Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed 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.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class Main {
    /**
     * Given a calendar (possibly containing only a day of the year), returns the earliest possible
     * anniversary of the date that is equal to or after the current point in time if the date
     * does not contain a year, or the date converted to the local time zone (if the date contains
     * a year.
     *
     * @param target The date we wish to convert(in the UTC time zone).
     * @return If date does not contain a year (year < 1900), returns the next earliest anniversary
     * that is after the current point in time (in the local time zone). Otherwise, returns the
     * adjusted Date in the local time zone.
     */
    public static Date getNextAnnualDate(Calendar target) {
        final Calendar today = Calendar.getInstance();
        today.setTime(new Date());

        // Round the current time to the exact start of today so that when we compare
        // today against the target date, both dates are set to exactly 0000H.
        today.set(Calendar.HOUR_OF_DAY, 0);
        today.set(Calendar.MINUTE, 0);
        today.set(Calendar.SECOND, 0);
        today.set(Calendar.MILLISECOND, 0);

        final boolean isYearSet = isYearSet(target);
        final int targetYear = target.get(Calendar.YEAR);
        final int targetMonth = target.get(Calendar.MONTH);
        final int targetDay = target.get(Calendar.DAY_OF_MONTH);
        final boolean isFeb29 = (targetMonth == Calendar.FEBRUARY && targetDay == 29);
        final GregorianCalendar anniversary = new GregorianCalendar();
        // Convert from the UTC date to the local date. Set the year to today's year if the
        // there is no provided year (targetYear < 1900)
        anniversary.set(!isYearSet ? today.get(Calendar.YEAR) : targetYear, targetMonth, targetDay);
        // If the anniversary's date is before the start of today and there is no year set,
        // increment the year by 1 so that the returned date is always equal to or greater than
        // today. If the day is a leap year, keep going until we get the next leap year anniversary
        // Otherwise if there is already a year set, simply return the exact date.
        if (!isYearSet) {
            int anniversaryYear = today.get(Calendar.YEAR);
            if (anniversary.before(today) || (isFeb29 && !anniversary.isLeapYear(anniversaryYear))) {
                // If the target date is not Feb 29, then set the anniversary to the next year.
                // Otherwise, keep going until we find the next leap year (this is not guaranteed
                // to be in 4 years time).
                do {
                    anniversaryYear += 1;
                } while (isFeb29 && !anniversary.isLeapYear(anniversaryYear));
                anniversary.set(anniversaryYear, targetMonth, targetDay);
            }
        }
        return anniversary.getTime();
    }

    public static boolean isYearSet(Calendar cal) {
        // use the Calendar.YEAR field to track whether or not the year is set instead of
        // Calendar.isSet() because doing Calendar.get() causes Calendar.isSet() to become
        // true irregardless of what the previous value was
        return cal.get(Calendar.YEAR) > 1;
    }
}