Replace all instances of System.currentTimeMillis() with System.nanoTime()

[cohen990]

according to - http://stackoverflow.com/questions/1770010/how-do-i-measure-time-elapsed-in-java, System.currentTimeMillis() is your computer's set clock whereas System.nanoTime() uses the clock on your processor and cannot be changed by the user. Plus it works in nanoseconds :) (although the invocation can purportedly take more than a millisecond to process.