What is a Servlet?

Answer: Servlets are modules of Java code that run in a server application (hence the name “Servlets”, similar to “Applets” on the client side) to answer client requests.

Question2:

What advantages does CMOS have over TTL(transitor transitor logic)? (ALCATEL)

Answer:

• low power dissipation
• pulls up to rail
• easy to interface

How is Java unlike C++? (Asked by Sun)

Answer:

Some language features of C++ have been removed. String manipulations in Java do not allow for buffer overflows and other typical attacks. OS-specific calls are not advised, but you can still call native methods. Everything is a class in Java. Everything is compiled to Java bytecode, not executable (although that is possible with compiler tools).

Question4:

What is HTML (Hypertext Markup Language)?

Answer:

HTML (HyperText Markup Language) is the set of “markup” symbols or tags inserted in a file intended for display on a World Wide Web browser. The markup tells the Web browser how to display a Web page’s words and images for the user.

Question5:

Define class.

Answer: A class describes a set of properties (primitives and objects) and behaviors (methods).

Q:In Java, what is the difference between an Interface and an Abstract class?

A: An Abstract class declares have at least one instance method that is declared abstract which will be implemented by the subclasses. An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior.

Q: Can you have virtual functions in Java? Yes or No. If yes, then what are virtual functions?

A: Yes, Java class functions are virtual by default. Virtual functions are functions of subclasses that can be invoked from a reference to their superclass. In other words, the functions of the actual object are called when a function is invoked on the reference to that object.

Q:Write a function to reverse a linked list p in C++?

A:

Link* reverse_list(Link* p)

{

if (p == NULL)

return NULL;

Link* h = p;

p = p->next;
h->next = NULL;

while (p != null)
{

Link* t = p->next;

p->next = h;

h = p;

p = t;
}

return h;
}

Q:In C++, what is the usefulness of Virtual destructors?

A:Virtual destructors are neccessary to reclaim memory that were allocated for objects in the class hierarchy. If a pointer to a base class object is deleted, then the compiler guarantees the various subclass destructors are called in reverse order of the object construction chain.

Q:What are mutex and semaphore? What is the difference between them?

A:A mutex is a synchronization object that allows only one process or thread to access a critical code block. A semaphore on the other hand allows one or more processes or threads to access a critial code block. A semaphore is a multiple mutex.

1) What is the purpose of garbage collection in Java, and when is it used?

The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused. A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used.

2) Describe synchronization in respect to multithreading.

With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchonization, it is possible for one thread to modify a shared variable while another thread is in the process of using or updating same shared variable. This usually leads to significant errors.

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3) How is JavaBeans differ from Enterprise JavaBeans?

The JavaBeans architecture is meant to provide a format for general-purpose components. On the other hand, the Enterprise JavaBeans architecture provides a format for highly specialized business logic components.

4) In what ways do design patterns help build better software?

Design patterns helps software developers to reuse successful designs and architectures. It helps them to choose design alternatives that make a system reusuable and avoid alternatives that compromise reusability through proven techniques as design patterns.

5) Describe 3-Tier Architecture in enterprise application development.

In 3-tier architecture, an application is broken up into 3 separate logical layers, each with a well-defined set of interfaces. The presentation layer typically consists of a graphical user interfaces. The business layer consists of the application or business logic, and the data layer contains the data that is needed for the application.

QUESTION: What is a JavaBean? (asked by Lifescan inc)

ANSWER: JavaBeans are reusable software components written in the Java programming language, designed to be manipulated visually by a software develpoment environment, like JBuilder or VisualAge for Java. They are similar to Microsoft’s ActiveX components, but designed to be platform-neutral, running anywhere there is a Java Virtual Machine (JVM).

QUESTION: What are the seven layers(OSI model) of networking? (asked by Caspio.com)

ANSWER: 1.Physical, 2.Data Link, 3.Network, 4.Transport, 5.Session, 6.Presentation and 7.Application Layers.

QUESTION: What are some advantages and disadvantages of Java Sockets? (asked by Arashsoft.com)

ANSWER:
Advantages of Java Sockets:

Sockets are flexible and sufficient. Efficient socket based programming can be easily implemented for general communications.

Sockets cause low network traffic. Unlike HTML forms and CGI scripts that generate and transfer whole web pages for each new request, Java applets can send only necessary updated information.

Disadvantages of Java Sockets:

Security restrictions are sometimes overbearing because a Java applet running in a Web browser is only able to establish connections to the machine where it came from, and to nowhere else on the network

Despite all of the useful and helpful Java features, Socket based communications allows only to send packets of raw data between applications. Both the client-side and server-side have to provide mechanisms to make the data useful in any way.

Since the data formats and protocols remain application specific, the re-use of socket based implementations is limited.

QUESTION: What is the difference between a NULL pointer and a void pointer? (asked by Lifescan inc)

ANSWER: A NULL pointer is a pointer of any type whose value is zero. A void pointer is a pointer to an object of an unknown type, and is guaranteed to have enough bits to hold a pointer to any object. A void pointer is not guaranteed to have enough bits to point to a function (though in general practice it does).

QUESTION: What is encapsulation technique? (asked by Microsoft)

ANSWER: Hiding data within the class and making it available only through the methods. This technique is used to protect your class against accidental changes to fields, which might leave the class in an inconsistent state