Skip to main content

Java J2EE Interview Questions and Answers - Part 1

  1. What is the difference between procedural and object-oriented programs?- a) In procedural program, programming logic follows certain procedures and the instructions are executed one after another. In OOP program, unit of program is object, which is nothing but combination of data and code. b) In procedural program, data is exposed to the whole program whereas in OOPs program, it is accessible within the object and which in turn assures the security of the code.
  2. What are Encapsulation, Inheritance and Polymorphism?- Encapsulation is the mechanism that binds together code and data it manipulates and keeps both safe from outside interference and misuse. Inheritance is the process by which one object acquires the properties of another object. Polymorphism is the feature that allows one interface to be used for general class actions.
  3. What is the difference between Assignment and Initialization?- Assignment can be done as many times as desired whereas initialization can be done only once.
  4. What is OOPs?- Object oriented programming organizes a program around its data, i. e. , objects and a set of well defined interfaces to that data. An object-oriented program can be characterized as data controlling access to code.
  5. What are Class, Constructor and Primitive data types?- Class is a template for multiple objects with similar features and it is a blue print for objects. It defines a type of object according to the data the object can hold and the operations the object can perform. Constructor is a special kind of method that determines how an object is initialized when created. Primitive data types are 8 types and they are: byte, short, int, long, float, double, boolean, char.
  6. What is an Object and how do you allocate memory to it?- Object is an instance of a class and it is a software unit that combines a structured set of data with a set of operations for inspecting and manipulating that data. When an object is created using new operator, memory is allocated to it.
  7. What is the difference between constructor and method?- Constructor will be automatically invoked when an object is created whereas method has to be called explicitly.
  8. What are methods and how are they defined?- Methods are functions that operate on instances of classes in which they are defined. Objects can communicate with each other using methods and can call methods in other classes. Method definition has four parts. They are name of the method, type of object or primitive type the method returns, a list of parameters and the body of the method. A method’s signature is a combination of the first three parts mentioned above.
  9. What is the use of bin and lib in JDK?- Bin contains all tools such as javac, appletviewer, awt tool, etc., whereas lib contains API and all packages.
  10. What is casting?- Casting is used to convert the value of one type to another.
  11. How many ways can an argument be passed to a subroutine and explain them?- An argument can be passed in two ways. They are passing by value and passing by reference. Passing by value: This method copies the value of an argument into the formal parameter of the subroutine. Passing by reference: In this method, a reference to an argument (not the value of the argument) is passed to the parameter.
  12. What is the difference between an argument and a parameter?- While defining method, variables passed in the method are called parameters. While using those methods, values passed to those variables are called arguments.
  13. What are different types of access modifiers?- public: Anything declared as public can be accessed from anywhere. private: Anything declared as private can’t be seen outside of its class. protected: Anything declared as protected can be accessed by classes in the same package and subclasses in the other packages. default modifier : Can be accessed only to classes in the same package.
  14. What is final, finalize() and finally?- final : final keyword can be used for class, method and variables. A final class cannot be sub classed and it prevents other programmers from sub classing a secure class to invoke insecure methods. A final method can’t be overridden. A final variable can’t change from its initialized value. finalize() : finalize() method is used just before an object is destroyed and can be called just prior to garbage collection. finally : finally, a key word used in exception handling, creates a block of code that will be executed after a try/catch block has completed and before the code following the try/catch block. The finally block will execute whether or not an exception is thrown. For example, if a method opens a file upon exit, then you will not want the code that closes the file to be bypassed by the exception-handling mechanism. This finally keyword is designed to address this contingency.
  15. What is UNICODE?- Unicode is used for internal representation of characters and strings and it uses 16 bits to represent each other.

Comments

Popular Posts

Openings in HP Inc

Send an email to contactme [at] site4sites.co.in by sending your profile and matching requisition number.

Go through detailed job description at http://www8.hp.com/us/en/jobs/index.html

Requisition NO Job Function City Job Posting Title Management Level 3043232 Business Planning Bangalore Business Planning Analyst 15 Intermediate 3047104 Business Planning Bangalore Supply Chain Planning Consultant 15 Intermediate 3047102 Business Planning Bangalore Supply Chain Planning Consultant 15 Intermediate 3047103 Business Planning

DOT NET Interview Questions with Answers

When not to use Design Patterns?Do not use design patterns in any of the following situations.• When the software being designed would not change with time.• When the requirements of the source code of the application are unique.If any of the above applies in the current software design, there is no need to apply design patterns in the current design and increase unnecessary complexity in the design.When to use Design Patterns?Design Patterns are particularly useful in one of the following scenarios.• When the software application would change in due course of time.• When the application contains source code that involves object creation and event notification.Benefits of Design Patterns:The following are some of the major advantages of using Design Patterns in software development.• Flexibility• Adaptability to change• ReusabilityWhat are Design Patterns?A Design Pattern essentially consists of a problem in a software design and a solution to the same. In Design Patterns each pattern…

Wipro Infotech Walk-in for Freshers: Oct 31

Freshers IT Job Opening at Wipro InfotechExperience: 0 - 1 Years

Location: Pune

Education:
UG - Any Graduate - Any Specialization  
PG - Any PG Course - Any Specialization

Industry Type: IT-Hardware & Networking

Functional Area: IT-Support, Telecom, Hardware
Job Description:
Walk-in on 31st October at  Wipro Limited 5th Floor, C-Wing, Godrej Eternia, Old Pune - Mumbai Road, Near Shopper's Stop, Shivajinagar, Pune

Timings- 10:00am - 4:00pm



Contact person - Deepa Raman

Wipro is looking for candidates with 6 months to 1 year experience who can join immediately. The role will be on direct contract with Wipro.



Skills Required -
* Good communication & grammatical skills
* Basic understanding of networking terminologies
* Knowledge of workflow management tools like Clarify and Remedy would be desired
* Candidate should be willing to work in a 24/7 shift


Desired Candidate Profile
Walk-in on 31st October at Wipro Limited 5th Floor, C-Wing, G…

Student Career Path

A great image which shows student career path. Any person who has completed his 10th or 12th or btech can find his career from this image.





Another Link to download

HP for ITO, PPS, EG, GBS, ESBPO, CSCB & GSD

Job Title 
Requisition Number &
LocationJob DescriptionRefer the below positions through Job SearcherITOSAP BASIS Delivery Lead/project Manager1069661 BangaloreoBachelor of Engineering, 8-12 years of exp in SAP Basis, Minimum of 3 years in delivery.oGood experience in SAP Basis support and implementation. oEXP in migrations, Upgrades, Implementation and Unicode Conversion of single Code Page & MDMP for SAP products.PPS

Java Questions

Just a few interview questions which I faced in the interviews ... the thought of sharing..

 1)What is JVM?
2)What is JDK?
3)What is JRE? Differences between JDK and JRE?
4)How Java is platform independent?
5)When you say java FileName what happens? Every time it creates a new JVM instance or how?
6)What are the benefits/features of java?
7)What are the differences between C# and Java?
8)What are the major properties of java? i.e. Encapsulation, Inheritance, Abstraction and polymorphism. Explain those and give some examples of them.
9)What is the difference between interface and abstract class? Examples of each and when to use what?
10)How the string is immutable? What is immutable? Any other classes in java are immutable?
11)How you can create an immutable class? What happens internally?
12)What are the differences between final, finally and finalize?
13)What are differences between string buffer and string builder and when to use what?
14)Various questions on access modifiers like p…

Contact Form

Name

Email *

Message *