Why should we close a connection

Question

Hi,
Connection conn = DriverManager.getConnection (databaseUrl, userName, userPassword);
Why should we close a connection
conn.close();
Even when i give no "close command", it works !
Thank You
Edited by: ashipj on ?? ????????, ???? ?:?? ???????

Answer 1

My code frequently fetches data from database, so i created a class like this
public class ConnectToDatabase
/*             public ConnectToDatabase()
                                Connection conn;
     public ResultSet selectS(String userQuery) throws Exception
          String userName = "root";
          String userPassword = "gal";
          String databaseUrl = "jdbc:mysql://localhost:3306/test";
          Class.forName ("com.mysql.jdbc.Driver");
          Connection conn = DriverManager.getConnection (databaseUrl, userName, userPassword);
          String query = userQuery;
          Statement S=conn.createStatement();
          ResultSet RS=S.executeQuery(query);
                                //conn.close;
          return RS;
                                //conn.close;
/*              public void closeConnection()
                                conn.close;
}and from the main code i make call as given below (it works fine)
ConnectToDatabase CTD=new ConnectToDatabase();
ResultSet result=CTD.selectS(String userQuery);
//CTD.closeConnection();Now my problem is
1) If try to give "conn.close()" before "return RS;" It will show error (RS cannot be fetched after closing connectio)
2) If write conn.close after return it wont be executed (ofcourse - unreachable statement)
3) If use "CTD.closeConnection();" it gives errror saying that "cannot find conn(in closeConnection()) " i dont know why constructor is noy loaded.