Well i am pretty confused between the three,,,,i tried going through the java forums http://forum.java.sun.com/thread.jspa?threadID=583383&messageID=2981007 and
http://forum.java.sun.com/thread.jspa?threadID=671804&messageID=3926799

but just couldnt make out anything.......Could someone please explain it in a bit simpler terms.....Thanks a tonne :)

No idea. I've never used the revalidate() for the whole content, but rather only for certain components. The only time I found it useful was when using a JTable and I needed to update the content inside of it. This also changed the size of the table.