Question

try{
      String query= "select user_name from user";
      ResultSet rs = queries.performQuery(query);

while(rs.next()){
        System.out.println("User Name :" + rs.getString("user_name"));
      }

in another class I have something like this:

public ResultSet performQuery(String query) throws SQLException
    {       
        try 
        {
              connection = DriverManager.getConnection(sqlUrl,sqlUser,sqlPassword);
              stmt = connection.createStatement();
                  rs = stmt.executeQuery(query);
        } 

        catch(SQLException ex) 
        {
        }

        finally{
            close(rs);
            close(stmt);
            close(connection);
        }
        return rs;
    }

Now I get the error Operation not allowed after ResultSet closed, and it’s obviously because I’m closing the rs/stmt/connection.

I don’t have my code with me so this is just off the top of my head, disregard any syntax errors and I hope my question is still clear enough.

So my question is this:

If you want to have a method that for example performs queries, and you call that in another method and then do rs.next, what is the appropriate way to close the resultset/stmt/connection? To me it makes sense to close them the performQuery, but that gives me the error.

Answer 1

if you are using ResultSet then it will need the Connection to load more rows . for example if your query returns 1000 record , first the ResultSet will hold 41 row in memory then when you iterate over this number it will use the Connection to load another chuck of records .in your case i would use RowSet for more explanation read this