java - How to set the TimeZone for String parsing in Android

Question

I try to parse a String and set a time zone, but I can't produce the desired result.

String dtc = "2014-04-02T07:59:02.111Z";
SimpleDateFormat readDate = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
Date date = null;
try {
   date = readDate.parse(dtc);
   Log.d("myLog", "date "+date);
} catch (ParseException e) {
   Log.d("myLog", "dateExcep " + e);
}

SimpleDateFormat writeDate = new SimpleDateFormat("dd.MM.yyyy, HH.mm"); 
writeDate.setTimeZone(TimeZone.getTimeZone("GMT+04:00"));
String dateString = writeDate.format(date);

At the output of the variable "dateString" still gives the time 07:59:02 , and I want to make it +4 hours in advance that is 11:59:02

Answer 1

You need to instruct the read-formatter to interprete the input as UTC (GMT - remember that Z stands for UTC in ISO-8601-format):

String dtc = "2014-04-02T07:59:02.111Z";
SimpleDateFormat readDate = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
readDate.setTimeZone(TimeZone.getTimeZone("GMT")); // missing line
Date date = readDate.parse(dtc);
SimpleDateFormat writeDate = new SimpleDateFormat("dd.MM.yyyy, HH.mm");
writeDate.setTimeZone(TimeZone.getTimeZone("GMT+04:00"));
String s = writeDate.format(date);

Then you will get:

02.04.2014, 11.59