How to measure the a time-span in seconds using System.currentTimeMillis()?

Question

How to convert System.currentTimeMillis(); to seconds?

long start6=System.currentTimeMillis();
System.out.println(counter.countPrimes(100000000)         


        

Answer 1

I have written the following code in my last assignment, it may help you:

// A method that converts the nano-seconds to Seconds-Minutes-Hours form
private static String formatTime(long nanoSeconds)
{
    int hours, minutes, remainder, totalSecondsNoFraction;
    double totalSeconds, seconds;


    // Calculating hours, minutes and seconds
    totalSeconds = (double) nanoSeconds / 1000000000.0;
    String s = Double.toString(totalSeconds);
    String [] arr = s.split("\\.");
    totalSecondsNoFraction = Integer.parseInt(arr[0]);
    hours = totalSecondsNoFraction / 3600;
    remainder = totalSecondsNoFraction % 3600;
    minutes = remainder / 60;
    seconds = remainder % 60;
    if(arr[1].contains("E")) seconds = Double.parseDouble("." + arr[1]);
    else seconds += Double.parseDouble("." + arr[1]);


    // Formatting the string that conatins hours, minutes and seconds
    StringBuilder result = new StringBuilder(".");
    String sep = "", nextSep = " and ";
    if(seconds > 0)
    {
        result.insert(0, " seconds").insert(0, seconds);
        sep = nextSep;
        nextSep = ", ";
    }
    if(minutes > 0)
    {
        if(minutes > 1) result.insert(0, sep).insert(0, " minutes").insert(0, minutes);
        else result.insert(0, sep).insert(0, " minute").insert(0, minutes);
        sep = nextSep;
        nextSep = ", ";
    }
    if(hours > 0)
    {
        if(hours > 1) result.insert(0, sep).insert(0, " hours").insert(0, hours);
        else result.insert(0, sep).insert(0, " hour").insert(0, hours);
    }
    return result.toString();
}

Just convert nano-seconds to milli-seconds.