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what are the most common questions on Java job interviews?

bengt hammarlund
Ranch Hand

Joined: Oct 17, 2003
Posts: 78
I got one interview and I got these questions:
1) define the relationship between a class and an object.
2) define polymorphism.
3) define inheritance.
4) define encapsulation.
I guess that these questions are pretty standard, but I can think of at least two correct answers to these questions, given the space they gave me to write the answers.
How would you answer these questions if you had only 2 or 3 lines to write down?
And what are other questions (not especially Java related, just OO related) that you guys already faced on job interviews?
Thanks for any help. I think this is an important issue, because you think you know this stuff but sometimes they�re hard to answer or define with just a few lines then you would expect.


<b><i>Bengt Hammarlund</i><br />� Sun Certified Java Programmer</b>
Vikrama Sanjeeva
Ranch Hand

Joined: Sep 02, 2001
Posts: 756
Hi,
Today I faced very short_quick interview session on Java. Three questions were asked.
1: How much work u have done in Java?
2: What is JMS?
3: What is the difference b/w Java & J2EE.
My Answers:
1: I have done SCJP. Most of the projects I developed was using Java.
2: It is a Messaging service used in communication purpose. [i don't know about JMS much therefore I stop here.]
3: J2EE is specifically for Server Side development uing Servlets+JSP. Whereas Java is part of J2EE as a language.. and u can develop Desktop Applications in simple Java.
For Question 1: I usually hate to answer such question. Specially this one. Because I can't measure my Java skills. Since measuring is done w.r.t some reference frame. With which reference I measure my XYZ skills?
Plz. Correct me where I am wrong.

Bye,
Viki.
[ November 08, 2003: Message edited by: Vikrama Sanjeeva ]

Count the flowers of your garden, NOT the leafs which falls away!
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Anish Shar
Greenhorn

Joined: Nov 10, 2003
Posts: 4
Regarding java questions, recently I got asked a bunch of them
1-" difference between java.util.date and java.sql.date"
still have not figured it out
2- vectors and array list - which should be used and where
vectors are synchonized so unless we need them, we should just make do with array list


-<br />everybody makes a mistake, some just dont ever learn!!
Anish Shar
Greenhorn

Joined: Nov 10, 2003
Posts: 4
Folks,
got the naming right now, forgive a green horn :-)
HS Thomas
Ranch Hand

Joined: May 15, 2002
Posts: 3404
Vectors are *not* de rigeur since Java 1.4
ArrayList has better performance. Other reasons are safer processing I think. Of the other collection types - Vectors,Hashtables and HashMaps , HashMaps performed the worst.

regards
[ November 10, 2003: Message edited by: HS Thomas ]
D. Rose
Ranch Hand

Joined: Apr 25, 2003
Posts: 215
I got some of the following
1.What is static and dynamic binding?
2.What parts in java are static bound and dynamic bound?
3.How does JVM achieve synchronization?
Tony Collins
Ranch Hand

Joined: Jul 03, 2003
Posts: 435
What's the difference between a abstract class and an interface ?

Tony
Light Wan
Ranch Hand

Joined: May 15, 2002
Posts: 31
1. Functionality of interface in JAVA.
2. Difference between class String and StringBuffer.
3. Illustrate two or three Design Patterns, why and how to use them.
My answers
1.
  • Implement multi-inheritance
  • Separate the implementation
  • Easy to extend implementation
  • 2.
  • The content of a String object cannot be changed, but that of StringBuffer can.
  • Performance of using StringBuffer is good.
  • 3.
  • MVC, used in GUI design and web design.
  • Adapter, class adapter and object adapter.
  • Factory, encapsulate the implementation and easy to extend implementation

  • Light
    [ November 12, 2003: Message edited by: Light Wan ]

    SCJP2
    Ray Beaumont
    Greenhorn

    Joined: Nov 25, 2003
    Posts: 8
    Originally posted by Rei Damle:
    I got some of the following
    1.What is static and dynamic binding?
    2.What parts in java are static bound and dynamic bound?
    3.How does JVM achieve synchronization?


    What's the answer to those then?
    merlin bar
    Ranch Hand

    Joined: Feb 16, 2003
    Posts: 54
    This is the layout of the last interview I was at:
    First 5 questions were simple eg how do you execute a java command
    a javah
    b javac
    c run
    d start
    e java
    Then some tricky ones.

    The above will compile. This wont though

    Nothing on inheritance. All questions had 7 lines of code or less.
    - 5 & 2 = ?
    - 5 && 2 = ?
    - z = 6
    y = 4;
    y = --z;
    what is the value of y and z now?
    - same as above with z-- instead of --z;
    - One tricky question where the conditions of the code are never met eg:
    x = 2;
    if ( x < 0)
    x++;
    x = ?

    - Define polymorphism
    - " inheritance
    - " encapsulation
    - what is http
    - " ftp
    - " a server
    - " application server
    - what is a Proxy Server'
    - What iis a java bean


    Regards,<br /> merlin_bar
    Jeroen Wenting
    Ranch Hand

    Joined: Oct 12, 2000
    Posts: 5093
    when can you start?
    Indeed during my latest (and last) interview that was the most relevant question asked.
    I make sure my CV tells my work experience in sufficient detail that the technologies used can be derived from that.
    The interview was more about the backgrounds of those projects, the structure of the teams etc.
    I think they'd already decided I had the skills needed based on my CV and just needed to get to know the person.


    42
    Garry Bor
    Greenhorn

    Joined: Jun 06, 2003
    Posts: 15
    Slightly out of topic here but this thread reminds me of a really funny question my friend was asked.
    "How many EJBs can you write in a day?"
    I am still figuring out a good answer to it.


    Garry Bor<br />Singapore
     
    Don't get me started about those stupid light bulbs.
     
    subject: what are the most common questions on Java job interviews?