class ClassName{...]]>
			Declaring a Class


	
Java Code: 

	
class ClassName{
  ...code...
}
	


 

Declaring a Class with Parent


	
Java Code: 

	
class ClassName extends parentClassName{
  ...code...
}
	


 

Declaring a class with Interface


	
Java Code: 

	
class ClassName implements interface1, interface2, interface3{
   ...code...
}
	


 

Declaring a Class with Fields


	
Java Code: 

	
class ClassName{
  public [type] publicFieldName;
  private [type] privateFieldName;
  private static [type] staticPrivateFieldName;
  ...code...
}
	


 

Declaring a Private Class


	
Java Code: 

	
private Class className{
  ...code...
}
	


 

Declaring a Method


	
Java Code: 

	
public [returnType] methodName(){
  ...code...
}
	


 

Declaring a Method that does Not Return Anything


	
Java Code: 

	
public void methodName(){
  ...code...
}
	


 

Declaring a Method with Parameters


	
Java Code: 

	
public [returnType] methodName( [type] paramVar1, [type] paramVar2){
   ...code...
}
	


 

Declaring a Method with an Array in Parameters


	
Java Code: 

	
public [returnType] methodName( [type][] arrayName){
  ...code...
}
	


 

Declaring a Private Method


	
Java Code: 

	
private [returnType] methodName(){
  ...code...
}
	


 

Declaring a Method with varargs

Varargs is a feature that allows an undefined amount of parameters to be passed in, and used like an array.  It must be the last item in the parameter list.


	
Java Code: 

	
public [returnType] methodName( [type]... varName ){
   ...code...
}
	


 

Method Signature


	
Java Code: 

	
methodName( [type] paramVar1, [type] paramVar2 )
	


 

Method Overloading

Java is able to distinguish between several methods with the same name based upon what is called in the parameter list.  However, it does NOT differentiate different methods based on its return type.


	
Java Code: 

	
public class ClassName{
  ...fields...

  public void methodName( String s ){
    ...code...
  }
  public void methodName( int i ){
    ...code...
  }
  public void methodName( double d ){
    ...code...
  }
  public void methodName( boolean b ){
    ...code...
  }
  public void methodName( String s, int i){
    ...code...
  }
}
	


 

Adding a Constructor to a Class


	
Java Code: 

	
public class ClassName{
  ...fields...

  public ClassName( [type] paramVar1, [type] paramVar2 ){
    fieldName1 = paramVar1;
    fieldName2 = paramVar2;
  }
}
	


 

Adding Multiple Constructors to a Class


	
Java Code: 

	
public class ClassName{
  ...fields...

  public ClassName(){
    fieldName1 = 0;
    fieldName2 = 0;
  }

  public ClassName( [type] paramVar1, [type] paramVar2 ){
    fieldName1 = paramVar1;
    fieldName2 = paramVar2;
  }
}
	


 

Creating a Constructor with Parameters that Shadow Fields

Shadowing fields makes your code difficult to read, and is conventionally only used within Constructors or Methods that set a particular Field.


	
Java Code: 

	
public class ClassName{
  private [type] fieldName1;
  private [type] fieldName2;

  public ClassName( [type] fieldName1, [type] fieldName2 ){
    this.fieldName1 = fieldName1;
    this.fieldName2 = fieldName2;
  }
}
	


 

Calling the Constructor, with Arguments, to Initialize Object


	
Java Code: 

	
ClassName classObject = new ClassName( [value] , [value] );
	


 

Calling the Constructor, with No Arguments, to Initialize Object


	
Java Code: 

	
ClassName classObject = new ClassName();
	


 

]]>
			penguinCoder
			http://www.java-forums.org/blogs/penguincoder/1559-class-method-cheat-sheet.html
		
		
			
			http://www.java-forums.org/blogs/penguincoder/1558-some-basic-technical-terminolgy-cheat-sheet.html
			Wed, 10 Oct 2012 02:08:56 GMT
			Well I just got out of class, and I thought I would do a brain dump of some of the terminology that is utilized in Programming and Computer Science. ...
			Well I just got out of class, and I thought I would do a brain dump of some of the terminology that is utilized in Programming and Computer Science.  This is going to be in more human readable format then most places I have found on the Internet.



Abstract Algorithm Analysis
What is O(N)?

Big O of N, and it is commonly pronounced, is when the run-time of an algorithm is approximately proportional to the size of the data (N), when there are large amounts of data; in the worst case scenario.



What happens when run-time is doubled?

O(1) - Nothing changes

O(logN) - Increases by a constant

O(N) - Doubles

O(NlogN) - Increases by a little more than double

O(N^2) - Quadruples

O(2^N) - Squares





Traditional Procedural Programming VS Object-Orientated Programming
Tradition Procedural Programming

Also called Process-Orientated or Task-Orientated Programming
Focuses on a specific application, and the sequence of steps to accomplish a given task
The code can be optimized for the needs of that application, so it may be more efficient in time and space during run-time
Very difficult to reuse due to it being customized




Object-Orientated Programming

Data-Orientated
Focuses on development of general purpose data management tools to support all possible related applications
Focuses on code reuse
Initial development may take longer, but the ability to reuse existing tools will make future developments much quicker
The generality of these tools may cause them to be less efficient at run-time






Record VS Object
A record contains just data, and has no control over its access and manipulation.

An object contains both data and the code to manipulate that data.  Data can be declared private, using the keyword 'private', restricting access to this data to public methods inside of the class; this is called Data Hiding.  An object also has a constructor method, which combines the task of storage allocation and initialization into one inseperable operation.  It also allows for the separation between 'interface' and 'implementation'.





Instance VS Class
The best analogy of these two are cookies.  The class would be considered the cookie cutter, where the instance would be considered the actual cookie.

An instance is one specific example of an object.  It has both values and storage allocated to it.

A class is a template/model for an object.  A class defines a new variable type, and therefore does not have either a value or storage allocated to it.  It is initialized using the keyword 'new'.





Static Data Members VS Non-Static Data Members
A static data member is shared by all members of that class.  It is allocated storage in the Static Space, alongside the code.  The lifetime of a static data member is throughout the entire program's execution.  It can be accessed inside or outside of a method, through the use of the class name.

A non-static data member, also called an instance variable, is unique for each instance.  It is allocated storage in the Heap Space, and the lifetime of a non-static variable is from the initialization, use of the keyword 'new', to the point when there are no more references to the instance that it is associated with; and the garbage collector has been run.  It cannot be accessed through static member functions.

They both are defined inside of a class, but outside of any method.  They also both have the same visibility, although it is dependent upon their privacy qualifier.  If they are defined using the keyword 'public', they can be accessed from anywhere.  If they are defined using the keyword 'private', they can only be accessed by methods in the same class.





Virtual Memory
Static Space

Contains the program code, along with any data members and functions.

Stack Space

Contains local variables.  These locations may be used by one function, and later be reused by another function.

Heap Space

Contains dynamically allocated storage; things that are declared using the keyword 'new'.  Locations are assigned by the run-time memory management system, as requested during execution; then reclaimed during garbage collection if no longer used.





Local Variables
Local variables are defined inside of a method, and are only 'alive' while the method is being executed.  They are allocated storage when the method is executed, and they lose their storage as soon as the method exits.  Their visibility is only the containing block, bound by the closest pair of curly braces ({}).

]]>
			penguinCoder
			http://www.java-forums.org/blogs/penguincoder/1558-some-basic-technical-terminolgy-cheat-sheet.html
		
		
			
			http://www.java-forums.org/blogs/blustar-angel/1557-problem-shopping-cart.html
			Wed, 29 Aug 2012 12:15:32 GMT
			how do i increase the quatity of an item when it is added again and again into my shopping cart table.there is only a button add to cart.there is no...
			how do i increase the quatity of an item when it is added again and again into my shopping cart table.there is only a button add to cart.there is no textfeild for quantitiy.

the code as of now i have retreives the items from database and add it into the shipping cart table.  if i clik on it again and again the same item wil be shown again and again.


	
Java Code: 

	
 DefaultTableModel model = (DefaultTableModel) 
tbl1.getModel();
            DefaultTableModel tm = (DefaultTableModel) 
tbl2.getModel();
            int a = tbl1.getSelectedRow();
            if (a == 0) {
                
                try {
                    Class.forName("java.sql.Driver");
                    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/album", "root", "123");
                    Statement stm = con.createStatement();
                    String sql = "select ALBUMNAME,PRICE FROM albums WHERE ALBUMNAME='twilight' ;";
                    ResultSet res = stm.executeQuery(sql);
                    while (res.next()) {
                        String ALBUMNAME = res.getString("ALBUMNAME");
                        int PRICE = res.getInt ("PRICE");

                        tm.addRow(new Object[]{ALBUMNAME, PRICE});
                    }
                    res.close();
                    con.close();
                    stm.close();
                    


                } catch (Exception e) {
                    JOptionPane.showMessageDialog(null, "error in connectivity");
                }
	


 

]]>
			blustar angel
			http://www.java-forums.org/blogs/blustar-angel/1557-problem-shopping-cart.html
		
		
			
			http://www.java-forums.org/blogs/paul/1556-java-7-equivalent-net-timespan.html
			Sat, 28 Jul 2012 05:03:11 GMT
			---Quote (Originally by .paul.)--- 
i used Dates in this particular case, as they were better suited to the application. 
 
but i also created a java...
			

	

		

			

			
				

					 Originally Posted by .paul.
					
				
				
i used Dates in this particular case, as they were better suited to the application.



but i also created a java TimeSpan class, similar to the .Net Framework TimeSpan class:




	
Java Code: 

	
package javaTimeSpans;

/**
 *
 * @author Paul
 */
public class TimeSpan {
    
    private int _days;
    private int _hours;
    private int _minutes;
    private int _seconds;
    
    public int Days(){
        return this._days;
    }
    public void SetDays(int d){
        this._days = d;
    }
    
    public int Hours(){
        return this._hours;
    }
    public void SetHours(int h){
        this._hours = h;
    }
    
    public int Minutes(){
        return this._minutes;
    }
    public void SetMinutes(int m){
        this._minutes = m;
    }
    
    public int Seconds(){
        return this._seconds;
    }
    public void SetSeconds(int s){
        this._seconds = s;
    }
    
    public TimeSpan(int d, int h, int m, int s){
        this._days = d;
        this._hours = h;
        this._minutes = m;
        this._seconds = s;
    }
    
    public TimeSpan(int h, int m, int s){
        this._days = 0;
        this._hours = h;
        this._minutes = m;
        this._seconds = s;
    }
    
    public Boolean Equals(TimeSpan ts){
        return this.Days() == ts.Days() && this.Hours() == ts.Hours() && this.Minutes() == ts.Minutes() && this.Seconds() == ts.Seconds();
    }
    
    public TimeSpan Add(TimeSpan ts){
        int s = this.Seconds() + ts.Seconds();
        int m = this.Minutes() + ts.Minutes();
        int h = this.Hours() + ts.Hours();
        int d = this.Days() + ts.Days();
        
        if(s > 59){
            s -= 60;
            m += 1;
        }
        if(m > 59){
            m -= 60;
            h += 1;
        }
        if(h > 23){
            h -= 24;
            d += 1;
        }
        
        return new TimeSpan(d,h,m,s);
        
    }
    
    public TimeSpan Subtract(TimeSpan ts){
        int s1 = this.Seconds();
        int m1 = this.Minutes() * 60;
        int h1 = this.Hours() * 60 * 60;
        int d1 = this.Days() * 24 * 60 * 60;
        
        int s2 = ts.Seconds();
        int m2 = ts.Minutes() * 60;
        int h2 = ts.Hours() * 60 * 60;
        int d2 = ts.Days() * 24 * 60 * 60;
        
        int sd = (s1+m1+h1+d1) - (s2+m2+h2+d2);
        
        int d = sd / (int)(24 * 60 * 60);
        sd -= (d * (24 * 60 * 60));
        int h = sd / (int)(60 * 60);
        sd -= (h * (60 * 60));
        int m = sd / 60;
        int s = sd - (m * 60);
        
        return new TimeSpan(d,h,m,s); 
        
    }
    
    public int TotalHours() {
        return (this.Days() * 24) + this.Hours();
    }
    
    public int TotalMinutes() {
        return (((this.Days() * 24) + this.Hours()) * 60) + this.Minutes();
    }
    
    public int TotalSeconds() {
        return (((((this.Days() * 24) + this.Hours()) * 60) + this.Minutes()) * 60) + this.Seconds();
    }
    
    @Override public String toString() {
        if(this.Days() != 0){
            return String.format("%d:%02d:%02d:%02d", this.Days(),this.Hours(),this.Minutes(),this.Seconds());
        }
        else {
            return String.format("%02d:%02d:%02d", this.Hours(),this.Minutes(),this.Seconds());
        }
    }
    
}
	


			
		
	


]]>
			.paul.
			http://www.java-forums.org/blogs/paul/1556-java-7-equivalent-net-timespan.html
		
		
			
			http://www.java-forums.org/blogs/sbutt/1554-xml-encoding-problem.html
			Wed, 11 Jul 2012 08:52:52 GMT
			Hi All, 
       I am trying to embedd an xml response string as CData inside an XML tree. The main XML tree is not in my control to create or change....
			Hi All,

       I am trying to embedd an xml response string as CData inside an XML tree. The main XML tree is not in my control to create or change. I just have a class object where i am just setting the content as String, where the string is my xml.



The problem is when the mail xml tree appears, the content of my xml ( RawProfile ) are not properly encoded.




	
Java Code: 

	
<ns5:PotsdamCache xmlns:ns2="http://schemas.xmlsoap.org/ws/2002/12/secext" xmlns:ns3="http://www.opentravel.org/OTA/2003/05" xmlns:ns4="http://www.opentravel.org/OTA/2002/11" xmlns:ns5="http://www.PotsdamCache.com">
			<ns5:Content>&lt;![CDATA[ & l t ; RawProfile & g t ; & l t ; ROWSET type = &quot;AllLinkedParents&quot;& g t ; & l t ; /ROWSET&gt;&lt;ROWSET type = &quot;AllParents&quot;&gt;&lt;ROWSET type = &quot;organization&quot;&gt;&lt;ROW type = &quot;Raw&quot;&gt;PotsdamInstanceReference [id=546565, type=organization, code=6565, name=KID for BE Requests, parentId=0, linkedParentIds=null]&lt;/ROW&gt;&lt;ROW type = &quot;Name&quot;&gt;KID for BE Requests&lt;/ROW&gt;&lt;ROW type = &quot;Code&quot;&gt;1006565004&lt;/ROW&gt;&lt;ROW type = &quot;Id&quot;&gt;6565&lt;/ROW&gt;&lt;ROW type = &quot;ParentId&quot;&gt;0&lt;/ROW&gt;&lt;/ROWSET&gt;&lt;ROWSET...&lt;/RawProfile&gt;]]&gt;</ns5:Content></ns5:PotsdamCache>
	


 You might not see the encode problem above, since this editor handles it, but i hope you got my point. I ma getting these & l t ; & g t ; signs.





I am simply doing the following




	
Java Code: 

	
potsdamCacheRS.setContent(buildRawProfile(userInstance));
	


 where my buildRawProfile method returns a string of my xml ..."<![CDATA[<RawProfile>"....."</RawProfile>]]>".





I also tried another aproach:




	
Java Code: 

	
  Document doc = parseRawProfile(buildRawProfile(userInstance), false);

	// Add a CDATA section to the root element
	Element element = doc.getDocumentElement();
	CDATASection cdata = doc.createCDATASection(buildRawProfile(userInstance));
	element.appendChild(cdata);

...

// Parses an XML file and returns a DOM document.
  // If validating is true, the contents is validated against the DTD
  // specified in the file.
  public Document parseRawProfile(String rawProfile, boolean validating) {
      try {
          // Create a builder factory
          DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
          factory.setValidating(validating);

          // Create the builder and parse the file
          Document doc = factory.newDocumentBuilder().parse(rawProfile);
          return doc;
      } catch (SAXException e) {
          // A parsing error occurred; the xml input is not valid
    	  log.debug(" A parsing error occurred; the xml input is not valid ");
      } catch (ParserConfigurationException e) {
    	  log.debug(" A parsing configuration error occurred; the xml input is not valid ");
      } catch (IOException e) {
    	  log.debug(" A parsing IOException error occurred; the xml input is not valid ");
      }
      return null;
  }
	


 

But then got this error: 	

	
Java Code: 

	
		<faultstring>javax.ejb.EJBTransactionRolledbackException: org.apache.xerces.jaxp.DocumentBuilderFactoryImpl cannot be cast to javax.xml.parsers.DocumentBuilderFactory</faultstring>
	


 

The last approach, i didn't like so may be if someone could give a simple solution to this encoding problem.



Thanks.

]]>
			sbutt
			http://www.java-forums.org/blogs/sbutt/1554-xml-encoding-problem.html
		
		
			
			http://www.java-forums.org/blogs/web-service/1553-architecture-web-service.html
			Sat, 07 Jul 2012 17:43:09 GMT
			Following diagram explains the architecture of the web servers. 
 
Attachment 3939 (http://www.java-forums.org/attachment.php?attachmentid=3939) 
...
			Following diagram explains the architecture of the web servers.





Web Service Architecture



•	Web Service Discovery: All the web services are discovered with the help of this part by meeting certain requirements and passing filters.  The UDDI which stands for Universal Description, Discovery and Integration handles this part of web services.



•	Web Service Description: All the web services are self describing which is most important and interesting feature. A web service can be described once it is located and it will describe about its operations. This part is handled by the Web Services Description Language (WSDL).



•	Web Service Invocation: The message handling between the web services and calling methods of a web service is called web service invocation. SOAP protocol is used to communicate with a web service.



•	Web Service Transport: The entire message transmission between client and server must be transmitted by some mean. The HTTP protocol is used to do this message transmission.

]]>
			Web Service
			http://www.java-forums.org/blogs/web-service/1553-architecture-web-service.html
		
		
			
			http://www.java-forums.org/blogs/web-service/1552-soap-envelope-element.html
			Sat, 07 Jul 2012 17:40:49 GMT
			The end and the start of the message are indicated by SOAP envelope. The receiver will be informed of the complete message arrival.  When a message...
			The end and the start of the message are indicated by SOAP envelope. The receiver will be informed of the complete message arrival.  When a message is received and processed, it will be informed by the SOAP envelope. So it solved the major problem of informing message processing. So in other words we can say that is a packaging method.



Following points will explain it in more detail:



A root element is the base of SOAP envelop message and it is contained by all the messages.
Only single Body element must be part of the Envelope element.
Every SOAP message must contain the Envelope element.
There should be only one Header element in the Envelope and it should be before the body part of Envelope as a first child.
If the SOAP version is changed, the envelope must change.
The “ENV” namespace is used to specify namespace for SOAP envelope.
The “Envelopeelement” is used to specify the SOAP envelope.
The “optionalencodingStyle” element and namespace name are used to declare SOAP encoding.
The v1.1 and v1.2 messages are not compatible with each other and it will generate a fault on message.

]]>
			Web Service
			http://www.java-forums.org/blogs/web-service/1552-soap-envelope-element.html
		
		
			
			http://www.java-forums.org/blogs/web-service/1551-soap-introduction.html
			Sat, 07 Jul 2012 17:39:49 GMT
			To exchange messages and information between multiple computers, XML based protocol is used which is called SOAP. SOAP is XML based protocol so you...
			To exchange messages and information between multiple computers, XML based protocol is used which is called SOAP. SOAP is XML based protocol so you can say that it is the XML specification application.



Following rules or statements are considered as true for the SOAP.



•	It is a protocol for communication.

•	SOAP stands for Simple Object Access Protocol.

•	It is designed to use internet for all its communication.

•	It has the facility to use HTTP for sending XML messaging.

•	It handles data transportation of web services.

•	A remote procedure may be called using this protocol.

•	It can also be used to send documents.

•	It can also be used for message broadcasting.

•	It is independent of language.

•	It is independent of platform.

•	It is based on XML to send and get information and define how it will be achieved.



SOAP is used in:



•	Different message systems.

•	Transport protocols

•	Remote procedure calls.



The major focus of SOAP is on the remote procedure calls using HTTP. It helps different applications to connect and method calling remotely.

]]>
			Web Service
			http://www.java-forums.org/blogs/web-service/1551-soap-introduction.html
		
		
			
			http://www.java-forums.org/blogs/log4j/1550-log4j-support-objects.html
			Sat, 07 Jul 2012 17:37:56 GMT
			Following are the log4j framework important support objects which are critical in this framework. 
 
*•	Level Object:* This object is used to define...
			Following are the log4j framework important support objects which are critical in this framework.



•	Level Object: This object is used to define priority of log information. Following log levels are defined in the log4j API:

o	INFO

o	DEBUG

o	ERROR

o	OFF

o	FATAL

o	WARN

o	ALL


•	Filet Object: This object is used to filter and analyze the logging information. Based on the analysis and filter criteria, logging information is logged. Multiple filter objects are attached with the appended object. All these associated filter objects with the appender object must pass the log information so that it can be published. 



•	ObjectRenderer: The logging framework gets different objects string representations using this ObjectRenderer object. The Laout objects used this ObjectRenderer object to arrange log information.



•	LogManager: The LogManager reads the configuration parameters at the startup from a class of file and manage loging framework.

]]>
			Log4j
			http://www.java-forums.org/blogs/log4j/1550-log4j-support-objects.html
		
		
			
			http://www.java-forums.org/blogs/log4j/1549-log4j-core-objects.html
			Sat, 07 Jul 2012 17:36:26 GMT
			Following are the log4j framework important core objects which are important and play a critical role in this framework. 
 
*•	Logger Object:* The...
			Following are the log4j framework important core objects which are important and play a critical role in this framework.



•	Logger Object: The Logger object is provided by the top Logger layer. All the information captured by this Logger Object is stored in a hierarchy and this is the main object responsible for collecting all information.



•	Layout Object: The Layout Object is responsible for formatting all the information in multiple styles. The Layout Objects helps the applender objects in publishing logs. The Layout Objects make the logging information in easy and understandable format.



•	Appender Object: The Appender Object is at the low lever and is used to publish logs. It is used to publish log information to following destinations:

o	File

o	Database

o	Unix Syslog

o	Console


log4j - Core Objects

]]>
			Log4j
			http://www.java-forums.org/blogs/log4j/1549-log4j-core-objects.html
		
		
			
			http://www.java-forums.org/blogs/log4j/1548-log4j-introduction.html
			Sat, 07 Jul 2012 17:34:30 GMT
			Log4J is a Java based API that provides a logging framework which is: 
 
•	Fast 
•	Reliable 
•	Flexible 
 
The Apache software License provides the...
			Log4J is a Java based API that provides a logging framework which is:



•	Fast

•	Reliable

•	Flexible



The Apache software License provides the Log4J distribution. It has been also ported to following different languages:



•	C++

•	C

•	C#

•	Python

•	Eiffel

•	Ruby



Following are the core features and functionalities of Log4J Framework:



•	It is configurable at runtime using files.

•	It defines the log levels and priorities.

•	It supports logging to following:

o	File

o	Database

o	Unix Syslog

o	Console


The Log4J Framework has following 3 major components:



1.	Loggers: The logging information is collected by the loggers.

2.	Appenders: They are responsible for publishing logs on the destinations as defined previously.

3.	Layouts: They are used for log formatting.





Following are the advantages of logging:



•	The software development considers the loggings as its integral part.

•	It supports fast debugging and tracking of issues.

•	It supports structured and maintainable information storage.



Following are the disadvantages of logging:



•	Slow down the application processing in some cases.

]]>
			Log4j
			http://www.java-forums.org/blogs/log4j/1548-log4j-introduction.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1547-what-major-servlets-tasks.html
			Sat, 07 Jul 2012 17:31:55 GMT
			Following are the major servlets tasks: 
 
•	The Servlet major task is to read client data that is explicitly sent. It may include: 
o	Data sent by a...
			Following are the major servlets tasks:



•	The Servlet major task is to read client data that is explicitly sent. It may include:

o	Data sent by a web page in form of HTML form

o	Data sent by an applet

o	Data sent by some HTTP client


•	The Servlet major task is to read client data that is implicitly sent. It may include:

o	Media types

o	Cookies

o	Different compression


•	The servlet is responsible for data processing and results are produced on processed data. These processes may include:

o	RMI execution

o	Database communication

o	Calling a web service

o	Call a CORBA

o	A direct response is computed


•	The servlet is responsilble for sending following type of explicit data to its clients:

o	Binary – GIF images

o	Text – HTML/XML

o	Excel


•	The servlet is responsible for sending responses to its clients. This process may include following:

o	Type of document is informed to client.

o	Caching parameters

o	Cookies Handling

]]>
			JSP
			http://www.java-forums.org/blogs/jsp/1547-what-major-servlets-tasks.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1546-exception-handling-jsp.html
			Sat, 07 Jul 2012 17:30:40 GMT
			There is always a probability of programming errors in the code while a programmer is coding a JSP page. Following are the major types of errors...
			There is always a probability of programming errors in the code while a programmer is coding a JSP page. Following are the major types of errors which may arise in a JSP code:



•	Checked Exceptions: The checked exception is an unforeseen error by the programmer of JSP code or it is a user error in the code. For example, you are opening a file which may not exisit or may have some issue will raise an exception. At the compile time, these checked exceptions cannot be ignored.



•	Runtime Exceptions: The runtime exceptions occur at the time of program execution and may be avoided by the programmer. As compred to checked exceptions, these exceptions are ignored or not caught by the compile while program is being compiled.



•	Errors: These are uncontroable issue which a user or program cannot handle either at compile time or runtime and they are totally different from exceptions. You usually cannot find the errors in your code like a stack overflow. Also compiler cannot trace these errors at compile time.

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			http://www.java-forums.org/blogs/jsp/1546-exception-handling-jsp.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1545-hits-counter-jsp-page.html
			Sat, 07 Jul 2012 17:29:45 GMT
			You have a website developed in JSP with different pages. The hit counter will help you the total number of users visit your any JSP page.  In most...
			You have a website developed in JSP with different pages. The hit counter will help you the total number of users visit your any JSP page.  In most cases, the hit counter is attached with “index.jsp” page. It is the main login page and most users will first visit this page before navigating to any other page on your application or website. 



The following methods are used to implement hit counter.  These methods are attached with you “Application” object.



•	setAttribute()

•	getAttribute()



The Application object is available in a JSP page and the Application object is created at JSP page initialization. It is destroyed when jspDestroy() method is called at the end of JSP page execution. 



To set an attribute at application level, following piece of code is used:


	
Java Code: 

	
application.setAttribute(String key, Object Value);
	


 The above setAttribute() method can be used to set the hit counter value and it is also used to reset the counter. 



Following piece of code is used to read the value.


	
Java Code: 

	
application.getAttribute(String Key);
	


 Use the above 2 methods to read and increment the counter value whenever a user visit your JSP page.

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			JSP
			http://www.java-forums.org/blogs/jsp/1545-hits-counter-jsp-page.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1544-session-tracking-jsp-page.html
			Sat, 07 Jul 2012 17:12:27 GMT
			JSP communicates with the clients using stateless HTTP protocol. For each new request, following operations are performed: 
 
•	A new connection is...
			JSP communicates with the clients using stateless HTTP protocol. For each new request, following operations are performed:



•	A new connection is opened with web server.

•	Server does not record client information.



In this topic, we will focus on the different ways of handling and maintaining session information. Following are the 3 main ways for session maintaining.



•	Cookies: A cookies also known as session ID is assigned to a web client by the webserver for first request. Next time this session ID is used to recognize the client and maintain a session. There are cases in which web browser does not support cookies so it is not a recommended way of maintaining session.



•	Hidden Fields: Session can be maintained between client and webserver using hidden form fields. These hidden fields are automatically included with the form data and a unique value is communicated between client and server for session handling. This is a recommended approach for maintaining session but in case of hyper link click, it will not send the hidden fields so it’s hard to maintain session in such cases.



•	URL Rewriting: The session information can be appended at the end of of URL. It is a recommended way of maintaining sessions and it will also work for those browsers which do no support cookies.

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			JSP
			http://www.java-forums.org/blogs/jsp/1544-session-tracking-jsp-page.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1543-form-processing-jsp.html
			Sat, 07 Jul 2012 17:10:22 GMT
			In a JSP progam, a programmer may have handled situations in which he sends information from browser to server and finally this information is...
			In a JSP progam, a programmer may have handled situations in which he sends information from browser to server and finally this information is communicated to backend business logic. Following two methods are used by the web browsers to send form data and information to web server.



•	GET Method: The encoded information is sent from browser to the server using this GET method. The information and page URL is separated using the “?” character. Following is an example of GET method information passing.

http://www.java-forums.com/test?key=value

To communicate information between client and web server, GET method is used as the default method. It will generate a long key value string and it will appear in your browser. This is not the recommended way of communication in case of sensitive information like passwords. Also this method has a limit of 1024 characters. 



•	POST Method: The post method is consideres as a reliable and most recommended way of communication between client and web server. The POST method sends all the information and data as a separate message istead of sending it in the URL like GET Method. This message is parsed and used by the backend Java Program as it receives the message in a standard format. The data sent by this method is handled using getParameter() method.

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			JSP
			http://www.java-forums.org/blogs/jsp/1543-form-processing-jsp.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1542-expressions-jsp.html
			Sat, 07 Jul 2012 17:09:18 GMT
			The expression elements are supported by the JSP Page which: 
 
•	Are based on scripting language 
•	These expressions are evaluated. 
•	These...
			The expression elements are supported by the JSP Page which:



•	Are based on scripting language

•	These expressions are evaluated.

•	These expressions are coverted to a String format

•	These are replaced with the expression elements in the JSP Page.



The expression elements in a JSP page are finally converted to a string so you can use it anywhere in your JSP Page. These expression elements must be valid and follow the Java Language. There is only one restriction that you can terminate a line with seimicolon as we usually do in a Java statement.



Following is an example of your JSP Expression Element:


	
Java Code: 

	
<%= your expression %>
	


 Also you can write the above expression element in following XML supported format:


	
Java Code: 

	
<jsp:expression>
	Your expression
</jsp:expression>
	


 The below code represents and example of JSP Expression.


	
Java Code: 

	
<html> 
<body>
   Date: <%= (new java.util.Date()).toLocaleString()%>
</body> 
</html>
	


 

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			JSP
			http://www.java-forums.org/blogs/jsp/1542-expressions-jsp.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1541-how-jsp-page-processed.html
			Sat, 07 Jul 2012 17:07:19 GMT
			In this topic, we will dicuss how a JSP Pages is created and processed by a web server. Following steps will explain it in more detail. 
 
•	An HTTP...
			In this topic, we will dicuss how a JSP Pages is created and processed by a web server. Following steps will explain it in more detail.



•	An HTTP request is sent to the web server by your JSP Page.

•	The web server is responsible for receiving this JSP Page request and it will determine that it’s a JSP request so it will call the JSP engine. This process is done for the pages that have a .jsp extension.

•	The requested JSP page will be loaded from the disk and the JSP engine will convert it into a servlet. It is a simple conversion where:

o	HTML text and converted and print statements are created using this HTML text.

o	All the expressions are converted into proper Java code by the JSP engine.
•	The generated servlet is finally compiled and converted into a class. This class is then forwarded to servlet engine.

•	Finally, this class is loaded and executed by the servlet engine. In the servlet execution process, HTML output is generated which is passed to web server.

•	The web server is responsible for sending this HTML output back to the web client.

•	As a last step, web browser handles the HTML output and renders it on the web page.



JSP Page Processing

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			JSP
			http://www.java-forums.org/blogs/jsp/1541-how-jsp-page-processed.html
		
		
			
			http://www.java-forums.org/blogs/jsp/1540-what-advantages-jsp.html
			Sat, 07 Jul 2012 17:05:04 GMT
			JSP offers the following advantages as compared to using other technologies in the market. 
 
•	*JSP vs Active Server Pages:* The major benefit...
			JSP offers the following advantages as compared to using other technologies in the market.



•	JSP vs Active Server Pages: The major benefit offered by the JSP as compared to Active Server Pages is that it uses Java for expression writing which is more helpful, powerful and easy to use. Where as in Active Server Pages, you will need to use Visual Basic or any other Microsoft language. The second benefit offered by the JSP is that you can port it to any other operating system.



•	JSP vs Pure Servlets: In the servlets, you have to write the entire html in println statements which is hard to format, hard to understand and manage. JSP offers HTML writing in a simple file which is easy to manage.



•	JSP vs Server Side Includes: Server Side Includes is not designed for real programs and it is used for simple inclusions. So it does not support database connections and other functionality.



•	JSP vs JavaScript: JavaScript is used to generate dynamic HTML content on the client end and for other scripting functionality. On the other hand it does not provide server interaction, database access, image processing etc.



•	JSP vs Static HTML: Static HTML is used to just render output on the browser and it does not provide dynamic information.

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			JSP
			http://www.java-forums.org/blogs/jsp/1540-what-advantages-jsp.html