Thread: DAO exception

Hi all iam running this code for datasource from server .iam getting this error .Please do let me know.

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import org.apache.log4j.Logger;
 
public class AbstractDAO
{
    /** The datasource used by this object. */
    protected DataSource dataSource = null;
	protected String jndiDataSourceName = null;
	public static String DEFAULT_SCHEMA;
	private static Logger logger = Logger.getLogger(AbstractDAO.class);
	/**
	 * Constructor for the class.
	 * @param jndiDataSourceName the JNDI name of the datasource
	 * @throws AbstractDAO if the datasource cannot be located
	 */
	protected AbstractDAO(String jndiDataSourceName) throws DAOException
	{
		this.jndiDataSourceName = jndiDataSourceName;
		try
		{
			dataSource = getDataSource(this.jndiDataSourceName);
		}
		catch(NamingException ne)
		{
			logger.error("AbstractDAO:: AbstractDAO() -Unable to create the Data Access Object " + ne);
			throw new DAOException("AbstractDAO:: AbstractDAO() - Unable to create the Data Access Object",ne);
		}
	 }
	/**
	 * Looks up and returns a DataSource object from the Naming service.
	 *
	 * @param jndiName the name used to bind the DataSource object
	 *  in the Naming service
	 * @return the DataSource object specified by the jndiName parameter
	 * @throws NamingException if the DataSource object cannot be located
	 *  within the Naming service
	 */
	public DataSource getDataSource(String jndiName) throws NamingException
	{
		InitialContext context = new InitialContext();
		this.dataSource = (DataSource) context.lookup(jndiName);
		return dataSource;
	}
	/**
	 * Returns a Connection object from a specific DataSource.
	 * @param jndiDataSourceName the name of the DataSource
	 * @return Connection the request Connection object
	 * @throws Exception is an error is encountered
	 */
	protected Connection getConnection() throws SQLException
	{
		Connection connection = dataSource.getConnection();
		if(DEFAULT_SCHEMA != null)		{
			connection.createStatement().execute("ALTER SESSION SET CURRENT_SCHEMA="+DEFAULT_SCHEMA);
			}
		return connection;
	}
    /**
     *  This method is used to check the string value is null or not
    */
	protected boolean isBlank(String value)
	{
	    if(value == null || value.equals(""))
	    {
	    	return true;
	    }
	    else
	    {
	    	return false;
	    }
	}
	/**
	 * Method      : close
	 * Description : This Method closes object for a specific DataSource.
	 * @param resultSet
	 * @param statement
	 * @param connection
	 */
	protected void close(ResultSet resultSet, Statement statement, Connection connection) throws DAOException
	{
		try{
			if(resultSet!= null)
			{
	    		try
	    		{
	    			resultSet.close();
	    		}
	    		catch(Exception ex)
	    		{
	    			logger.error("AbstractDAO:: close() -  Unable to close result set object");
	    			throw new DAOException("AbstractDAO:: close() - Unable to close result set object");
	    		}
			}
			if(statement != null)
			{
				try
				{
					statement.close();
				}
				catch(Exception ex)
				{
					logger.error("AbstractDAO:: close() -  Error While closing the statement "+ex);
					throw new DAOException("AbstractDAO:: close() - Unable to close statement object");
				}
			}
			if(connection != null)
			{
				try
				{
					connection.close();
				}
				catch(Exception ex)
				{
					logger.error("AbstractDAO:: close() -  Error While closing the connection "+ex);
					throw new DAOException("AbstractDAO:: close() - Unable to close connection object");
				}
			}
		}
		catch(Exception exception)
		{
			logger.error("AbstractDAO:: close() -  Error While closing the connection "+exception);
			throw new DAOException("AbstractDAO:: close() -  Error While closing the connection");
		}
	}
	/**
	 * Method       : roll back
	 * Description  : This method roll back the transaciton.
	 * @param connection
	 */
    protected void rollback(Connection connection) throws DAOException
    {
	if (connection != null)
	    try {
	    	connection.rollback(); 
	    }catch(Exception ex)
	    {
	    	logger.error("AbstractDAO:: rollback() -  Error While roll back the transaciton "+ex);
			throw new DAOException("AbstractDAO:: rollback() - Unable to roll back the transaciton");	
	    }
    }
      /**
     * Method       : executeUpdate
     * Description  : this method used to update the DB.
     * @param connection
     * @param sql
     * @throws DAOException
     */
    protected void executeUpdate(Connection connection, String sql) throws DAOException
    {
    	logger.info("AdminGuiAbstractDAO:: executeUpdate() - In executeUpdate method");
    	PreparedStatement statment = null;
 		try
 		{     			
 			statment = connection.prepareStatement(sql);						
 		    statment.executeUpdate(); 			
 		}
 		catch(SQLException sqle)
 		{
		    logger.debug("AbstractDAO:: executeUpdate() - Unable to Update " + sqle);
		    throw new DAOException(sqle);
		}
 		catch(Exception exception)
 		{			
		    logger.debug("AbstractDAO:: executeUpdate() - Error in executeUpdate."+exception);
		    throw new DAOException("AbstractDAO:: executeUpdate() - "+exception);
		}
 		finally
 		{
		    close(null, statment, null);
		}
    }
}

iam getting the below error for this application
12-10@16:35:36 ERROR(AbstractDAO.java (AbstractDAO.<init>()):34) - AbstractDAO::AbstractDAO() -Unable to create the Data Access Object javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file: java.naming.factory.initial

thanks