Do you meet the following criteria? If yes, send your resume asap to sridhar@interviewmantra.net

• Possess 2 to 5 years of IT Experience.
• Education – BE or MCA.
• Programming experience in C/C++/ Java (Swings, Servlets, JSP, strong OO skills).
• Knowledge of Teamcenter ITK programming is a huge advantage.

Note that this requirement is for Indian National only.

These questions were compiled by Rakesh Kumar Vashisht

Java Questions:

1. Where and why do we use the synchronized keyword?
2. Give an example of polymorphism in java with code?
3. What are the classes and interfaces used in Collection framework, briefly explain them?
4. What are inner classes and why do we need them?
5. Do we name the java file using the Outer class’s name?
6. How to access the inner class?
7. Why do we need an abstract class from design perspective?
8. Difference between keywords and variables?
9. What is the deployment process of your application?
10. Explain MVC?
11. What are the components in your application that correspond to Model View and Controller components?
12. Which application server do you use to deploy your app?
13. What database do you use and how do you connect your java application to the database?
14. What is JNDI?
15. What is EJB?
16. What do u mean by serialization? How do we achieve it in java?

Amdocs, Pune is doing a lot of hiring these days. In case you have attended an interview with Amdocs recently, please post the questions that were asked in comments. Let’s share interview questions, experiences and make our lives easier.

Feel free to comment the answers to these questions.

Sun Microsystems is famous for owning the popular Java platform and MySQL database software.

Sun Microsystems, which is already in bad shape, is subject to more pressure now. Owing to the stock implosion and other factors that are not in favor, Sun microsystems has announced to lay off up to 3,000 employees in the coming months.

Here is an excerpt of a comment posted by a person who claims to be an employee of Sun Microsystems :

Pray for us poor Sun Employees…
Mr. Billionaires, don’t you have a heart?, don’t you have a soul?, don’t you win enough money?
Why do we have to suffer sadness, fear, layoff, over-indebtedness, family break, suicide…?
Are we still pawns, numbers in 2009?
We were proud of Sun Microsystems, we were proud of our Creativity, we were proud of our Team Spirit, we were proud of our Passion.

We were Human Beings….

This brings us back to the old discussion of job security in corporate companies. You may be working for the Sun Microsystems, but you are not an exception of being fired when it comes to business reasons.

Can’t anything be done to this attitude of the rich corporates? Can’t the government intervene and save the employees who work hard for the benefit of the company? Should employees always suffer for these corporate deals?

General Questions:

1. Tell me about yourself?
2. Tell me about the project that you are currently working on?
3. What are the technologies used in your current project?
4. Why did you change your previous company?
5. Do you have any questions? (at the end of the interview)

Java Questions:

1. On a scale of 5, how do you rate yourself in Java?
2. What are the four pillars of Object Oriented Programming (OOPS)?
3. What is Encapsulation?
4. What is Abstraction?
5. What is the difference between Encapsulation and Abstraction?
6. What are access specifiers?
7. Explain each of the access specifiers: public, default, protected and private.
8. Is the default access specifier same as protected?
9. Can I access a default member from inside a Sub class?
10. Can I access a protected member from a Sub class outside the package of its Base class?
11. What is an anonymous class? Can you write code to define an anonymous class?
12. What is the difference between a String and a StringBuffer?
13. What is the output upon execution of the following code snippet?

String a = "Hello";
StringBuffer b = new StringBuffer("Hello");

if(a.equals(b)){
 System.out.println("Inside A");
}
else{
 System.out.println("Inside B")
}

14. How to use a StringTokenizer?
15. What are Collections in Java?
16. What is the difference between a Vector and an ArrayList?
17. Can you write a program that emulates a Linked List in Java without using the class LinkedList?
18. What is a thread in Java?
19. What are the uses of threads?
20. What is a process in Java?

Java EE Questions:

1. Do you know Java EE?
2. On a scale of 5, how do you rate yourself in Java EE?
3. Do you know EJB?
4. What is Life Cycle of a Servlet?
5. What are the methods in the Class GenericServlet?
6. What is the difference between GenericServlet and HttpServlet?

SQL Questions:

1. On a scale of 5, how do you rate yourself in SQL?
2. What is DDL?
3. What is DML?
4. What is the difference between DDL and DML?
5. Assume there is a table by name Employee, that has columns emp_name, emp_id and salary.

Write a query that prints emp_name of the employee earning the maximum salary.

UNIX Questions:

1. On a scale of 5, how do you rate yourself in UNIX?
2. Explain the command mv?
3. Explain the command cp?
4. What is the difference between mv and cp?
5. How to use grep command?
6. What command do you use to see all the processes that are running in UNIX?
7. Do you know shell scripting?

Read 15 more Java interview questions asked in Amdocs.

You may want to

Answer these questions by commenting below

This article demonstrates the creation of an executable jar file. This is a hands-on tutorial, I recommend you to follow the below mentioned steps practically instead of simply reading this tutorial.

Step 1:

Download Source Code (nodalo-src.zip) and Binary Classes (nodalo-bin.zip) of the sample Java Project used in this post. Extract the downloaded archive nodalo-bin.zip to Windows D: Drive (D drive optional, can be extracted to any folder).

The structure of the folder ‘nodalo-bin’ would look like this:

nodalo-bin
     |___com
          |__A.class
          |__B.class
          |__C.class

     |___foo
          |__D.class

There is a root directory ‘nodalo-bin’, which in turn has two directories ‘com’ and ‘foo’. Package com contains classes A.class, B.class, C.class . Package foo contains class D.class .

Class B.class has the main method. Our aim is to create an executable jar file, name it nodalo.jar and run main method in the Java Class B.

Step 2:

Create a jar file nodalo.jar that has the directories com and foo in it.

Browse to the directory named “nodalo-bin” and execute the following command in Command Prompt or Terminal.

D:\nodalo-bin> jar cvf nodalo.jar com foo

This command would create nodalo.jar

To view the contents of this jar file, execute:

D:\nodalo-bin>jar tf nodalo.jar

The following output would be shown:

 META-INF/MANIFEST.MF
 com/
 com/A.class
 com/B.class
 com/C.class
 foo/
 foo/D.class

Note that META-INF folder and the file MANIFEST.MF were created on their own.

Step 3:

To execute this jar file, run command:

D:\nodalo-bin>java -jar nodalo.jar

An error similar to the one below would result in the output:

Failed to load Main-Class manifest attribute from nodalo.jar

Step 4:

This is because java does not know where to look for the main method. So we need to explicitly add a manifest file that tells JVM about the Class that contains main method in this Java project.

Create a new text file, name it mainClass.txt and put the following line of code in it:

Main-Class: com.B

Save mainClass.txt in the nodalo-bin directory. The above line instructs JVM to look for main method in B.class

To merge this Manifest file with the one already existing in nodalo.jar, execute the command:

D:\nodalo-bin> jar cmf mainClass.txt nodalo.jar com foo

Now, try executing the jar again:

D:\nodalo-bin>java -jar nodalo.jar

The above command should result in output:

Inside Class D
Inside Class C
Inside Class B
Inside Class A

Great! We have successfully created an executable jar file. Please comment below, if this tutorial helped you.

Read more about Manifest File in Java.

Apache Ant is a java based build tool. You may read the text instructions for installing ant. You may want to download Apache Ant Software.

To see this presentation in full screen or in a larger view click on the following link: http://docs.google.com/Presentation?id=dg8zg9kx_136cdt3qmgn
Tip: Look for speaker notes of the presentation for detailed description of the slides

Welcome to this presentation on Installation of Java development Kit !. As a beginner in Java, it took me few days to discover the basics of java installation. I prepared this presentation to save reader’s precious time in understanding the setup of jdk, PATH and CLASSPATH variables. Note that the scope of this presentation is J2SE (Java 2 Standard Edition 5.0) only and does not include J2EE(Java 2 Enterprise Edition).
This presentation guides you through the step by step procedure to download and install Java SDK (also called JDK) on a windows machine. After following the steps given in this presentation you would know how to compile and run programs using Java.Java SDK installation is helpful only if you wish to code using java. For running java applications, Java Run time environment (JRE) is sufficient. This presentation would have served its purpose if you are able to run your java programs using command prompt at the end of going through the slides. This presentation also shows the screenshots of all the steps required for installing java development kit on windows.

Agenda of slides:
Slide#2 introduces the reader to Java, JDK and JRE. Also briefs about the difference between JRE and JDK.
Slide#3 shows where to look for the latest download of Java Development Kit 5.0
Slide#4 shows the thumbnail of the downloaded installable file. Also briefs about the contents of JDK kit.
Slide#5 shows the Custom setup step of JDK installation. You can choose the folder where you wish to install JDK in the step shown in the slide.
Slide#6 explains the difference between J2SE and J2EE. Gives a mention about ECLIPSE, world’s favourite IDE for JAVA.
Slide#7 shows the Custom setup step of JRE installation. Also briefs about basic steps of java compilation and execution.
Slide#8 shows the progress screen of JRE setup. Also briefs about jar format in java and the advantages of third party java api’s.
Slide#9 shows the java plugin registration for internet explorer and other browers. Also briefs about Java applets and Java FX.
Slide#10 shows the final screen of installation of java. Also briefs about the significance of PATH and CLASSPATH environment variables.
Slide#11 demonstrates how to modify environment variables in windows. Also briefs about javadoc and other command line tools that come along with java compiler in JDK.
Slide#12 demonstrates how to set PATH and CLASSPATH environment variables for JAVA.
Slide#13 shows how to test javac and java tools on command prompt.
Slide#14 demonstrates how to write a hello world program in java. Also shows how to compile and execute HelloWorld.java

Let me know what you think about this slide so that we can improve it. Contact me at j_sridharr at yahoo dot co dot in. For feedback regarding this blog write to feedback@nodalo.com

Target Audience:
Enterprise Java programmers, beginners in Apache Log4j tool.
Content:
This article illustrates the inheritance concept of the world’s most popular Java Logging Framework, Log4j. This blog posts explains one of the nice features of Log4j that caught my eyes.
Author: Sridhar Jammalamadaka

By the way, Log4j is an opensource tool by Apache software foundation (which means its free!). Log4j is a unanimous choice for a logging framework among developers. Log4j finds its use in stand-alone and web-based applications Java.

A practical example is given below to illustrate this concept. This examples uses files A.java, B.java, C.java, log4j.properties

Inheritance in logging using Log4j
Consider Class A, B, C. Class A is in package com, Class B, C are in package com/foo

/*
************************************************************
Index: com/A.java
************************************************************
*/

package com;
import org.apache.log4j.Logger;
public class A {

 // Give Classname.class as input to getLogger method
 private static Logger logger = Logger.getLogger(A.class);

 public A() {
  logger.info("Inside class A constructor");
  this.aMethod();
 }
 public void aMethod() {
  logger.debug("Inside aMethod()");
 }
}

/*
************************************************************
Index: com/foo/B.java
************************************************************
*/

package com.foo;
import org.apache.log4j.Logger;

public class B {
 private static Logger logger = Logger.getLogger(B.class);
 public B() {
  logger.info("Inside Class B constructor");
  this.bMethod();
 }
 public void bMethod() {
  logger.debug("Inside bMethod()");
 }
}

/*
************************************************************
Index: com/foo/C.java
************************************************************
*/

package com.foo;
import org.apache.log4j.Logger;
import org.apache.log4j.PropertyConfigurator;
import com.A;

public class C {
 private static Logger logger = Logger.getLogger(C.class);
 public C() {
  logger.info("Inside class C constructor");
  this.cMethod();
 }

 public void cMethod() {
  logger.debug("Inside cMethod()");
 }

 public static void main(String args[]) {
  PropertyConfigurator.configure("log4j.properties");
  A a = new A();
  B b = new B();
  C c = new C();
 }
}

Index: log4j.properties
=====================================================================
#This sets the rootLogger Level to DEBUG and adds ConsoleAppender
log4j.rootLogger=debug,CONSOLE
############ Settings for CONSOLE Appender #################
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
#Set the Layout for CONSOLE Appender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
#Set the Conversion pattern for printing logs
log4j.appender.CONSOLE.layout.ConversionPattern=%d{HH:mm:ss,SSS} %-5p %c – %m%n

Above properties file would configure logging levels in such a way that only debug logs or above would be displayed. The logs are configured to be shown on the console or command prompt where this java program is run.

Output would be:

  18:19:01,854 INFO com.A - Inside class A constructor
  18:19:01,854 DEBUG com.A - Inside aMethod()
  18:19:01,870 INFO com.foo.B - Inside Class B constructor
  18:19:01,870 DEBUG com.foo.B - Inside bMethod()
  18:19:01,870 INFO com.foo.C - Inside class C constructor
  18:19:01,870 DEBUG com.foo.C - Inside cMethod()

If we add a line of code to our log4j.properties
log4j.logger.com.foo=off

Logging is switched off in all the classes contained in the package, com.foo, i.e., Class B, Class C . This simply means that all the log statements written in classes B, C would not appear in the output.

Output would be:

  18:23:37,478 INFO com.A - Inside class A constructor
  18:23:37,478 DEBUG com.A - Inside aMethod()

Let us say we added below code snippet instead of the previous one mentioned to our log4j.properties
log4j.logger.com=off

Let us see what the output is. Hey there is no log statement at all! We switched off logging of package com right?
Which means logging should be switched off only in the classes directly under com folder , i.e, Class A

But why did logging in Class B, Class C which fall under package com.foo also get turned off??

Now this is the inheritance concept in Log4j. Until explicitly specified not to allow inheritance, the logging properties set to a package folder would apply to all the sub packages under it. So, the logging properties applied to com package would be inherited to com.foo package too.

I hope this tutorial was of some use to you and it did not confuse you further, please comment below your feedback.

Next Steps: Download Log4j, Learn how to use Log4j

1. Why JAVA?
2. What is JAVA?
3. What are the versions of JAVA, Which one of them should I learn?
4. How do I learn JAVA?
5. Any extra material to learn JAVA better?
6. How many days would I need to learn JAVA?
7. What should I have already known before learning JAVA?
8. Which topics should I focus on in JAVA 2 Special Edition?
9. What are Certifications in JAVA?
10. How to prepare for SCJP(Sun Certified JAVA professional) certification?
11. What is J2EE now?
12. Give me more details about SCJP

1. Why JAVA?
If you aspire to become a software engineer, learning java is the best thing that you can do. Knowledge in JAVA could fetch you a software job. Or if you already are working in a software company, it would give you an edge over others. It would help new joinees clear the initial training programmes conducted at the company.
Back to top

2. What is JAVA?
It is a programming language used for developing web-based and stand-alone applications. You can think of it as a tool to develop all the graphical user stuff like buttons, drop downs and menus and interactive stuff on the web. It is a hot technology that is very much in demand in the current IT market. You must have noticed internet pages ending with .jsp . They are Java Server Pages. So next time when you see jsp on page address, you know that the website uses JAVA technology.
Java transformed the web and created waves. It came to existance in 1995. It was made to support embedded systems. It was not succesful in embedded systems but it attracted a growing World wide web. You must have heard some rumours that JAVA may die soon, but owing to its features and object oriented concepts, JAVA is here to stay.
Back to top

3. What are the versions of JAVA, Which one of them should I learn?
Java Standard EditionJava Enterprise EditionJava Mobile EditionJava FX
As a beginner you are concerned only about JAVA standard edition. Even in that there are many versions such as
J2SE 6.0
J2SE 5.0
J2SE 1.4.2
J2SE 1.3.1

J2SE 6.0 is the latest one, but as a beginner I would recommend you to start with J2SE 1.4.2 which is the most widely used one.
Back to top

4. How do I learn JAVA?
I recommend you to join a long term Sun certified computer institute that teaches Java (NIIT /SSI if you are in india). For all those wondering what is Sun doing here, Sun Microsystems is the organisation behind Java platform. They develop Java and put it on web for free download. They earn through the money that comes from certification courses and training. Sun Microsystems offers many certification courses. I will tell in-detail about certifications in the coming questions.
You can even find introduction of JAVA in Sun Microsystems site, which you can easily find by googling, that would only help your learning.
Back to top

5. Any extra material to learn JAVA better?
If you wish to supplement your knowledge that you get from a training institute “after” finishing Core JAVA course, you can read “Thinking in JAVA by Bruce eckel” . This book is NOT for beginners. If you are a beginner, try “Head First Java, Your Brain on Java – A Learner’s Guide” by Bert Bates, Kathy Sierra
Back to top

6. How many days would I need to learn JAVA?
In order to learn the basics of Core Java you would require 3 months and if you take a short term course, I believe it would take 3 weeks to grasp the concepts. If you wish to learn and get SCJP(Sun Certified Java Professional) certification you will need 3-6 months of study and practice.
Back to top

7. What should I have already known before learning JAVA?
You should know well any of the procedural programming lanugages like C language. Acquaintance with Control statements, Syntax of statements and expressions, Scope rules, Functions, call by value, data types in C language is a must.
Knowledge of C++ is a great plus, not mandatory though. In C++, acquaintance with object oriented programming concepts, classes, Inheritance, Overloading concepts would help you learn Java better.
Java is an object oriented language and shares a few similarities with C++. Java is all about classes and objects. So good knowledge of object oriented concepts would help you learn Java a lot quicker.
Back to top

8. Which topics should I focus on in JAVA 2 Special Edition?
Object Oriented conepts: Classes and objects, Interfaces, Inheritance, Abstract classes, access modifiers, data types, variables, static variables, Java Beans naming standards, packages, invoking and using javac compiler, debugging java code, Exceptions, Arrays, Constructors, overloading, String class, Input/Output streams, AWT, basics of swings, applets, collection classes and utilities.
Back to top

9. What are Certifications in JAVA?
Certifications are special online tests conducted by the companies owning any technology. This certifications are words of promise that beholder of that certification would have sound knowledge in that technology. Sun certifications are highly valued in software organisations.

To name few of certifications that Sun MicroSystems has to offer:
SCJA(Sun Certified JAVA Associate)
SCJP(Sun Certified JAVA Programmer)
SCJD(Sun Certified JAVA Developer)

SCJA is too basic and is not valued as much as SCJP. I recommend a beginner to aim for SCJP. SCJD is advanced certification and it is not for beginners. For SCJD you require to have SCJP certification. Few years of experience would make you fit for SCJD.
Back to top

10. How to prepare for SCJP(Sun Certified JAVA professional) certification?
After finishing Core java course in a good computer training institute. Ideally with 3 months of practise and “Sun Certified Java Programmer for JAVA 5 by Kathy sierra and Berty Bates” would be the best book in the market to achieve your goal.
Back to top

11. What is J2EE now?
It is continuation of J2SE . J2EE is used for preparing server pages where as J2SE is used for preparing client pages and applications. There is Sun Certified Web Component Developer (SCWCD)) certification for J2EE. However you need to be an SCJP before you can write SCWCD.
Back to top

12. More details about SCJP:

SCJP has currently three options : SCJP 6, SCJP 1.5 and SCJP 1.4. SCJP 6 is the latest one added for testing JAVA version 6, I would recommend SCJP 1.5 as java version 6 is very new one, so it may be tough to get coaching or material on that test. There are upgrade exams for those people who wish to upgrade their certification. For example let us say Mr.XYZ is a certified SCJP 1.4 programmer. He wishes to get SCJP 1.5 he need pay as much required for SCJP 1.5. Fee would be less, apart from that syllabus would be less.

Details of Sun Certified Programmer for the Java Platform, Standard Edition 5.0 (CX-310-055) are as follows:

• Delivered at: Authorized Worldwide Prometric Testing Centers (http://www.prometric.com/)
• Exam type: Multiple choice and drag and drop
• Number of questions: 72
• Pass score: 59% (43 of 72 questions)
• Time limit: 175 minutes
• Cost: 200$ (may change see below link for latest price) http://www.sun.com/training/catalog/courses/CX-310-055.xml
• In Indian rupees around 4000. May vary from place to place within India. You can even get discount in some centers.
• Syllabus/Objectives for SCJP 1.5 is available at http://www.sun.com/training/catalog/courses/CX-310-055.xmlAll the best! Help me improve this article. Feel free to comment or mail me at j_sridharr(at)yahoo(dot)co(dot)in

  Back to top