Here you can find the source of daysSinceTheJesus(Calendar cal)
public static long daysSinceTheJesus(Calendar cal)
//package com.java2s; /******************************************************************************* * Breakout Cave Survey Visualizer/*from www . j a v a 2 s . c om*/ * * Copyright (C) 2014 James Edwards * * jedwards8 at fastmail dot fm * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *******************************************************************************/ import java.util.Calendar; public class Main { public static long daysSinceTheJesus(Calendar cal) { long year = cal.get(Calendar.YEAR); long dayOfYear = cal.get(Calendar.DAY_OF_YEAR); return year * 365 + (year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400 + dayOfYear - 1; } }