throwing an Exception after first exceution ..

[shiva mistry]

When I try to Enter sid second time from command prompt it throws an Exception like Connection is closed but if i comment out the con.close() then it allows to perform another query ,I do not know what to do ?can any one help please?

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ContoDB {

	private Connection con = null;

	private PreparedStatement preSql = null;

	public ContoDB() {
	}

	public ContoDB(String url, String username, String password) {
		super();

		try {
			DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
			con = DriverManager.getConnection(url, username, password);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public boolean getStudentBysid(int sid) {
		Statement sql = null;
		ResultSet result = null;
		PreparedStatement preSql = null;
		try {
			preSql = con
					.prepareStatement("SELECT * FROM STUDENT WHERE SID = ? ");
			preSql.setDouble(1, sid);
			result = preSql.executeQuery();
			// sql = con.createStatement();
			// result =
			// sql.executeQuery("SELECT * FROM STUDENT WHERE GPA >= 3.9 ");
			while (result.next()) {

				System.out.println("			Student ID :" + result.getInt("SID"));
				System.out.println("			Studnet Name:" + result.getString("SNAME"));
				System.out.println("			Student GPA:" + result.getDouble("GPA"));
				System.out.println("			Student HsSize:" + result.getInt("SIZEHS"));
			}

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // finally {
			// try {
			// result.close();
			// preSql.close();
			// sql.close();
			// con.close();
		// } catch (SQLException e) {
		// TODO Auto-generated catch block
		// e.printStackTrace();
		// }

		// }
		return true;
	}

	public boolean getApplication(int sid) {
		boolean aplication = false;
		PreparedStatement preSql = null;
		ResultSet result = null;

		try {
			preSql = con
					.prepareStatement("SELECT * FROM APPLICATION WHERE SID = ?");
			preSql.setInt(1, sid);
			result = preSql.executeQuery();
			while (result.next()) {
				System.out.println("                     Studnet ID: " + result.getInt("SID"));
				
				System.out.println("                     College Name: " + result.getString("CNAME"));
				System.out.println("                     Major: " + result.getString("MAJOR"));
				System.out.println("                     Decision: " + result.getString("DECISION"));
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}// finally {
			// try {
			// con.close();
			// result.close();
			// preSql.close();
		// } catch (SQLException e) {
		// e.printStackTrace();
		// }
		// }
		return aplication = true;

	}
}

import java.io.Console;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ConnectionTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		ContoDB c = new ContoDB("jdbc:oracle:thin:@localhost:1521:xe",
				"hr", "orcl");
		int i = 0;
		Console console = System.console();
		System.out.println("Choose Option :");

		String option = "";
		do {
			System.out.println(" Press 1 for Student Info");
			System.out.println(" Press 2 Student Application:");
			System.out.println("Press 3 for Exit:");
			int sel = Integer.parseInt(console
					.readLine("Enter your Selection\n:"));
			switch (sel) {
			case 1:
				int sid = Integer.parseInt(console
						.readLine("\nEnter Student ID:"));
				System.out
						.println("*******************************The info of Student**************************************");
				c.getStudentBysid(sid);
				break;
			case 2:

				int sid1 = Integer.parseInt(console
						.readLine("\nEnter Student ID:"));
				System.out
						.println("*******************************The Application info of Student**************************************");
				c.getApplication(sid1);
				break;
			case 3:
				System.out.println("Bye");
				System.exit(0);
				i++;
				break;
			default:
				System.out.println("Please Enter Valid Selection:");
				break;

			}
			option = console
					.readLine("\nPress Yes to continue or Any Other Key to Exit.");
		} while (i == 0 && option.equalsIgnoreCase("yes"));
	}
}

[Paul Clapham]

Don't close the connection, then.