Convert string to time and calculate difference

Question

I have two strings: 1.20.2 and 1.23.0

They are minutes, ie 1.20.2 stands for 1 minute 20.2 seconds.

How can I convert these strings into time values and then do a subtraction?

For example:

1.23.0 - 1.20.2 = 0.2.8

Answer 1

I would prefer to use Joda Time , its a very good API for date/time operations. Otherwise you have to reinvent the wheel...

In my opinion the name of the classes and functions of the API are very intuitional

This is the code ( successfully tested! ):

PeriodFormatter pf = new PeriodFormatterBuilder()
.printZeroAlways() // print zero minutes
.appendMinutes()
.appendSeparator(".")
.appendSecondsWithMillis()
.toFormatter();

Period p1 = pf.parsePeriod("1.20.2");
Period p2 = pf.parsePeriod("1.23.0");

Period diff = p2.minus(p1);
System.out.println(diff.toString(pf));

// output:
// 0.2.800

Answer 2

You should use the SimpleDateFormat , like this:

    String min1 = "1.20.2";
    String min2 = "1.23.0";

    SimpleDateFormat sdf = new SimpleDateFormat("m.ss.S");

    Date parse = sdf.parse(min1);
    Date parse2 = sdf.parse(min2);

    long diff = parse2.getTime() - parse.getTime();
    Date date = new Date(diff);
    String format = sdf.format(date);
    System.out.println(format);

This will print 0.02.998 . To get your expected result of 0.2.8 you have to pass 1.20.200 as min2 as this is how the SimpleDateFormat interprets this value.

Answer 3

Use SimpleDateFormat to convert them to Date objects. Then use Date.getTime() to get the "milliseconds since epoch", compute the difference.

Answer 4

Is the time always in the same format? If so, you can use the split(String regex) method, for example:

String time1 = "1.20.2";
String[] splitTime1 = time1.split(",");

This will give you a string array. I don't know how important it is that you convert them into a DateTime - personally I would convert each item in the array to an int of the same units, for example:

int secondsTime1;
secondsTime1 = (splitTime1[0] * 60) + (splitTime1[1]) + (splitTime1[2] * Math.pow(10, -3));

//Assume you do the same with the second time to get secondsTime2;

int difference = secondsTime1 - secondsTime2;

Answer 5

This should be easy, have you attempted to solve this yourself?

Anyway, pseudo code will look like

For each string
    pos = string.indexOf(".")
    Split string into two parts min, sec based on the index "pos"
    stringSecs = min*60 + sec

Find difference of stringSecs by regular subtraction.

Convert back to required format using min = answer/60, sec=answer%60