Java Fundamental-VI

1. What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.


2. What is the difference between the Boolean & operator and the && operator?
- If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.


3. How many times may an object's finalize() method be invoked by the garbage collector?
An object's finalize() method may only be invoked once by the garbage collector.


4. What is the purpose of the finally clause of a try-catch-finally statement?
The finally clause is used to provide the capability to execute code no matter whether or not an exception is thrown or caught.


5. What is the argument type of a program s main() method?
A program's main() method takes an argument of the String[] type.


6. Which Java operator is right associative?
The = operator is right associative.


7. Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.


8. What is the difference between a break statement and a continue statement?
A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.


9. What must a class do to implement an interface?
It must provide all of the methods in the interface and identify the interface in its implements clause.


10. What is the advantage of the event-delegation model over the earlier event-inheritance model?
The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a component s design and its use. The other advantage of the event-delegation model is that it performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to repeatedly process unhandled events, as is the case of the event-inheritance model.

Application Vs. Web Server

(1) Webserver serves pages for viewing in web browser, application server provides exposes businness logic for client applications through various protocols.

(2) Webserver exclusively handles http requests.application server serves bussiness logic to application programs through any number of protocols.

(3) Webserver delegation model is fairly simple,when the request comes into the webserver,it simply passes the request to the program best able to handle it(Server side program). It may not support transactions and database connection pooling.

(4) Application server is more capable of dynamic behaviour than webserver. We can also configure application server to work as a webserver.Simply applic! ation server is a superset of webserver.

(5) Web Server serves static HTML pages  or gifs, jpegs, etc., and can also run code written in CGI, JSP etc. A Web server handles the HTTP protocol. Eg of some web server are IIS or apache.

(6) An Application Server is used to run business logic or dynamically generated presentation code. It can either be .NET based or J2EE based (BEA WebLogic Server, IBM WebSphere, JBoss).

(7) A J2EE application server runs servlets and JSPs (infact a part of the app server called web container is responsible for running servlets and JSPs) that are used to create HTML pages dynamically. In addition, J2EE application server can run EJBs - which are used to execute business logic.

(8) An Application server has a 'built-in' web server, in addition to that it supports other modules or features like e-business integration, independent management and security module, portlets etc.