Here you can find the source of getAgeOfCalendar(String birthDayString)
public static int getAgeOfCalendar(String birthDayString) throws Exception
//package com.java2s; /*/* w w w . ja va 2s . c o m*/ * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class Main { public static int getAgeOfCalendar(String birthDayString) throws Exception { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); Date birthDay = df.parse(birthDayString); Calendar cal = Calendar.getInstance(); int yearNow = cal.get(Calendar.YEAR); int monthNow = cal.get(Calendar.MONTH); int dayOfMonthNow = cal.get(Calendar.DAY_OF_MONTH); cal.setTime(birthDay); int yearBirth = cal.get(Calendar.YEAR); int monthBirth = cal.get(Calendar.MONTH); int dayOfMonthBirth = cal.get(Calendar.DAY_OF_MONTH); int age = yearNow - yearBirth; if (monthNow < monthBirth || (monthNow == monthBirth && dayOfMonthNow < dayOfMonthBirth)) { age--; } return age; } }