Timezone conversion

Question

I need to convert from one timezone to another timezone in my project.

I am able to convert from my current timezone to another but not from a different timezone to

Answer 1

here a story: my user in US enters a date in a web page. My server gets this as a java.util.Date object. Date objects have no notion of time zone.

so let's say user entered 11PM(== 4AM london time). For her this was 11PM US time. Your server gets this and interprets this as 11PM of JVM's timezone. but what you need is a Date object that represents 4AM.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String timeStringInUS =  sdf.format("2020-05-04 23:00:00");

SimpleDateFormat dateFormatInUS = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
SimpleDateFormat dateFormatInUK = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

dateFormatInUS.setTimeZone(TimeZone.getTimeZone("America/New_York"));
dateFormatInUK.setTimeZone(TimeZone.getTimeZone("Europe/London"));

Date dateInUS = dateFormatInUS.parse(timeStringInUS);
Date dateInUK = sdf.parse(dateFormatInUK.format(dateInUS));