Scrollbars/Viewports etc.

Question

Hello,
I am new to Swing, well, sort of, but I have a problem that I'm not really looking for the answer to, more just in case there's some sort of weird bug that I'm not aware of. I don't want to be banging my head against a brick wall!
I'm trying to write a kind of IRC client. The server was simple, but I need to write a Java GUI - lots of clients, all on different platforms (lots on OS X interestingly). All I want to do is to do a text box that's like the one I'm typing into at the moment, where it automatically scrolls down the the lowest possible position as you type.
However, what I've found, is that after having tried three approaches to this:
1: do the math(s) and call the setRectToVisible(...) method
2: use someone else'e code from the internet that does similar maths
3: do scrollPane.getVerticalScrollBar().setValue(scrollPane.getVerticalScrollBar().getMaximum());
That no matter what I do, it doesn't work... And it doesn't work in pretty much the same way, which is why I'm asking the question. It sort of works. Most of the time, it's one text line above the bottom. Sometimes it goes right up to the top, and rarely, it does what it's supposed to do.
Is this a known problem? Am I doing something extremely stupid? I haven't bothered posting all the code as people get a bit bored of that, but I'm pretty sure that's OK. It's a scrollpane with the child set to a JTextPane object. Nothing else.
Many thanks,
K.

Answer 1

I haven't bothered posting all the code as people get a bit bored of that,Well all the code is not part of the problem. You should be posting the part of the code that is directly related to the problem. This is called a SSCCE.
Actually I get bored more reading a question where 90% of the text is not related to the problem. Keep the question simple and accurate.
All I want to do is to do a text box that's like the one I'm typing into at
the moment, where it automatically scrolls down the the lowest possible position as you type.I don't understand the question. This is the default behaviour of a JTextPane added to a JScrollPane. As you type the text pane scrolls. I'm assuming of course that you added the scroll pane to the frame.
I suspect your real question is about appending text to a text pane as it is received from the Server.
Or are you suggesting that you can actually type text into the text pane at the same time as the Server is appending text to the text pane?
Assuming you are just trying to append text the see the answer above, but use textComponent.getDocument().getLength() instead of the getText() method (its more efficient).
If you need further help then you need to create a [url http://homepage1.nifty.com/algafield/sscce.html]Short, Self Contained, Compilable and Executable, Example Program (SSCCE) that demonstrates the incorrect behaviour, because I can't guess exactly what you are doing based on the information provided.
And don't forget to use the [url http://forum.java.sun.com/help.jspa?sec=formatting]Code Formatting Tags so the code retains its original formatting.