Answer Posted / manoj kumar

public class DateUtil implements Serializable,Cloneable {

   private static volatile Dateutil instance;

   private DateUtil() {
     //no-op
   }

   public static DateUtil getInstance() {

      if(instance==null) {
        synchronized(DateUtil.this) {
           if(instance==null) {
              instance = new DateUtil();
           }
        }
        return instance;
      }
   
   protected Object readResolve() {
     return instance;
   }

   public Object clone() throws CloneNotSupportedException {

     super.clone();

     throw new CloneNotSupportedException;
  }

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