JTextArea displaying large files

Question

Simple, much talked about question.
I searched for an answer, but was not satisfied.
I am trying to display larger files in a JTextArea, say 20-30MB each.
What is the fastest way to read, and then to write in into the JTextArea.
Currently I am using a BufferedReader, and readline, and append about 3000 lines to a StringBuffer, and then append every 300 lines to the text area unitl EOF.
It takes the files about 60-70 secs to load on a 1ghz 512MB Win machine.
Which is a long times, especially because requirements have us on some 8 year Sun boxes.
Questions are........fastest way to read and display.
I thought about overiding the text area's document for random access, but would hope for a simplier answer since this requirement is not high on the users list.
Am hoping that someone can just post an example since they solved this problem a long time ago.

Answer 1

I have done it!
The only problem with using a Reader is that you load everything into memory...so if you have a file larger than your -Xmx you are screwed.
I used a combination of a JTextArea, JScrollBar and a RandomAccessFile. First I disabled the verticle scrollbar in the JTextArea. I then placed my JScrollBar next to it so it looks like it's the JTextArea's. My JScrollBars min and max values are 0 and RandomAccessFile.length()... Thus making the scrollbar byte based. I then set the scroll increment to the average number of bytes per line. And finally add a listener to the scrollbar that listens for changes... Essentially I only read a small portion of the file, and when you scroll, it reads the next part, rounding to the nearest endline. When you scroll backwards, it reads backwards...unlike a Reader. There are many things that need to be accounted for since it is not line-based but byte-based, or if the filesize changes. For my needs, it does exactly what I need it to, reads large files quickly. Oh I also disabled word wrap. I'm sure you could think of some way to incorperate this idea to your needs.