Java tutorial
//package com.java2s; import java.util.Calendar; import java.util.Date; public class Main { public static int getUpMonth(Date date) { Calendar c = Calendar.getInstance(); c.setTime(date); c.add(Calendar.MONTH, -1); return c.get(Calendar.MONTH); } public static int getUpMonth() { return getUpMonth(new Date()); } public static Date add(Date date, int field, int amount) { Calendar c = Calendar.getInstance(); c.setTime(date); c.add(field, amount); return c.getTime(); } }