Many connections from an Oracle8i pooled connection returns statement closed.

package package6;
import oracle.jdbc.pool.*;
import java.sql.*;
import javax.sql.*;

/**
 * package6.workerClass1
 * 
 * @author Me
 */
public class workerClass1 extends Thread {
  // protected  OracleConnectionPoolDataSource ocpds = null;
  // protected  PooledConnection pc = null;

  protected Connection conn = null;

  protected  int threadNumber = 0;
  /**
   * Constructor
   */

  public workerClass1() {
  }

  public void doWork( ) throws SQLException {

    // Create a pooled connection
    // pc  = ocpds.getPooledConnection();

    // Get a Logical connection
    // conn = pc.getConnection();

    // Create a Statement
    Statement stmt = conn.createStatement ();

    // Select the ENAME column from the EMP table
    ResultSet rset = stmt.executeQuery ("select ename from EMP");

    // Iterate through the result and print the employee names
    while (rset.next ())
      //  System.out.println (rset.getString (1));
      ;

    // Close the RseultSet
    rset.close();
    rset = null;

    // Close the Statement
    stmt.close();
    stmt = null;

    // Close the logical connection
    conn.close();
    conn = null;

    // Close the pooled connection
    // pc.close();
    // pc = null;

    System.out.println( "workerClass1.thread# "+threadNumber+" completed..");

  }

  public void setThreadNumber( int assignment ){
    threadNumber = assignment;
  }

  // public void setConnectionPoolDataSource(OracleConnectionPoolDataSource x){
  //   ocpds = x;
  // }

  public void setConnection( Connection assignment ){
    conn = assignment;
  }

  public void run() {
    try{
      doWork();
    }
    catch ( Exception ex ){
      ex.printStackTrace();
    }
  }

}