How to estimate execution time of a method using Java Reflection?

import java.lang.reflect.*;
       
   public class CustomeMath{
     public int addMe(int a, int b)
      {
         return a + b;
      }
        
      public static void main(String args[])
      {
         try {
           Class cls = Class.forName("CustomeMath");
           Class partypes[] = new Class[2];
            partypes[0] = Integer.TYPE;
            partypes[1] = Integer.TYPE;
            Method meth = cls.getMethod(
              "addMe", partypes);
            CustomeMath methobj = new CustomeMath();
            Object arglist[] = new Object[2];
            arglist[0] = new Integer(37);
            arglist[1] = new Integer(47);
            Object retobj 
              = meth.invoke(methobj, arglist);
            Integer retval = (Integer)retobj;
            System.out.println(retval.intValue());
         }
         catch (Throwable e) {
            System.err.println(e);         }
      }
   }