haha this is from java for dummies right? even i've been trying to figure out the same problem, but its probably coz the author has worked on an older version of java, and that makeshift method of his is no longer valid...gonna try out the suggestion put here and lets see if it works...
the problem has something to do with the 0 in charAt, coz that doesnt seem to accept null values any more...

UPDATE : ok i tested the suggestion...