Question

I’m a beginner in java/android but I am trying to make an app. A user must type in a time like 13:45 and then the app should substrat ex. 00:30 minutes from that time. That gives the result 13:15.
I have tried many different things but it wont work.

I have somthing like this. (At this stage I’ve hardcoded two times)

    String time1 = "00:30";
    String time2 = "13:45";

SimpleDateFormat format = new SimpleDateFormat("HH:mm");
Date date1 = format.parse(time1);
Date date2 = format.parse(time2);
long result= date2.getTime() - date1.getTime(); 

String strLong = Long.toString(result);

textView4.setText(strLong);

I’m getting an error in the format.parse(time1) and format.parse(time2). Is this the right way to do this? Any help? Thanks

Answer 1

Use Calendar type.

SimpleDateFormat format = new SimpleDateFormat("HH:mm");
Date date2 = format.parse(time2);

Calendar cal=Calendar.getInstance();
cal.setTime(date2);
cal.add(Calendar.MINUTE, -30); //Subtract 30 Min

String strLong= format.format(cal.getTime());
textView4.setText(strLong);