Java tutorial
//package com.java2s; import java.util.Calendar; import java.util.GregorianCalendar; public class Main { public static int getWeekOfYear(String year, String month, String day) { Calendar cal = new GregorianCalendar(); cal.clear(); cal.set(new Integer(year).intValue(), new Integer(month).intValue() - 1, new Integer(day).intValue()); return cal.get(Calendar.WEEK_OF_YEAR); } }