Stop Watch Program - To measure the amount of time to process each input

public class Stopwatch { 

    private final long start;

    public Stopwatch() {
        start = System.currentTimeMillis();
    } 

    // return time (in seconds) since this object was created
    public double elapsedTime() {
        long now = System.currentTimeMillis();
        return (now - start) / 1000.0;
    } 

}