Here you can find the source of addMonth(Calendar c, int months)
public static Date addMonth(Calendar c, int months)
//package com.java2s; import java.util.Calendar; import java.util.Date; public class Main { public static Date addMonth(Calendar c, int months) { if (c == null) return null; c.add(Calendar.MONTH, months); return c.getTime(); }/* w ww .ja v a 2 s . c o m*/ }