Many times we get the issue to convert String to date or convert date from timezone to date of other timezone. Below is one way to get through such issues, I will cover some parts of Joda DateTime & other formats from SimpleDateFormat.

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.TimeZone;

import javax.xml.datatype.DatatypeFactory;
import javax.xml.datatype.XMLGregorianCalendar;

public class Conversions {

 public static void main(String[] args) {
  System.out.println("UTC Date String : " +
    toUTCString(new Date()));
  
  System.out.println("UTC Date : " +
  toUTCDate(new Date()));

  Date date = getDate(toUTCString(new Date()));
  System.out.println("Date from String : " + date);

  System.out.println("Date for TimeZone : " +
  toTimeZone(date, TimeZone.getTimeZone("Europe/Copenhagen")));
  System.out.println("Date for TimeZone : " +
  toTimeZone(date, TimeZone.getTimeZone("US/Alaska")));

  getTimeZonesList();

  //  Converting UTC date string to Date
  System.out.println("UTC Date from UTC Date String : " +
  toUTCString(getDate("Mon Dec 15 21:45:55 UTC 2014")));
 }

 /**
  * Converts given date to UTC date String
  * @param date
  * @return String
  */
 public static String toUTCString(Date date){

  SimpleDateFormat dateFormatter = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
  final TimeZone utc = TimeZone.getTimeZone("UTC");
  dateFormatter.setTimeZone(utc);

  return dateFormatter.format(date);
 }

 /**
  * Converts given date to UTC date
  * @param date
  * @return Date
  */
 public static Date toUTCDate(Date date){

  SimpleDateFormat dateFormatter = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
  TimeZone.setDefault(TimeZone.getTimeZone("UTC"));
  dateFormatter.setTimeZone(TimeZone.getDefault());

  try {
   return dateFormatter.parse(dateFormatter.format(date));
  } catch (ParseException e) {
   e.printStackTrace();
  }
  return null;
 }

 /**
  * Coverts given date to date String in the given timezone
  * @param date
  * @param tz
  * @return String
  */
 public static String toTimeZone(Date date, final TimeZone tz){
  SimpleDateFormat dateFormatter = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
  dateFormatter.setTimeZone(tz);

  return dateFormatter.format(date);
 }

 /**
  * Converts given date String to the Date type Object
  * @param date
  * @return Date
  */
 public static Date getDate(String date){
  SimpleDateFormat dateFormatter = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
  try {
   return dateFormatter.parse(date);
  } catch (ParseException e) {
   e.printStackTrace();
  }

  return null;
 }

 /**
  * Returns the list of available TimeZone IDs supported
  * @return List<String>
  */
 public static List<String> getTimeZonesList(){
  List<String> ids = new ArrayList<>();

  String[] temp = TimeZone.getAvailableIDs();

  for(String id : temp){
   ids.add(id);
  }
  return Collections.unmodifiableList(ids);
 }
 
 /**
  * Converts XML Date to Util date format.
  *
  * @param XMLGregorianCalendar
  * @return java.util.Date
  */
  public static java.util.Date convertXMLDateToUtildate(
  final XMLGregorianCalendar date) {
  java.util.Date utilDate = null;
  TimeZone.setDefault(TimeZone.getTimeZone("UTC"));
  if (date != null) {
  utilDate = date.toGregorianCalendar().getTime();
  }
  return utilDate;

  }

  /**
  * Converts date to XMLGregorianCalendar specific to collateral reply source
  * system.
  *
  * @param date
  * @return gregorianDate
  * @throws Exception
  */
  public static XMLGregorianCalendar convertToXMLGregorianDateFormat(
  final java.util.Date date) throws Exception {
  DatatypeFactory df = DatatypeFactory.newInstance();
  GregorianCalendar gc = new GregorianCalendar();
  // gc.setTimeZone(TimeZone.getTimeZone("UTC"));
  gc.setTimeInMillis(date.getTime());
  return df.newXMLGregorianCalendar(gc);
  }
}