Convert DateTime Using Java

import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.SimpleTimeZone;
import java.util.TimeZone;


public class ConvertDateTime {
 
 public static TimeZone tzGMT = TimeZone.getTimeZone("GMT0");
 public static TimeZone tzEL = TimeZone.getTimeZone("Europe/London");
 
 /*
                       *converts the system time to GMT
                      */
 public static Timestamp currentTimeInGMT() {
      DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      Date date = new Date();
      DateFormat firstFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      DateFormat secondFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      TimeZone firstTime = TimeZone.getTimeZone(dateFormat.format(date));
      firstFormat.setTimeZone(firstTime);
      //secondFormat.setTimeZone(secondTime);
      System.out.println("Current date and time: "+dateFormat.format(date));
      System.out.println("Time in GMT: ");
                                                                   // System.out.println("Time in GMT: "+ firstFormat.format(date)   +" GMT");
   return Timestamp.valueOf(firstFormat.format(date));
      }
                     /*
                       *converts the system time to BST
                      */

 public static Timestamp currentTimeInBST() {
      DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      Date date = new Date();
      DateFormat firstFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      DateFormat secondFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
      TimeZone firstTime = TimeZone.getTimeZone(dateFormat.format(date));
      TimeZone secondTime = tzEL;
      firstFormat.setTimeZone(firstTime);
      secondFormat.setTimeZone(secondTime);
      System.out.println("Current date and time: "+dateFormat.format(date));
      System.out.println("Time in GMT: " + firstFormat.format(date)+" GMT");
      System.out.println("Time in BST: "+ secondFormat.format(date)+" BST");
   return Timestamp.valueOf(secondFormat.format(date));
      }
    
 /*
                       *converts the time BST to GMT
                      */

 public static synchronized Timestamp BSTtoGMT(Date bstTime){
   String bstStr = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(bstTime); 
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
   sdf.setTimeZone(tzEL);
   Date gmtDate=null;
   try {  
    gmtDate =sdf.parse(bstStr);
    //System.out.println(gmtDate);
   } catch (ParseException e) {   
    e.printStackTrace();
   }
   Timestamp ts = new Timestamp(gmtDate.getTime());
   return ts;
   }
                      /*
                       *converts the time GMT to BST
                      */

 
 public static synchronized Timestamp GMTtoBST(Timestamp gmtTime){
  String gmtStr = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(gmtTime);  
  // SORT date is always in BST
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
  sdf.setTimeZone(tzGMT);
  Date bstDate=null;
  try {
   bstDate = sdf.parse(gmtStr);
   //System.out.println(bstDate);
  } catch (ParseException e) {   
   e.printStackTrace();
  }
  Timestamp ts = new Timestamp(bstDate.getTime());
  return ts;
 }
 
}