use JSTL with JSP and Struts with example code

Generic tasks such as iteration, conditional processing, data  formatting, internationalization, XML manipulation, and data access are made easy for JSP developers by  JavaServer Pages Standard Tag Library (JSTL ) which includes  a variety  of  tags . Now JSP developers can make use of   JSTL  tags which is  a good alternative to  scriptlets and  JSTL expression language (EL)  which  simplifies  the access to the java language .Two jar files (jstl.jar and standard.jar) are required to make use of JSTL . Now let us download the jar files required to use the tags and EL


There may be  confusion where to download  the two jar files (JSTL.jar and Standard.jar)   which contains various JSTL tag handler classes and .tld files . I am providing the  exact location to download the above two files.

You can download the Standard.jar file  from the location  http://repo2.maven.org/maven2/taglibs/standard/1.1.2/   and click on  the file  standard-1.1.2.jar  to save into local system . You can download the jstl.jar

 file  from the location  http://repo2.maven.org/maven2/javax/servlet/jstl/1.2/  and click on  the file  jstl-1.2.jar   to save into local system. jstl-1.2.jar and  standard-1.1.2. are compatible with Java EE 5 / JSP 2.1.

To check your JSP  ,Java , servlet and  server version which you are using , you can visit my earier post JSP / Java / Server version
 Old versions of jstl & standard jars  can be download   from   http://search.maven.org/#browse%7C2056229056 and http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22taglibs%22%20AND%20a%3A%22standard%22 respectively

Now let us see how to use the JSTL tags in JSP either using struts or without using struts. Steps to follow

1. Download the two jar files from the above location
 2. Put the two jar files into the Web application's library directory (/WEB-INF/lib)
 3. Make a Reference of the Tag Library Descriptors (TLD file) in the JSP .
              Two ways are there to make reference between your JSP pages and the tag library
  i) Make use of  an absolute URI for core library which is used for iteration , condtional processing , etc .. in the JSP as given below

  <%@ taglib uri='http://java.sun.com/jstl/core' prefix='c'%>

  When you use value attribute to accept any expression  like   <c:out value="${country}"/>  , if you get the error  according to TLD or attribute directive in tag file, attribute value does


not accept any expressions , you can use the following URIs instead of above URI.

   <%@ taglib uri='http://java.sun.com/jsp/jstl/core' prefix='c'%>  OR


   <%@ taglib uri='http://java.sun.com/jstl/core_rt' prefix='c'%>

   For more detail on  why the above error occurs and how to solve , you can go through , Solution for attribute value does not accept any expressions
  Similarly , for XML library which is used for XML Processing ,  you can use the following absolute URI

             <%@ taglib uri="http://java.sun.com/jstl/xml"  prefix="x"%>  
                        OR
       <%@ taglib uri="http://java.sun.com/jstl/xml_rt"  prefix="x"%>

                        OR

      <%@ taglib uri="http://java.sun.com/jsp/jstl/xml" prefix="x"%>

  for SQL library (prefix : sql)   which is used for data access
           
               <%@ taglib uri="http://java.sun.com/jstl/xml"  prefix="sql"%> 
                         OR
            <%@ taglib uri="http://java.sun.com/jstl/sql_rt"  prefix="sql"%>
                         OR
             <%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql"%>

  and for format library  (prefix : fmt) which helps for localization  , the following URI is used in the JSP

             <%@ taglib uri="http://java.sun.com/jstl/fmt"  prefix="fmt"%>
                       OR
            <%@ taglib uri="http://java.sun.com/jstl/fmt_rt"  prefix="fmt"%>
                      OR
             <%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%>

 ii) Copy the necessary .tld files like  c.tld , x.tld , sql.tld etc  to the folder WEB-INF .You can get the .tld files in the folder META-INF  when you extract the latest jar files
          a)   You can directly add a JSP declaration to any jsp page that needs to use the tag
   <%@ taglib uri="/WEB-INF/c.tld" prefix="c"%>

    OR

            b)  To make a static reference , add the following entry to the web.xml file

  <taglib>
  <taglib-uri>ctld</taglib-uri>
  <taglib-location>/WEB-INF/c.tld</taglib-location>
  </taglib>
         then you can add the following JSP declaration to any jsp page   <%@ taglib uri="ctld" prefix="c"%> 

Ist method is the preferred one.

Some of the struts  tags are replaced with JSTL tags . You can use struts tags only  when there is no equivalent JSTL tags as  .
 Sample use of JSTL tags

 1.  Example code using struts logic:iterate


  <logic:iterate id="country" collection ="<%=countries%>">
  Country : <%=country%><br> 
  </logic:iterate>  

  the JSTL equivalent code  for the struts  logic:iterate


   <c:forEach var="country" items="${countries}">
  <LI><c:out value="${country}"/>   </c:forEach> 

 2. <bean:define id="empcode" value ="employeeObj"/>
  
 equivalent JSTL is   <c:set var ="empcode" value="${employeeObj}"/>

Oracle SQL Query for two timestamp difference

Below query where given to Sysdate is between two TimeStamp

to_char(AF_AN_S, 'DDMMYYYY HH24:MI'),      AF_EET,     trim(FT_NAME) as AVT_NAME,     AC_REG,      FLB_PAX,      FLB_INF,     P_NAME,    
P_VNAME,      CLG_ACD_CODE,     P_LTR_CODE,     P_PERS_NR,      P_NR   
from     IBSDBA.MV_ACT_FLIGHT,IBSDBA.MV_AIRCRAFT,
IBSDBA.MV_FL_TYP,    
IBSDBA.MV_FLT_ART,
IBSDBA.MV_FLT_BLNG,IBSDBA.MV_VP_FLIGHT_ASSIGN,     
IBSDBA.MV_CREW_LOG, IBSDBA.MV_PERSONAL    
where      P_OWNER = 'TUI'    
and     CLG_P_PERS_NR = P_PERS_NR   
and     VAS_SEQ = CLG_VAS_SEQ    
and     VAS_AF_ID = AF_ID  
and AF_AB_S between TO_TIMESTAMP ('05.04.2012:03:00:00','DD.MM.YYYY:HH24:MI:SS')
and   TO_TIMESTAMP ('05.04.2012:17:00:00','DD.MM.YYYY:HH24:MI:SS')

Call DB2 SP from Java CallableStatement . CallableStatement in java example

JDBC provides three statement interface which is used to send an SQL statement to the database server.
1. Statement
2. PreparedStatement which extends Statement- You can visit my earlier post for detail on PreparedStatement object and example in DB2
3. CallableStatement which extends PreparedStatement
Vendors of JDBC Driver provide classes that implement the above interfaces. Without a JDBC driver , you cannot create objects based on these interfaces .Database connection is required to to create statement object. This tutorial explains about CallableStatement objects and also how to call a DB2 stored procedure from a java application. Please go through my earlier post on how to create stored procedure in db2 . Stored procedure can be called using the SQL CALL statement in DB2. Now how to call the stored procedures located on the database server from your Java application ? Use CallableStatement interface in java.
CallableStatement object enable you to call and execute stored procedures stored on the database server from your Java application . Three types of JDBC parameters are there . They are IN, OUT, and INOUT
1. IN - parameters used for input . You can set values to IN parameters with the setXXX() methods.
2. OUT - result parameter used for output which returns output value of the stored procedure.
3. INOUT - parameter used for both input and output values parameters
A question mark (?) symbol serves as a placeholder for a parameter. The call to invoke the Stored procedure is written in an JDBC escape syntax that may take the followings forms
1. {call procedure_name[(?, ?, ...)]} - which accepts input parameters but no result parameter
2. {? = call procedure_name[(?, ?, ...)]} which returns a result parameter
3. {call procedure_name} - for no input / output parameters

A CallableStatement can return one or multiple ResultSet objects. Multiple ResultSet objects are handled using operations inherited from Statement. cstmt.getMoreResults(); -used to point to the second or next result set .
Now let us see the steps to create a CallableStatement Object . Before creating it , let us create a stored procedure in DB2 . In our example , I have created two Stored procedures in db2.
Ist Stored Procedure (SP) example : to return all records matching with a given salesman_id and date of sale
input - salesmanid , sales_date
output - result set (salesman_id, salesman, item_name , sales_date, sales_amt)

Stored Procedure for the above problem is given below

   
CREATE PROCEDURE  ItemSalesBy (salesmanid  varchar(5), dateofsale date)     SPECIFIC sp10    DYNAMIC RESULT SETS 1
P1: BEGIN
    DECLARE cursor1 CURSOR WITH RETURN FOR   select salesman_id, (select c.name from salesman c where c.salesman_id=b.salesman_id) SalesMan,  (select a.item_name from item_master a where a.item_code=b.item_code) ItemName, sales_date, sales_amt from salesmantxn b  where b.salesman_id=salesmanid and b.sales_date=dateofsale;
    OPEN cursor1;
END P1
@



We can create and call (execute) the above stored procedure using command line processor (CLP) and through java program.
to create stored procedure using CLP , store above stored procedure in a file . for example salesman.sql . Now run the following commands
db2 connect to test
db2 -td@ -vf salesman.sql
to call the above SP through CLP
db2 call ItemSalesBy('101','2012-02-25') , where 101 is the salesman id , 2012-02-25 is the date of sale
Now let us create and call (execute) the above stored procedure using java program

To create CallableStatement object , the following statements are used
CallableStatement cstmt = null;
cstmt = conn.prepareCall ("{ call ItemSalesBy(?,?)}"); // Callablestatement object to call the stored procedure
where ItemSalesBy is the SP name and two question mark (?,?) is used to pass input parametters. In our example , salesman_id , sales_date . The following java program drops the existing SP named ItemSalesBy and creates the same SP and executes with the given input parameters. The statement ResultSet rs = cstmt.executeQuery(); returns the result set returned by the SP .

   
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Scanner;
public class CSPRS2 {
    static Connection conn;
    public static void main(String[] args) {
    
       try {
              Class.forName("COM.ibm.db2.jdbc.app.DB2Driver");
             } catch (ClassNotFoundException e) {
      e.printStackTrace();
      return; }

 try
        {
               conn = DriverManager.getConnection("jdbc:db2:test");
            }
        catch( Exception e )
        {
            e.printStackTrace();
            System.exit(1);
        }
  //  dropSP(); // to drop procedure if already exists 
    createSP();  // to create stored procedure (SP)
       callSP("101", "2012-02-25"); // to execute SP
    }

    private static void dropSP() {
        String str=null;
        Statement stmt = null;
        try
        {
            stmt = conn.createStatement();
           str="drop procedure ItemSalesBy";
            stmt.executeUpdate (str);
        }
        catch (SQLException e1)
        { e1.printStackTrace();}
       }

    private static void createSP() {
        String strSP=null;
        Statement stmt = null;

      strSP="CREATE PROCEDURE  ItemSalesBy (salesmanid  varchar(5), dateofsale date)  SPECIFIC sp10    DYNAMIC RESULT SETS 1 \n" +
             "P1: BEGIN \n" +
             "DECLARE cursor1 CURSOR WITH RETURN FOR   select salesman_id, (select c.name from salesman c  where c.salesman_id=b.salesman_id) SalesMan,  (select a.item_name from item_master a where a.item_code=b.item_code) ItemName, sales_date, sales_amt from salesmantxn b  where  b.salesman_id=salesmanid and b.sales_date=dateofsale; \n" +
             "OPEN cursor1; \n" +
              "END P1 \n";
        try
        {
            stmt = conn.createStatement();
            stmt.executeUpdate (strSP);
            System.out.println("Stored Procedure created successfully\n");
        }
        catch (SQLException e)
        {
            System.out.println("Error in creating SP: " + e.toString());
            System.exit(1);
        } 
    }

    private static void callSP(String sid, String sdate)
    {
        CallableStatement cstmt = null;
        try
        {
            cstmt = conn.prepareCall ("{ call ItemSalesBy(?,?)}");  // CallableStatement object  to call the stored procedure
            cstmt.setString(1,sid);
            cstmt.setDate(2, java.sql.Date.valueOf(sdate));
            ResultSet rs = cstmt.executeQuery();
            System.out.println("SALESMAN_ID SALESMAN              ITEMNAME      SALES_DATE    SALES_AMT\n");
            System.out.println("----------- ---------------- ------------------- ----------  ------------\n");
            if (rs != null) {
 while (rs.next())
 {
  System.out.println(rs.getInt(1) + "             " + rs.getString(2) + "       " + rs.getString(3) + "      " + rs.getString(4) +"       "+rs.getString(5));
 }
                    }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }
}


Output :

2. to calculate wages for a salesman on a particular date based on sales_amt. wages is calculated with the following formula
wages = total_sales_amt * 0.5 /100 + bonus ; and Rs. 100 bonus is added if the sales_amt >10000 and sales_amt<=200000, Rs. 200 bonus if sales_amt>200000 and sales_amt<=300000 , Rs. 300/- bonus if sales_amt>300000

IN Parameter : salesman_id, Sales_date
OUT parameter : wages

Stored Procedure for the above problem is given below

   
CREATE PROCEDURE wagesCalc(IN salesmanid varchar(5)  ,IN SalesDate date , OUT  wages  double)   LANGUAGE SQL
  BEGIN
DECLARE bonus double;
DECLARE sumsales double;
DECLARE wages_temp double;
    DECLARE cursor1 CURSOR FOR SELECT SUM(SALES_AMT),  SUM(SALES_AMT)*0.5/100 FROM SALESMANTXN where SALESMAN_ID=salesmanid  and SALES_DATE=SalesDate;
      SET bonus= 0;
     OPEN cursor1;
     FETCH FROM cursor1 INTO sumsales, wages_temp;
   
IF (sumsales>300000) THEN
 set bonus=300;
ELSEIF (sumsales>200000 and sumsales<=300000) THEN
 set bonus=300;
ELSEIF (sumsales>100000 and sumsales<=200000) THEN
 set bonus=100;
END IF;
     CLOSE cursor1;
SET wages = wages_temp+ bonus;
 END%



to create above SP using CLP , store above stored procedure in a file . eg. wages.sql . Now run the following commands
db2 connect to test
db2 -td% -vf wages.sql
to call the above SP through CLP
db2 call wagesCalc('101', '2012-02-25', ?) , which returns wages for the saleman_id=101 and sales_date='2012-02-25'
Now let us see how to call (execute) the above stored procedure using java program

        private static void callSP(String sid, String sdate)
    {
          Double wages=0.0;
        CallableStatement cstmt = null;
        try
        {
            cstmt = conn.prepareCall ("{ call wagesCalc(?,?,?)}");  // CallableStatement object  to call the stored procedure
            cstmt.setString(1,sid);
            cstmt.setDate(2, java.sql.Date.valueOf(sdate));
            cstmt.registerOutParameter(3, Types.DOUBLE);
          cstmt.execute();
                      wages  = cstmt.getDouble(3);
               System.out.println("Sales Man Id = " + sid  + " Wages= " + wages);
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }


Output of the above program :
D:\as2\JF5>java CSPRS4
Sales Man Id = 101 Wages= 650.0
In the above program , registerOutParameter(3, Types.DOUBLE); Registers the OUT parameter in ordinal position parameterIndex to the JDBC type sqlType
The execute() returns boolean value . if it returns false means , first result is an update count or there is no result ; true means , the first result is a ResultSet object

check parentheses in a string / expression are balanced using Regex / Stack . Find Brackets are matched or not in JAVA Program

One of the interesting  java program given below  that may be asked in core java interview or the same may be given to   students to solve at practical labs

         Write a java program that reads a string (expression) from standard input and find  whether its parentheses "(" , ")" , brackets "[", "]"  and  Braces "{", "}"    are properly balanced or not.  i.e. Every open parentheses"("  , braces "{" and brackets "["  should have closing  parenthesis  ")" , braces "}" and brackets "]" respectively in the right order .   For example, the  program will give output
   true for the following input
              1.   ((29*12)+(54+22))

               2.  {[()()]()}

               3. ((([]{}))((())))

     and false for the following

               1.  [(]).

                2. ((())))

                3.  ((29*12*([5*5+7]*5)) + ((54+22))

Please assume that , '(' , '{' , '[' are open characters and ')' , '}' , ']'  are closing characters . Let us solve the above problem now.
 .
 Method I :   Best way to solve the above problem is using stack data structure .  As we know , stack is a  storage mechanishm that works on  Last -in-First-Out (LIFO) that means  the last item stored on the stack  is the first one to be removed.  For more on Stack , please visit my earlier tutorial Stack a FIFO data structure

How to solve the above problem using stack ?
    1) Read the input string (expression ) from the keyboard
   2) Create a stack object to accept  character only.
    3. Traverse the input string / expression
         a) If the current character is a open (left )  parenthesis '('  or brace '{'  or bracket '['  then push the corresponding closing (right) character (i.e. ')' , '}' , ']')  to the stack. You can push the open chracters.   I have Pushed the closing charaters to the stack instead of left to  reduce the little bit lines of logic.
         b) If the current character is a closing (right) parenthesis ')'  , brace '}' and bracket ']' ,
                         i)  check for the stack is empty , if it is empty , then the parentheses are not balanced  because there is no open characters for the corresponding closing charaters.
                   ii)  if stack is not empty , then check the current character with top character  (get the top character using peek() )  in the stack . If both are equal, then pop the character from the stack and check for the next character.
  4)  Once the traversal of the expression is completed , check for the stack is empty or not . If stack is empty , then parentheses are balanced otherwise not balanced.

The code is as follows .

import java.util.Stack;

import java.util.Scanner;

public class Parentheses1 {

  public static boolean isBalanced1(String exp)  {

      Stack<Character> stack = new Stack<Character>();

 for (int i=0; i<exp.length(); i++) {

  char c = exp.charAt(i);

  switch (c) {

  case '{' : stack.push('}'); break;

  case '(' : stack.push(')'); break;

  case '[' : stack.push(']'); break;

  case ']' : case ')' : case '}' :

   if (stack.isEmpty())

      return false;

   else   if (stack.peek() == c) {

   stack.pop();

   }

   break;

  default : break;

  }

 }

 return stack.isEmpty();

      }

Some of the other tries to solve the above program.

Method II using Regular expression (Regex)  . You can also try without using regex . I have used very simple  regex .  Steps to solve the above problem  are as follows.

1. Remove all characters like digits , operators, etc  except '(', ')' , '{', '}' , '[' , ']' in the expression.
 2. Replace  every occurrence of  '()' , '{}' , '[]'  in the string  with empty string ("")  (i.e  removal of characters)
 3. Repeat the step 2 ,  until you find that nothing has been replaced .
 4. Now check for the expression  is empty or not. If the string is empty , then  parentheses are perfectly  balanced  , otherwise not.

Code is as follows

public static boolean isBalanced2(String exp)  {

String temp="";

while (exp.trim().length() > 0  )

{

exp=exp.replaceAll("[^\\(\\)\\[\\]\\{\\}]", "") ;

exp=exp.replaceAll("\\(\\)", "");

exp=exp.replaceAll("\\{\\}", "");

exp=exp.replaceAll("\\[\\]", "");

if (exp.trim().equals(temp)) break;

temp=exp;

}

if ( exp.trim().length() ==0) return true;

else {

    System.out.println("Unmatched / Unbalanced characters " + exp);

  return false;

     }

   }

Method III :  Using counter . But this method  is not suitable for all situations .   It just checks , whether the expression has equal number of opening and  closing  parentheses or  brackets or braces and does not check the order. For example, consider the following  expression.
  ([{)}]
 The above expression  has the equal number of opening and closing parentheses / brackets / braces . But it is  not in the right order. The right order may be  ([{}])
 This method may be suitable , if you use either   parentheses or  brackets or  braces in the expression.  eg.   ((()(()()))) . Otherwise  the order should be correct, if you use all .

Steps :
              1. Initialize three counters to 0 , one for parentheses, one for braces , and one for bracket
              2. Traverse the expression by a single  character at a time.
  a) If the current character is '(' , '{' , '[' , then   increment the respective counter by one
  b) If the current character is  ')', '}' , ']' , then decrease one from the respective counter variable.
               3. Check whether all the counters are zero or not. If all counters are having 0 , then the parentheses are balanced  , otherwise not . Please always remember limitation using this method.

 Code is as follows.

public static boolean isBalanced3(String exp)  {

int c1=0, c2=0,c3=0;

 for (int i=0; i<exp.length(); i++) {

  char c = exp.charAt(i);

  switch (c) {

  case '{' : c1++; break;

  case '(' : c2++; break;

  case '[' : c3++; break;

  case '}' : c1--; break;

  case ')' : c2--; break;

  case ']' : c3--; break;

  default : break;

  }

     }

if(c1==0 && c2==0 && c3==0)  return true;

else  return false;

      } 

//Main Method to call the above three methods

public static void main(String[] args) {

Scanner sc=new Scanner(System.in).useDelimiter("\n");;

  

String s = sc.next();

 System.out.println("Balanced checking using stack " + isBalanced1(s));

 System.out.println("Balanced checking using regex " + isBalanced2(s));

 System.out.println("Balanced checking using counter " + isBalanced3(s));

    }

} 

create dynamic HTML in JavaScript | Javascript code to add / remove rows dynamically in a table of HTML

This tutorial covers about how to add or  remove rows  in  a table of a HTML  dynamically  using javascript code .   HTML documets can be easily accessed and manipulated using HTML DOM , which represents an HTML document as a tree-structure.  When a  HTML document is  loaded in a browser window , it  becomes a Document object. Now we can use the Document object  to  access to all HTML elements  (as node objects) in a page, using  any script such as Javacript . Using  Document object ,  we can add or remove  element in the html as we do for  xml,  You can gothrough my earlier post to create xml using DOM .
              Let us see some of the following  HTML DOM properties and methods to access / modify the html documents , before writing the actual  program .

Some DOM properties:

nodeName - returns the name of an element
 nodeValue - returns the value of an element
 parentNode - returns the parent node of an element
 childNodes - returns the child nodes of element
 attributes - returns the attributes nodes of element

innerHTML -  to get or modify the content of  an element

   Suppose  x is a node object (HTML element) , the above properties can be accessed  as  x.innerHTML , x.nodeName, ....

Similarly some DOM methods:

getElementsByTagName(name) - get all elements with a specified tag name
 getElementById(id) - get the element with a specified id
 appendChild(node) - insert a child node to the element
 removeChild(node) - removes a child node from the element

eg. document.getElementById("tableId"), returns the table object.  you can insert , row & columns using the table object.
 to get the content (text)  of an element <p id="test">This is a test</p>  , you can use   innerHTML OR   childNodes and nodeValue properties with the method   getElementById

txt = document.getElementById("test").innerHTML;
 or
  txt=document.getElementById("test").childNodes[0].nodeValue;

Now let us design HTML table  and write javascript code to add or remove rows in a table .   Consider the web page to accept passenger details and child passenger details for booking ticket in a train or bus .

To accept  , passenger details , we need to  insert  rows and cloumns in a table ,  based on the first row  of the table.  The first row is mandatory to accept atleast one passenger details .



Table design with one row and heading



<H1>Passengers Details</H1>


    <TABLE id="PDetailsTable" width="350px" border="1">

     <tr>

       <td>SNO</td>

       <td>Name</td>

       <td>Age</td>

       <td>Gender</td>

       <td>Food Preference</td>

       <td>Berth Preference</td>

       <td>Senior Citizen</td>

       <td>Select to Delete</td>

   </tr>    



        <tr>



            <td> 1 </td>



            <td> <input type="text" name="name" /> </td>

            <td> <input type="text" name="age" /> </td>

            <td>  <select name="Gender">

                     <option value="M">Male</option>

                    <option value="F">Female</option>

                  </select>

           </td>

               

            <td> <select name="Food">

                    <option value="v">Veg</option>

                    <option value="nv">Non-Veg</option>

                </select>

            </td>

              

            <td> <select name="BerthPreference">

                    <option value="l">Lower</option>

                    <option value="m">Middle</option>

                    <option value="u">Upper</option>

                    <option value="sl">Side Lower</option>

                    <option value="su">Side Upper</option>

                </select> </td>

              

            <td><input type="checkbox" name="SCchk" /></td>

          

             <td><input type="checkbox" name="delchk" /></td>



        </tr>    </TABLE> 


Two input  buttons to call   addPassenger function  to insert dynamic row and to call deletePassengerRow  to remove row from the table dynamically.
  


   <input type="button" value="Add More Passengers" onclick="addPassenger('PDetailsTable')" />

    <input type="button" value="Delete Row" onclick="deletePassengerRow('PDetailsTable')" /> 

Two javascript functions  to add and remove dynamic rows and columns  and one more function ( arrangeSno)  to arrange serial numbers when the row is removed from the table are as follows




to arrange serial numbers



 function arrangeSno(tableId)

 {

             var tblObj = document.getElementById(tableId);

             var no_of_rows = tblObj.rows.length;

              for(var i=0; i<no_of_rows-1; i++)

           tblObj.rows[i+1].cells[0].innerHTML = i+1;

 }



To add rows dynamically based on the first row in a table



      function addPassenger(tableId) {


            var tblObj = document.getElementById(tableId);


            var no_of_rows = tblObj.rows.length;
    

// to insert single row

            var row_in_table = tblObj.insertRow(no_of_rows);


// to get the number of colums from the first row


             var colCount = tblObj.rows[0].cells.length;


// to increment sno from the previous row by one

           var rno=eval(tblObj.rows[no_of_rows-1].cells[0].innerHTML) +1;


            for(var i=0; i<colCount; i++) {


// to insert one column

               var column_in_row = row_in_table.insertCell(i);



                column_in_row.innerHTML = tblObj.rows[1].cells[i].innerHTML;

              

                if (i==0)  column_in_row.innerHTML = rno;



// to fill new row with  blank  text box, unchecked checkbox ,  combo selected with index 0 when the row is created , eventhough  the first row of the table having the textbox with filled values , etc...



                switch(column_in_row.childNodes[0].type) {

                    case "text":

                            column_in_row.childNodes[0].value = "";

                            break;

                    case "checkbox":

                            column_in_row.childNodes[0].checked = false;

                            break;

                    case "select-one":

                            column_in_row.childNodes[0].selectedIndex =0;

                            break;

                }

            }

        }





To remove rows dynamically  from the table .



        function deletePassengerRow(tableId) {

                    var tblObj = document.getElementById(tableId);

   
                 var delchkbox=document.bookingForm.delchk;    // where bookingForm is the form name


        var no_of_rows = delchkbox.length;

         for(var i=0; i<no_of_rows;i++)

         {

// heading and atleast one row should be in the table

         if (delchkbox[i].checked && tblObj.rows.length>=3)

         {

             tblObj.deleteRow(i+1);

                 no_of_rows--;

      i--;

          }

                }


          arrangeSno(tableId);        } 


To accept  ,child  passenger details ,  we are creating  elements like textbox , checkbox , dropdown list dynamically. These elements are inserted in the table's columns in a row  as a child element . Table rows and columns are also created dynamically . No row is mandatory . Table heading is displayed , if the table has atleast one row , otherwise , table heading is hidden.

Table design with heading without any initial rows



<H1>Child Passengers Details</H1>

  

    <TABLE id="childPassTable" width="350px" border="1" style="visibility:hidden" >

        <tr>

         <td>SNO</td>

         <td>Name</td>

         <td>Age</td>

         <td>Gender</td>

         <td>Select to delete</td>

    </tr>         </TABLE> 

Two buttons to call  addRowForChild &  deleteRowChild




 <P> <input type ="button" value="Add Child Passengers"  onclick="addRowForChild('childPassTable')">  <input type="button" value="Delete Row" onclick="deleteRowChild('childPassTable')"></P> 

Two javascript functions to add rows / remove rows in a table  and to create textbox , checkbox , combo box dynamically  for accepting child passenger details  .



    function addRowForChild(tableId) {



            var tblObj = document.getElementById(tableId);


            var no_of_rows = tblObj.rows.length;


// to make visible of the header row of the table , if the table has atleast one row
            if(no_of_rows==1)

             tblObj.style.visibility="visible";



// to insert one row of the table

            var row_in_table = tblObj.insertRow(no_of_rows);


//to insert the first column (for SNO)

            var column1 = row_in_table.insertCell(0);



      if (no_of_rows==1) 
         var rno=1;

     else
        var rno=eval(tblObj.rows[no_of_rows-1].cells[0].innerHTML) +1;


            column1.innerHTML = rno;


//to insert the second column (for textbox to accept name)

            var column2 = row_in_table.insertCell(1);

            var element2 = document.createElement("input");

            element2.setAttribute("name", "nameChild");  //to set name of the text box

            element2.type = "text";

            column2.appendChild(element2);


 //to insert the second column (for textbox to accept age)
            var column3 = row_in_table.insertCell(2);

            var element3 = document.createElement("input");

            element3.setAttribute("name", "ageChild");

            element3.type = "text";

            column3.appendChild(element3);


 //to insert the fourth column (for combo box to select gender)

            var column4 = row_in_table.insertCell(3);

            var combo = document.createElement("select");

            combo.setAttribute("name", "genderChild");

            var option = document.createElement("option");

            combo.options[0] = new Option("Male", 1);

             combo.options[1] = new Option("Female", 2);

            column4.appendChild(combo);

// to insert the fifth column (for check box )          

            var column5 = row_in_table.insertCell(4);

           var element5 = document.createElement("input");

            element5.type="checkbox";

            column5.appendChild(element5);

          

        }




       function deleteRowChild(tableId) {


            var tblObj = document.getElementById(tableId);

            var no_of_rows = tblObj.rows.length;


            var i=0;

            while (i<no_of_rows)

            {

                var row_in_table = tblObj.rows[i];

                var chkbox = row_in_table.cells[4].childNodes[0];

                if( chkbox !=null &&  chkbox.checked==true) {

                    tblObj.deleteRow(i);

                    no_of_rows--;

                    i--;

// to hide the table heading , if there is no row

            if(no_of_rows<=1) tblObj.style.visibility="hidden";

                }

                i++;

                }

              

             arrangeSno(tableId);

                   } 





Sample code to send / pass /  process the elements created  dynamically  in the page  to server side.            



  String[] names=request.getParameterValues("name");

  

  String[] birthPreference=request.getParameterValues("BerthPreference");



  String[] nameChild=request.getParameterValues("nameChild");

   .....

   .....

   .....

       for (int i = 0; i < names.length; i++)

    

          System.out.println("Name=" + names[i] + " Birth Preferance= " +  birthPreference[i] );

  

   .......   ........

Pdf Writer in C# without any using Paid dll | Pdf writer using Microsoft.Office.Interop.Word in c#

Below code for PDf Writer by using Microsoft.Office.Interop.Word  dll

Pdf Writer in C# without any using Paid dll | Pdf writer using Microsoft.Office.Interop.Word in c#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using Microsoft.Office.Interop.Word;
using System.Diagnostics;
using Microsoft.Office.Interop;
using System.Reflection;
namespace PdfGenerator
{
    class Program
    {
        static void Main(string[] args)
        {
            CreateDocFileInFolder();
            Microsoft.Office.Interop.Word.Application word =
                new Microsoft.Office.Interop.Word.Application();
          
            object oMissing = System.Reflection.Missing.Value;
            // Get list of Word files in specified directory
            DirectoryInfo dirInfo = new DirectoryInfo(@"C:\New folder\New Folder");
            FileInfo[] wordFiles = dirInfo.GetFiles("*.doc"); word.Visible = false;
            word.ScreenUpdating = false;

            foreach (FileInfo wordFile in wordFiles)
            {     // Cast as Object for word Open method   
                Object filename = (Object)wordFile.FullName;
                // Use the dummy value as a placeholder for optional arguments 
                Document doc = word.Documents.Open(ref filename, ref oMissing,
                    ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                    ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                    ref oMissing, ref oMissing, ref oMissing, ref oMissing);
                doc.Activate();
                object outputFileName = wordFile.FullName.Replace(".doc", ".pdf");
                object fileFormat = WdSaveFormat.wdFormatPDF;
                // Save document into PDF Format  
                doc.SaveAs(ref outputFileName,
                    ref fileFormat, ref oMissing, ref oMissing,
                    ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                    ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                    ref oMissing, ref oMissing, ref oMissing, ref oMissing);
                // Close the Word document, but leave the Word application open.
                // doc has to be cast to type _Document so that it will find the  
                // correct Close method.                  
                object saveChanges = WdSaveOptions.wdDoNotSaveChanges;
                ((_Document)doc).Close(ref saveChanges, ref oMissing, ref oMissing);
                doc = null;

            }
           


        }

        private static void CreateDocFileInFolder()
        {
          
              

                //Start Word and create a new document.
                Microsoft.Office.Interop.Word._Application oWord;
                Microsoft.Office.Interop.Word._Document oDoc =null;
                try
                {
                    object oMissing = System.Reflection.Missing.Value;
                    object oEndOfDoc = "\\endofdoc"; /* \endofdoc is a predefined bookmark */

                    oWord = new Microsoft.Office.Interop.Word.Application();
                    oWord.Visible = true;
                    oDoc = oWord.Documents.Add(ref oMissing, ref oMissing,
                        ref oMissing, ref oMissing);

                    //Insert a paragraph at the beginning of the document.
                    Microsoft.Office.Interop.Word.Paragraph oPara1;
                    oPara1 = oDoc.Content.Paragraphs.Add(ref oMissing);
                    oPara1.Range.Text = "TUIFly Cabin Crew Application";
                    oPara1.Range.Font.Bold = 1;
                    oPara1.Format.SpaceAfter = 24;    //24 pt spacing after paragraph.
                    oPara1.Range.InsertParagraphAfter();
                    // Insert Image

                    string filename1 = @"C:\BBC\tuiflylogo.jpg";
                    // now add the picture in active document reference
                    oDoc.InlineShapes.AddPicture(filename1, Type.Missing, Type.Missing, Type.Missing);



                    //Insert a paragraph at the end of the document.
                    Microsoft.Office.Interop.Word.Paragraph oPara2;
                    object oRng = oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range;
                    oPara2 = oDoc.Content.Paragraphs.Add(ref oRng);
                    oPara2.Range.Text = "TUIfly Netbook Application ";
                    oPara2.Format.SpaceAfter = 6;
                    oPara2.Range.InsertParagraphAfter();

                    //Insert another paragraph.
                    Microsoft.Office.Interop.Word.Paragraph oPara3;
                    oRng = oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range;
                    oPara3 = oDoc.Content.Paragraphs.Add(ref oRng);
                    oPara3.Range.Text = "Dynamic Table for Crew 3LTR Code and Function:";
                    oPara3.Range.Font.Bold = 0;
                    oPara3.Format.SpaceAfter = 24;
                    oPara3.Range.InsertParagraphAfter();

                    //Insert a 3 x 5 table, fill it with data, and make the first row
                    //bold and italic.
                    Microsoft.Office.Interop.Word.Table oTable;
                    Microsoft.Office.Interop.Word.Range wrdRng = oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range;
                    oTable = oDoc.Tables.Add(wrdRng, 3, 5, ref oMissing, ref oMissing);
                    oTable.Range.ParagraphFormat.SpaceAfter = 6;
                    int r, c;
                    string strText;
                    for (r = 1; r <= 3; r++)
                        for (c = 1; c <= 5; c++)
                        {
                            strText = "r" + r + "c" + c;
                            oTable.Cell(r, c).Range.Text = strText;
                        }
                    oTable.Rows[1].Range.Font.Bold = 1;
                    oTable.Rows[1].Range.Font.Italic = 1;

                    //Add some text after the table.
                    Microsoft.Office.Interop.Word.Paragraph oPara4;
                    oRng = oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range;
                    oPara4 = oDoc.Content.Paragraphs.Add(ref oRng);
                    oPara4.Range.InsertParagraphBefore();
                    oPara4.Range.Text = "And Table you Want:";
                    oPara4.Format.SpaceAfter = 24;
                    oPara4.Range.InsertParagraphAfter();

                    //Insert a 5 x 2 table, fill it with data, and change the column widths.
                    wrdRng = oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range;
                    oTable = oDoc.Tables.Add(wrdRng, 5, 2, ref oMissing, ref oMissing);
                    oTable.Range.ParagraphFormat.SpaceAfter = 6;
                    for (r = 1; r <= 5; r++)
                        for (c = 1; c <= 2; c++)
                        {
                            strText = "r" + r + "c" + c;
                            oTable.Cell(r, c).Range.Text = strText;
                        }
                    oTable.Columns[1].Width = oWord.InchesToPoints(2); //Change width of columns 1 & 2
                    oTable.Columns[2].Width = oWord.InchesToPoints(3);

                    //Keep inserting text. When you get to 7 inches from top of the
                    //document, insert a hard page break.
                    object oPos;
                    double dPos = oWord.InchesToPoints(7);
                    oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range.InsertParagraphAfter();
                    do
                    {
                        wrdRng = oDoc.Bookmarks.get_Item(ref oEndOfDoc).Range;
                        wrdRng.ParagraphFormat.SpaceAfter = 6;
                        wrdRng.InsertAfter("A line of text");
                        wrdRng.InsertParagraphAfter();
                        oPos = wrdRng.get_Information
                                       (Microsoft.Office.Interop.Word.WdInformation.wdVerticalPositionRelativeToPage);
                    }
                    while (dPos >= Convert.ToDouble(oPos));
                    object oCollapseEnd = Microsoft.Office.Interop.Word.WdCollapseDirection.wdCollapseEnd;
                    object oPageBreak = Microsoft.Office.Interop.Word.WdBreakType.wdPageBreak;
                    wrdRng.Collapse(ref oCollapseEnd);
                    wrdRng.InsertBreak(ref oPageBreak);
                    wrdRng.Collapse(ref oCollapseEnd);
                    wrdRng.InsertAfter(":::::::");
                    wrdRng.InsertParagraphAfter();
                    object filename = @"C:\New folder\New Folder\MyDoc.doc";
                 
                    oDoc.SaveAs(ref filename, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                        ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing);

                 
                    wrdRng.InsertAfter("THE END.");
                }

                catch (Exception ex)
                {

                    if (oDoc != null)
                    {
                        oDoc.Close();
                    }
                 

                }
                finally
                {
                    if (oDoc != null)
                    {
                        oDoc.Close();
                    }
                }
         


       

        }
    }
}

Volatile versus Synchronised in multithreading in java | Difference between Volatile and Synchronised

This tutorical covers about the differences between  synchronized and volatile  modifier . To know lot more about   volatile keyword and how it works in java? , please visit my earlier tutorial volatile modifier in java . The following are the differences between synchronized and volatile  modifier which is one of the core java interview question..

1. Synchronization ensures  both   visibilty   and  mutual exclusion  whereas volatile  ensures  only visibilty  ( one thread reads the most up-to-date value written by another thread)

2. The volatile modifier is applied  to a field variable  whereas synchronized is applied to methods and block of codes.

3. When using  synchronized modifier, an unlock on monitor  happens before / synchronizes with all subsequent lock  on that monitor.When using volatile ,  a write to a volatile variable  happens before  with all subsequent reads of that variable by any thread

4. Volatile  does not guarantee the atomicity of composite operations such as incrementing a variable where as synchronized modifier  guarantees the atomicity of composite operations.
  for example

   private static volatile int sno = 0;
    public static int getNextSno() {
     return sno++;
       }

The above method won’t work properly without synchronization. Every invocation may not return unique value because increment operator performs  three operations read, add, store.   first it reads the value then increments  plus one  then it stores  back a new value. When a thread reads the field , another thread may enter and read the same value before the first thread writes the incremented value back . Now both thread returns the same sno. Use synchronized on the method getNextSno(),   to ensure that the increment operation is atomic and remove volatile modifier from sno.

4. A thread acquires or releases a lock on a  monitor to enter or exit  a synchronized method or  block of code  where as a thread does not need to aquire / release a monitor to  read or write a volatile variable.  i.e.  but both have the same memory effects.

5.   final variable can not be a volatile where as final method can be synchronized

6.  volatile variable  can be null where as synchronization can not be done on null object .

7. In some situations , code is simplified  using volatile  than  using synchronized. At the same time,  we have to be careful when using volatile , code using volatile is weaker (easily broken)  than synchronized  as shown in the above example (4th point).