Question

So I’m having issues with my program. Basically this far the program is like a MySQL based chat. It stores messages in database and reads them. I’m having problems with the reading. What it does right now is ever 5 seconds re-read all the messages in the database. I tried to make it read only the new messages but that’s not working out too well. This is my code:

public static void readChat()
{
    try
    {
        MySQL.sqlConnect();
        try
        {
            Statement st = con.createStatement();
            ResultSet res = st.executeQuery("SELECT * FROM  table1");
            while (res.next())
            {
                if (lastLine < res.getInt("id"))
                {
                    String message = res.getString("message");
                    Gui.out.append(message + "\n");
                    lastLine = res.getInt("id");
                }
            }
        }
        catch (SQLException s)
        {   
            System.out.println("SQL code does not execute.");
        }
        MySQL.sqlDisconnect();
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
}

I’m not sure how to make this efficient. It takes way too long to execute that. If the id is 23 I can’t even see the messages appear because it takes longer than 5 seconds. I added the

if (lastLine < res.getInt("id"))

and

lastLine = res.getInt("id");

in my effort to make it read only the new messages but it did not work as expected. I think it still executed line by line, just doesn’t show it in the chat. There’s got to be an easier way.

EDIT: Alright, so I fixed the problem with not seeing messages, (I forgot to remove the part of the code that cleared the chat every 5 seconds). But it still takes a long time to send messages, about 3-4 seconds?

Answer 1

Try this, and you will wonder 🙂

ResultSet res = st.executeQuery("SELECT * FROM  table1 where id > "+lastLine);

instad

ResultSet res = st.executeQuery("SELECT * FROM  table1");

and get result without if

       while (res.next())
        {
                String message = res.getString("message");
                Gui.out.append(message + "\n");
                lastLine = res.getInt("id");
        }

Of course make sure index on id field