long start = System.currentTimeMillis();
long end = System.currentTimeMillis();
end -= start;
long one= (end / 1000) % 60;
long two= (end / (1000 * 60)) % 60;
long three= (end / (1000 * 60 * 60)) % 24;
System.out.println(String.format("Done in %02d:%02d:%02d:%d", three, two, one, end));
Что...