Write a program that replaces each line of a file with its reverse. For example, if you run

java Reverse HelloPrinter.java
then the contents of HelloPrinter.java are changed to
retnirPolleH ssalc cilbup
{
)sgra ][gnirtS(niam diov citats cilbup

{
wodniw elosnoc eht ni gniteerg a yalpsiD //
;)"!dlroW ,olleH"(nltnirp.tuo.metsyS
}
}

Of course, if you run Reverse twice on the same file, you get back the original file.