Whether given no. is Armstrong or not

/*Write a program to find whether given no. is Armstrong or not. 

 Example :           Input - 153       

 Output - 1^3 + 5^3 + 3^3 = 153, so it is Armstrong no. */

class Armstrong{

      public static void main(String args[]){

      int num = Integer.parseInt(args[0]);

      int n = num; //use to check at last time

Convert given no. of days into months and days

/* Write a program to convert given no. of days into months and days.

  (Assume that each month is of 30 days)

  Example :         

  Input - 69  

 Output - 69 days = 2 Month and 9 days */

Program to generate a Triangle

/*Write a program to generate a Triangle.

 eg:

  1
  2 2
  3 3 3
  4 4 4 4

 and so on as per user given number */

class Triangle{

      public static void main(String args[]){

Program to Swap the values

/* Write a program to Swap the values */

class Swap{

      public static void main(String args[]){

      int num1 = Integer.parseInt(args[0]);

      int num2 = Integer.parseInt(args[1]);

      System.out.println("\n***Before Swapping***");

      System.out.println("Number 1 : "+num1);

      System.out.println("Number 2 : "+num2);

Program to Display Multiplication Table

/* Program to Display Multiplication Table */

class MultiplicationTable{

      public static void main(String args[]){

      int num = Integer.parseInt(args[0]);

      System.out.println("*****MULTIPLICATION TABLE*****");

Concatenate string using for Loop

/* Write a program to Concatenate  string using for Loop   Example:          Input - 5          Output - 1 2 3 4 5 */

class Join{

      public static void main(String args[]){

      int num = Integer.parseInt(args[0]);

JavaServer Pages

  Java Server Pages (JSP) 

It is a Java technology that allows software developers to dynamically generate HTML, XML or other types of documents in response to a Web client request. The technology allows Java code and certain pre-defined actions to be embedded into static content.

The JSP syntax adds additional XML-like tags, called JSP actions, to be used to invoke built-in functionality. Additionally, the technology allows for the creation of JSP tag libraries that act as extensions to the standard HTML or XML tags. Tag libraries provide a platform independent way of extending the capabilities of a Web server. JSPs are compiled into Java Servlets by a JSP compiler. A JSP compiler may generate a servlet in Java code that is then compiled by the Java compiler, or it may generate byte code for the servlet directly.
"JavaServer Pages" is a technology released by Sun.

Java Servlet

Java Servlet

The Servlet API, contained in the Java package hierarchy javax.servlet, defines the expected interactions of a web container and a servlet. A web container is essentially the component of a web server that interacts with the servlets. The web container is responsible for managing the lifecycle of servlets, mapping a URL to a particular servlet and ensuring that the URL requester has the correct access rights.

A Servlet is an object that receives requests (ServletRequest) and generates a response (ServletResponse) based on the request. The API package javax.servlet.http defines HTTP subclasses of the generic servlet (HttpServlet) request (HttpServletRequest) and response (HttpServletResponse) as well as an (HttpSession) that tracks multiple requests and responses between the web server and a client. Servlets may be packaged in a WAR file as a Web application.

Moreover, servlets can be generated automatically by JavaServer Pages (JSP), or alternately by template engines such as WebMacro. Often servlets are used in conjunction with JSPs in a pattern called "Model 2", which is a flavor of the model-view-controller pattern.

History
The original servlet specification was created by Sun Microsystems (version 1.0 was finalized in June 1997). Starting with version 2.3, the servlet specification was developed under the Java Community Process. JSR 53 defined both the Servlet 2.3 and JavaServer Page 1.2 specifications. JSR 154 specifies the Servlet 2.4 and 2.5 specifications. As of May 10, 2006, the current version of the servlet specification is 2.5.

In his blog on java.net, Sun veteran and GlassFish lead Jim Driscoll details the history of servlet technology. James Gosling first thought of servlets in the early days of Java, but the concept did not become a product until Sun shipped the Java Web Server product. This was before what is now the Java Platform, Enterprise Edition was made into a specification.

Web containers
A Web container is a computer program that runs Web applications. Web containers are also sometimes called Web engines. Like the other Java APIs, different vendors provide their own implementation. Below is a list of some of the free web containers. (Note that 'free' means that commercial use is free. Some of the commercial containers, e.g. Resin and Orion, make ideal development containers and are also free to use in a server environment for non-profit organizations).

Non-commercial web containers



* Java System Application Server is developed by Sun.
* Apache Tomcat (formerly Jakarta Tomcat) is an open source web container available free of charge under the Apache Software License. It is used in the official reference implementation and has a reputation for being stable.
* Jetty
* Jaminid contains a higher abstraction than servlets.
* Enhydra
* jo!
* Winstone supports specification v2.4, has a focus on minimal configuration and the ability to strip the container down to only what you need.
* tjws spec 2.4, small footprint, modular design

Flow control and Exception in java

 Flow Control and Exceptions

   Unreachable statements produce a compile-time error.

while (false) { x = 3; } // won't compile

for (;false;) { x =3; } // won't compile

if (false) {x = 3; } // will compile, to provide the ability to conditionally compile the code.

·         Local variables already declared in an enclosing block, therefore visible in a nested block cannot be re-declared inside the nested block.

·         A local variable in a block may be re-declared in another local block, if the blocks are disjoint.

·         Method parameters cannot be re-declared.

1.        Loop constructs