How to Convert Java Date to XML DateTime String?

// Java program to Convert Java Date to XML DateTime String

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class GFG {

    public static void main(String[] args)
    {

        // formatting time
        SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
        SimpleDateFormat format2 = new SimpleDateFormat("HH:mm:ss");
      
        // create a StringBuffer(in order to use its append
        // functionality) to store the date in XML DateTime
        // format
        StringBuffer buff = new StringBuffer();
      
        // get the date of the system by creating an
        // instance of the Date class
        Date date = new Date();
      
        // append the formatted date(yyyy-MM-dd) in the
        // buffer
        buff.append(format1.format(date));
      
        // append T
        buff.append('T');
      
        // and finally append the formatted time(HH:mm:ss) in
        // buffer
        buff.append(format2.format(date));

        // calculating time zone
        // get the calendar instance in order to get the
        // time offset
        Calendar calendar = Calendar.getInstance();
      
        // The get(int field_value) method of Calendar class
        // is used to return the value of the given calendar
        // field in the parameter.
        int offset = calendar.get(calendar.ZONE_OFFSET)
                     / (1000 * 60);
      
        // add the sign(+/-) according to the value of the
        // offset
        if (offset < 0) {
            buff.append('-');
          
            // if the offset is negative make it positive by
            // multiplying it with -1, we will be using it
            //further
            offset *= -1;
        }
        else {
            buff.append('+');
        }

        // get the hour from the offset and store it in a
        // String
        String s1 = String.valueOf(offset / 60);
      
        // check if the retrieved hour is single digit or
        // two digit in case of single digit, add 0 before
        // the significant value
        for (int i = s1.length(); i < 2; i++) {
            buff.append('0');
        }
      
        // then finally append the s1 in our buffer
        buff.append(s1);
        buff.append(':');

        // now retrieve the minutes from offset, and
        // validate it in the same way as we did for the hour
        String s2 = String.valueOf(offset % 60);
      
        for (int i = s2.length(); i < 2; i++) {
            buff.append('0');
        }
      
        // append the minutes in buffer
        buff.append(s2);
      
        // finally we are done formatting the Java Date time
        // into XML DateTime format convert the buffer into
        // the String, and print it
        System.out.println(buff.toString());
    }
}