Here you can find the source of addDay(Date date, int days)
public static final Date addDay(Date date, int days)
//package com.java2s; //License from project: Open Source License import java.util.*; public class Main { public static final Date addDay(Date date, int days) { Calendar cale = Calendar.getInstance(); cale.setTime(date);//from ww w. j a v a 2 s . com cale.add(Calendar.DAY_OF_YEAR, days); return cale.getTime(); } }