Java/J2EE Job Interview

2012-12-06T23:01:00.000-08:00

Q 01: Give a few reasons for using Java? LF DC

A 01: Java is a fun language. Let's look at some of the reasons:

Built-in support for multi-threading, socket communication, and memory management (automatic garbage collection).
Object Oriented (OO).
Better portability than other languages across operating systems.
Supports Web based applications (Applet, Servlet, and JSP), distributed applications (sockets, RMI. EJB etc)
and network protocols (HTTP, JRMP etc) with the help of extensive standardised APIs (Application Program Interfaces).

Q 02: What is the difference between C++ and Java? LF

A 02: Both C++ and Java use similar syntax and are Object Oriented, but:

Java does not support pointers. Pointers are inherently tricky to use and troublesome.
Java does not support multiple inheritances because it causes more problems than it solves. Instead Java supports multiple interface inheritance, which allows an object to inherit many method signatures from different interfaces with the condition that the inheriting object must implement those inherited methods. The multiple interface inheritance also allows an object to behave polymorphically on those methods. [:)]
Java does not support destructors but rather adds a finalize() method. Finalize methods are invoked by the
garbage collector prior to reclaiming the memory occupied by the object, which has the finalize() method. This means you do not know when the objects are going to be finalized. Avoid using finalize() method to release non-memory resources like file handles, sockets, database connections etc because Java has only a finite number of these resources and you do not know when the garbage collection is going to kick in to release these resources through the finalize() method.
Java does not include structures or unions because the traditional data structures are implemented as an object oriented framework.

Q 03: What are the advantages of Object Oriented Programming Languages (OOPL)?

A 03: The Object Oriented Programming Languages directly represent the real life objects like Car, Jeep, Account,

Customer etc. The features of the OO programming languages like polymorphism, inheritance and

encapsulation make it powerful. [Tip: remember pie which, stands for Polymorphism, Inheritance and

Encapsulation are the 3 pillars of OOPL]

Q 04: How does the Object Oriented approach improve software development? DC

A 04: The key benefits are:

􀂃 Re-use of previous work: using implementation inheritance and object composition.

􀂃 Real mapping to the problem domain: Objects map to real world and represent vehicles, customers,

products etc: with encapsulation.

􀂃 Modular Architecture: Objects, systems, frameworks etc are the building blocks of larger systems.

Java

The increased quality and reduced development time are the by-products of the key benefits discussed above.

If 90% of the new application consists of proven existing components then only the remaining 10% of the code

have to be tested from scratch.

Q 05: What is the difference between an abstract class and an interface and when should you use them?

A 05: In design, you want the base class to present only an interface for its derived classes. This means, you don’t want

anyone to actually instantiate an object of the base class. You only want to upcast to it (implicit upcasting, which

gives you polymorphic behaviour), so that its interface can be used. This is accomplished by making that class

abstract using the abstract keyword. If anyone tries to make an object of an abstract class, the compiler prevents

it.

The interface keyword takes this concept of an abstract class a step further by preventing any method or function

implementation at all. You can only declare a method or function but not provide the implementation. The class,

which is implementing the interface, should provide the actual implementation. The interface is a very useful and

commonly used aspect in OO design, as it provides the separation of interface and implementation and

enables you to:

􀂃 Capture similarities among unrelated classes without artificially forcing a class relationship.

􀂃 Declare methods that one or more classes are expected to implement.

􀂃 Reveal an object's programming interface without revealing its actual implementation.

􀂃 Model multiple interface inheritance in Java, which provides some of the benefits of full on multiple

inheritances, a feature that some object-oriented languages support that allow a class to have more than one

superclass.

Shape

Circle Square

CircleOnSquare

Diamond problem & use of interface

No multiple inheritance in JAVA

Circle Square CircleOnSquare

ShapeIF

CircleIF

SquareIF

Multiple interface inheritance in JAVA

Abstract class Interface

Have executable methods and abstract methods. Have no implementation code. All methods are abstract.

Can only subclass one abstract class.

A class can implement any number of interfaces.

Can have instance variables, constructors and any

visibility: public, private, protected, none (aka package).

Cannot have instance variables, constructors and can have

only public and none (aka package) visibility.

When to use an abstract class?: In case where you want to use implementation inheritance then it is usually

provided by an abstract base class. Abstract classes are excellent candidates inside of application frameworks.

Abstract classes let you define some default behaviour and force subclasses to provide any specific behaviour.

Care should be taken not to overuse implementation inheritance as discussed in Q8 in Java section.

Java

When to use an interface?: For polymorphic interface inheritance, where the client wants to only deal with a type

and does not care about the actual implementation use interfaces. If you need to change your design frequently,

you should prefer using interface to abstract. CO Coding to an interface reduces coupling and interface

inheritance can achieve code reuse with the help of object composition. Another justification for using interfaces

is that they solve the ‘diamond problem’ of traditional multiple inheritance as shown in the figure. Java does not

support multiple inheritances. Java only supports multiple interface inheritance. Interface will solve all the

ambiguities caused by this ‘diamond problem’.

Design pattern: Strategy design pattern lets you swap new algorithms and processes into your program without

altering the objects that use them. Strategy design pattern: Refer Q11 in How would you go about… section.

Maruti Suzuki Ritz My Car

2012-03-05T23:22:00.001-08:00

It was great Expirence to have the Maruti Suzuki Car. Its My first car. 1200cc Petrol car. Love to drive the car on High way. One can get more details on
http://www.carsingh.com/new/Maruti-Suzuki-Ritz.html
Even if you want to compare the Ritz v/s i10 please watch out on
http://in.answers.yahoo.com/question/index?qid=20090809083656AAckW9u
With all the comparison and with latest pics one check it on
http://www.team-bhp.com/forum/test-drives-initial-ownership-reports/63152-comparison-hyundai-i10-1-2-kappa-vs-maruti-ritz-1-2-kb.html

Before buying a car one have take few precosion such as :
1) milage
2) accessories
3) cost
4) to take diseal or petrol

Maruti Ritz is available in both Petrol and diesel version. The petrol version of the car is packed with 1.2 L, 1197 cc K -12 series engine. The K-12 series engine is packed with 5 Speed Manual Transmission Gearbox and BS IV emission. The highly powerful engine of Maruti Ritz offers a maximum power of 85 PS at 6000 rpm and a torque of 113 Nm at 4500 rpm. The diesel version of Maruti Ritz is packed with 1.3L, 1248 cc DDiS engine with 5 Manual Transmission Gearbox that offers greater mileage and acceleration to the car. This DDiS engine is very fuel efficiency and offers an impressive power of 75 PS at 4000 rpm and a torque of 190 Nm at 2000 rpm

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Palwencha

2010-01-21T08:37:00.000-08:00

Hi,I