This is a quick easy solution to creating a j2me scrollbar. It has not yet been tested, but i think it will work. The idea came when i was working with percentages.
SOLUTION
PLEASE NOTE THAT YOU MUST KNOWN THE MAXIMUM LINES. THIS CAN BE GOTTEN BY SOME MANIPULATION WITH THE FONT, STRING AND WITH A WHILE LOOP. ALL YOU HAVE TO DO IS, USE THE FONT CLASS TO DETERMINE THE TEXT THAT CAN ENTER ONE LINE. STORE THAT LINE IN A VECTOR THEN CONTINUE, TILL YOU ARE DONE WITH THE TEXT. I remember i have coded this before but this is not the point of this thread, any real j2me developer should know how to do that i guess. WHEN YOU KNOW THE MAXIMUM NUMBER OF LINES, THEN YOU MUST ALSO KNOW THE PRESENT LINE THE USER IS AT. THIS IS SIMPLE, IF YOU ARE USING A VECTOR TO STORE EACH LINE THEN USING A WHILE LOOP TO DISPLAY, THEN THE FIRST ELEMENT THAT IS PRINTED OUT IS THE CURRENT LINE, GET THE NUMBER. Then you use this:
scrollbar = (currentLine/maxLine) * (deviceWidth - scrollBarLength)
this will give you the position where your scrollbar should start(be). Lets take an example. The maximum line is 1000 and the current line is 500. The device Width is 320 and the scrollbar length is 10.
scrollbar = (500/1000) * (320 - 10)
The result is equal to 155, which is half of the screen and the user is at half of the page. So am damn sure it will work. Please note that the value you get is the starting position of the scrollbar on the y axis. The value should be convert to an int since this can give funny result. If you have any question or comment drop it here.