i have learnt how to solve the array out of bound error!!!!
i solved a problem on my own, reflecting on this post. Ya!.
i download any java editor, i google and http://www.jedit.org/index.php?page=download came up.
i browsed to the error file
LookangVernierCaliper04FKH.java for example
look for the error line it was, say line 803
with jedit is easy to locate that line,
for example the old code is //xp=xm2t[vs]; // this is the way to determine position of lower scale pointer
that means vs jumps to a illegal value from what was defined in the variable page
for my example xm2t is defined as an array n2t where n2t is defined as 11.
insert and modify logically . my example is
// adding this code to solve array out of bound error 803
// http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1183.0 solution discussed
if(vs > -1 && vs< n2t)vsidarray=vs;
else vsidarray=0;// or other valid values.
// this line is causing array out of bound error 803
//xp=xm2t[vs]; // comment that line that is causing the array out of bound error
xp=xm2t[vsidarray]; // modify logically to this
this way, no more array error out of bound 12 because n2t is 0 to 10.