M 03/26/08 12:53:10 AM EDT

I need the type of questions asked in an interview for a job in java/j2ee foe 2+ years experience

Thanks

Ranjani 03/12/08 09:39:19 AM EDT

I need the type of questions asked in an interview for a job in java/j2ee with about 2 years experience.

Thanks

archana 03/07/08 04:51:00 AM EST

Hi,
Could you please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as software engineer.
Thanks you,
Archana.

sony 02/01/08 09:37:29 PM EST

I have acquired abt 4-5yrs of Java/J2EE exp and will be attending an interview in the States...Could you pls let me know on what are the tips that I need and pls help me with some questions that they will ask me?

srinivas 01/20/08 07:28:34 AM EST

plz send j2ee interview questions with 2+ exp

Mitesh 01/12/08 12:40:28 AM EST

I need to Prepare for Internship as Java Programmer

VANI SARIN (Recruiter at GE Healthcare) 01/03/08 05:03:29 PM EST

GE Healthcare is hiring Sr. J2EE Developer and Web Client Developers with Ajax and or googleweb toolkit.

Please visit www.gecareers.com and enter job #s 756156 and 756161

vani 01/03/08 12:58:02 PM EST

can u plz send me 2+yrs core,jsp,servlet,jddbc questions

nirupama reddy 11/14/07 02:05:53 AM EST

hi,plz send me 1+ yrs core,adv,servlets,jsps questions

Y.V.Rajesh 11/07/07 01:31:27 AM EST

what is the need of constructors and what is the difference between class variables and instance variables?

sankari 11/02/07 04:56:36 AM EDT

hi,plz send me the 2+yrs exp questions in java/j2ee

praveeb 10/16/07 11:15:51 AM EDT

Hi,send me the 2+years interview questions please

prashant 09/19/07 08:19:58 AM EDT

Hi,
please send me the interview questions in java,jsp,jdbc,corejava for 2+ yers of experience as a software engineer.
Regards
Prashant

Rahul 09/05/07 08:09:02 AM EDT

Hi,
please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as a software engineer.

Regards,
Rahul Deshmukh

Rhea 08/14/07 01:07:54 PM EDT

Hi, I have acquired abt 4-5yrs of Java/J2EE exp and will be attending an interview in the States...Could you pls let me know on what are the tips that I need and pls help me with some questions that they will ask me?

gayatri 08/14/07 03:30:11 AM EDT

Hi,
I have 2+ yrs exp on java ,j2ee
I want some exp interview questions
and project Expletion]
plz help me

Soumitra 08/01/07 10:32:55 AM EDT

need some middle-level/expert-level core Java/EJB/JSP/Servlets Questions and answers

Srinivasarao Pentakota 07/28/07 07:40:00 AM EDT

Hi,
I have 2+ yrs exp on java webtechnologies,i am completed M.Sc Applied Mathematics and i have applied for Software companies but no calls for interviews .what is the reason???/

surya 07/20/07 08:06:29 AM EDT

some of the answers are wrong given by the other person so plz. beware of this.Go for RND and make it sure whether the answer is right or wrong

Svaba 07/20/07 06:09:40 AM EDT

Questions are exilent. I wrote a technical test few days ago and I had few qestions from this list.

Infernoz 07/13/07 04:31:45 PM EDT

Q2 Answer has confused grammar, so maybe part wrong.

Q3 Answer is only half right.
synchronized blocks are not for saving time they are for locking a specified object (which maybe a class), so that one thread owns that object while executing inside the block, they can be less efficient and less safe that synchronized methods, you can even have nested synchronized blocks for different objects, but that can be an invitation for Thread deadlocks and maybe a sign of poor coding practice.

Q17 Answer is correct, for runtime Atul Gupta!

Q19 Answer .. and (from recent Sun advice) for the creation of active Swing and AWT objects like JFrame, JWindow, Frame, Window etc.

Dave the Free Credit Report Guy 07/12/07 08:54:50 AM EDT

Oh yes, it would be totally helpful to master these important Java basics before getting out there for those job interviews...Good job!

Atul Gupta 07/12/07 03:29:45 AM EDT

Hi,

The answer to Question 17 is wrong, it wont give in any compilation errors.

Durga Prasad 07/04/07 02:39:07 AM EDT

Hi,
please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as a software engineer.
Regards,
Durga Prasad A.

Rajalakshmi K 06/25/07 12:51:56 AM EDT

I need some middle-level/expert-level core Java/EJB/JSP/Servlets Questions and answers

Govindaraj.S. 06/18/07 11:08:27 PM EDT

Hai,
Please send me the java question papers in programs also for 1.5+ years of experience

Govindaraj.S. 06/18/07 11:06:11 PM EDT

Please send me java and j2ee question papers for 1.5+ years of experience

N.V.Balasubramaniam 05/24/07 04:14:18 AM EDT

Hi,
please send me interview questions in core java,jdbc,servlet,jsp,struts,teradata,unix,coldfusion,SQL which is generally asked for 2+ years experience.

Thanks in Advance for your Help.
With Regards,
Bala

Amit 02/22/07 02:22:48 AM EST

Hi,
please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as a software engineer.
thanks you,
Amit

Anand 12/27/06 01:13:11 PM EST

All the interview questions are answered here,
for each topic the complexity increases in ascending order, so as your experience grows you can get deeper in each topic.

http://www.java-interview.com

I just love this site

akumaran 11/02/06 02:15:07 AM EST

Very good questions and answers. Also would be nice to add a "How would you go about..." section. Sometimes the candidate does not have to know the exact answer (e.g. performance, memory profiling etc) but should know how to go about solving a given problem or a task. Some other useful Q&A covering wide range of topics relating to Java/J2EE can be found at http://www.lulu.com/java-success and also google for "Java Job interview questions" or "J2EE Job interview questions"

himanshu 09/19/06 05:35:55 AM EDT

Hi,
please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as a software engineer.
thanks you,
himanshu

sachin 09/17/06 02:36:59 AM EDT

Hi,
please send me the interview questions in hibernet and EJB for 3 yers of experience as a software engineer.

madhavi 09/16/06 01:37:04 AM EDT

Hi,
please send me the interview questions in java,jsp,struts,jdbc,corejava for 2+ yers of experience as asoftware engineer. Also i need satyam papers also.
thanks you,
madhvai.

prajjal nag 09/15/06 03:19:48 AM EDT

Please send some interview question for Core Java for 2+ yrs experience, preferably java 1.4 and java 1.5

ABDULLAHI ABUBAKAR 09/14/06 08:30:00 AM EDT

I want you to send me the questions because i will start to study, Certified Enterprise Developer and Solution Architect on Sun Java Platform in this year.
Thanks.

Peter 09/14/06 05:59:12 AM EDT

Hi, I need some interview questions for a Java/J2EE Developer role, it's a phone interview taking place within the next 2 hours. any immediate help will be deeply appreciated.

surya 09/09/06 12:01:25 PM EDT

Hi,
please send me interview questions in core java,jdbc,servlet,jsp,struts which is generally asked for 2+ years experience
and aslo ibm,satyam interview questions.

imran 09/07/06 09:56:10 AM EDT

asdgsda

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