How can I convert an Integer (e.g 19000101 ) to java.util.Date?

Question

Here's my code:

Integer value = 19000101;         

How can I convert the above Integer represented in YYYYMMDD format to YYYY-MM-DD format in java.util.Date?

Answer 1

First you have to parse your format into date object using formatter specified

Integer value = 19000101;
SimpleDateFormat originalFormat = new SimpleDateFormat("yyyyMMdd");
Date date = originalFormat.parse(value.toString());

Remember that Date has no format. It just represents specific instance in time in milliseconds starting from 1970-01-01. But if you want to format that date to your expected format, you can use another formatter.

SimpleDateFormat newFormat = new SimpleDateFormat("yyyy-MM-dd");
String formatedDate = newFormat.format(date);

Now your formatedDate String should contain string that represent date in format yyyy-MM-dd

Answer 2

It seems to me that you don't really have a number representing your date, you have a string of three numbers: year, month, and day. You can extract those values with some simple arithmetic.

Integer value = 19000101;
int year = value / 10000;
int month = (value % 10000) / 100;
int day = value % 100;
Date date = new GregorianCalendar(year, month, day).getTime();