public void start(){
  if (mState == State.RUNNING) {
    throw new IllegalStateException();
  }
  mStart=System.nanoTime();
  mState=State.RUNNING;
  mStartCount++;
}

public void start ( ) { if ( mState == State . RUNNING ) { throw new IllegalStateException ( ) ; } mStart = System . nanoTime ( ) ; mState = State . RUNNING ; mStartCount ++ ; }
start the clock ticking on a new time interval .
