/***************************************************************************** * Example program to declare and initialize two StopWatch objects. * Then swap them by merely swapping the reference names. * * Compilation: javac PlayTime.java * Execution: java PlayTime * Dependencies: StopWatch.java, StdOut.java * ****************************************************************************/ public class PlayTime { public static void main(String[] args) { Stopwatch watchOne = new Stopwatch(); // waste time so it is large enough to be measurable for (int i = 0; i < 1e8; i++); Stopwatch watchTwo = new Stopwatch(); // waste time so it is large enough to be measurable for (int i = 0; i < 1e8; i++); // right now, watchOne is older StdOut.println("watchOne " + watchOne.elapsedTime()); StdOut.println("watchTwo " + watchTwo.elapsedTime()); Stopwatch watchTmp = watchOne; watchOne = watchTwo; watchTwo = watchTmp; // swapped! now watchTwo is the older one // e.g. watchTwo.elapsedTime() returns a value // (slightly) larger than watchOne.elapsedTime() StdOut.println("watchOne " + watchOne.elapsedTime()); StdOut.println("watchTwo " + watchTwo.elapsedTime()); } }