Here you can find the source of addDay(long dateTimeMillis)
public static long addDay(long dateTimeMillis)
//package com.java2s; import java.util.Calendar; import java.util.GregorianCalendar; public class Main { public static long addDay(long dateTimeMillis) { Calendar calendar = new GregorianCalendar(); calendar.setTimeInMillis(dateTimeMillis); calendar.add(Calendar.DATE, 1); return calendar.getTimeInMillis(); }// w w w . ja va2 s . c o m }