To prevent memory cheating you can do one of the following:
Store the most important values in arrays of digits rather than in
variables
Store the value as string as well and whenever you modify
it check to see if it matches the string.
Take a look at MochiDigits classes from Mochi (Actionscript 3) and come up with a Java port.
https://code.google.com/p/cunitescore/source/browse/trunk/as3/unitescore/mochi/MochiDigits.as?r=92