Problem in ConnectionPool

[appu sharma]

  package util;

/**
 *
 * @author vinit
 */
import java.io.*;
import java.sql.*;
import java.util.*;

public class ConnectionPool
{
      static final int MAX_CONNECTIONS = 20;//Maximum nuber of Connection
      static Vector connections = null;

      static ConnectionPool instance = null;
//removeAllConnection removes all the connections
      public synchronized void removeAllConnections()
      {
          try{
              if(connections == null)
                    return;
              int sz = connections.size();
              for(int i=0; i<sz; i++)
              {
                   Connection c = (Connection)connections.elementAt(i);
                   c.close();
              }
              connections.removeAllElements();
              connections = null;
         }catch(SQLException sqlE){System.out.println(sqlE);}
      }

      public static synchronized ConnectionPool getInstance()
      {
           if(instance == null)
                 instance = new ConnectionPool();
           return instance;
      }

      public  synchronized void initial()
      {
           if(connections == null)
           {
               try
               {
	       String userName = "root";
               String password = "123456";
               String url = "jdbc:mysql://localhost/students";
               Class.forName ("com.mysql.jdbc.Driver").newInstance ();

               connections = new Vector();
               int count = 0;
                while(count < MAX_CONNECTIONS)
                {

		Connection c = DriverManager.getConnection (url, userName, password);
                connections.addElement(c);
                count++;
                 }

		}catch (Exception e)
        	   {
               		System.err.println ("Cannot connect to database server");
           	   }

		System.out.println("over");
             }
      }

      public synchronized Connection getConnection()
      {
          Connection c = null;
          if(connections == null)
              return null;
          if(connections.size() > 0)
          {
                c = (Connection)connections.elementAt(0);
                connections.removeElementAt(0);
          }
          return c;
      }

      public synchronized void putConnection(Connection c)
      {
           connections.addElement(c);
           notifyAll();
      }
}
  

After that when i use it in servlet i get an error.

   ConnectionPool cp= ConnectionPool.getInstance();
           cp.initialize();   //error   in Netbeans it is saying like that (pakage cp doesnt exist <identifier> expected
           Connection con=cp.getConnection(); 

and the error is
C:\Documents and Settings\vinit\My Documents\NetBeansProjects\WebApplication2\nbproject\build-impl.xml:568: The module has not been deployed.
please help me
Thank you
vinit

[Ravishanker kumar]

I think this is not problem of ConnectionPool. It is something deployment issue. Please check why model is not geting deployed.

~Ravi

[Jan Cumps]

error in Netbeans it is saying like that (pakage cp doesnt exist <identifier> expected

I feel that this is not the exact error message you get. Can you please copy the complete error, and show that to us?

[appu sharma]

Thank i correct the error its problem of try and catch.
its silly mistake and i am sorry for that.
thanks for your time

[Lorand Komaromi]

Don't reinvent the wheel, use Apache DBCP, Oracle UCP, etc.!