Connection pooling is a collection of database connections that is maintained by memeory.that can be reused.once an application has finished its physical connnection the connection is recycled rathe than being destroyed.

with regards

Francis.a

Actually i want to know about how can we write connection pooling using Vector ArrayList classes in java.

will u please explain with sample code.

Regards

Suresh

hi suresh this my code for connection pool

public class ConnectionPool {

Vector connections null;
static ConnectionPool instance null;
public static final int MAX_CONNECTIONS 10;

public synchronized void removeAllConnections() {

if (connections null) {
return;
}

try {
int sz connections.size();
for (int i 0; i < sz/2; i++) {
Connection c (Connection) connections.elementAt(i);

c null;
connections.remove(i);
}

if (connections! null && connections.size() > 0) {
connections.removeAllElements();
}
connections null;
} catch (Exception e) {
System.out.println( Error + e);
}
instance null;

}

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

return instance;
}

public synchronized void initialize() {

if (connections null) {

try {
Class.forName( com.mysql.jdbc.Driver );
connections new Vector();
int count 0;
while (count < MAX_CONNECTIONS) {
Connection c DriverManager.getConnection( jdbc:mysql://localhost/lara );
connections.addElement(c);
count++;
}
System.out.println( total connections created r: + count);
} catch (Exception e) {
System.out.println( initialise:Exception );
e.printStackTrace();
instance.removeAllConnections();

}
}
}

public synchronized Connection getConnection() {
System.out.println( 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) {

if (c ! null) {
connections.addElement(c);
notifyAll();
}
}
}

Ther's some problem in above code .
1.The constructor is missing
2.Initialize method has not been called from in any where in the code.

The pool which i will suggest is as below.
1.define two variables MIN_CONNECTION(miimum no of connection tat sud be in the pool) and MAX_CONNECTION (max no pf coonections)

2. In the initialize method intialize the pool to have minimum no of connections as specified in the MIN_CONNECTION variable.

3.From the constuctor call the initialize() method to have minimum no of connections in the connection poll when the instance gets created

4.There should be a getConnection(long timeout) method .Instead of directly returning null when a connection is not available we should wait sometime as specified by timeout parameter to get a free connection .If still its not available return null.

Let me know if u have any question...