Java Date Add add(Date date, int calendarField, int amount)

Description

Adds to a date returning a new object.

License

Apache License

Parameter

Parameter	Description
date	the date, not null
calendarField	the calendar field to add to
amount	the amount to add, may be negative

Exception

Parameter	Description
IllegalArgumentException	if the date is null

Return

the new Date with the amount added

Declaration

private static Date add(Date date, int calendarField, int amount) 

Method Source Code

//package com.java2s;
/*//  w  w w.jav  a2  s  .  c om
 * 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.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Main {
    /**
     * Adds to a date returning a new object. The original {@code Date} is
     * unchanged.
     * 
     * @param date
     *            the date, not null
     * @param calendarField
     *            the calendar field to add to
     * @param amount
     *            the amount to add, may be negative
     * @return the new {@code Date} with the amount added
     * @throws IllegalArgumentException
     *             if the date is null
     */
    private static Date add(Date date, int calendarField, int amount) {
        if (date == null) {
            throw new IllegalArgumentException("The date must not be null");
        }
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.add(calendarField, amount);
        return c.getTime();
    }

    public static long getTime(String date, String pattern) {
        try {
            return parseDate(date, pattern).getTime();
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return 0;
    }

    /**
     * <p>
     * Parses a string representing a date by trying a variety of different
     * parsers.
     * </p>
     * 
     * <p>
     * The parse will try each parse pattern in turn. A parse is only deemed
     * successful if it parses the whole of the input string. If no parse
     * patterns match, a ParseException is thrown.
     * </p>
     * The parser will be lenient toward the parsed date.
     * 
     * @param str
     *            the date to parse, not null
     * @param parsePatterns
     *            the date format patterns to use, see SimpleDateFormat, not
     *            null
     * @return the parsed date
     * @throws IllegalArgumentException
     *             if the date string or pattern array is null
     * @throws ParseException
     *             if none of the date patterns were suitable (or there were
     *             none)
     */
    public static Date parseDate(String str, String... parsePatterns) throws ParseException {
        return parseDateWithLeniency(str, parsePatterns, true);
    }

    /**
     * <p>
     * Parses a string representing a date by trying a variety of different
     * parsers.
     * </p>
     * 
     * <p>
     * The parse will try each parse pattern in turn. A parse is only deemed
     * successful if it parses the whole of the input string. If no parse
     * patterns match, a ParseException is thrown.
     * </p>
     * 
     * @param str
     *            the date to parse, not null
     * @param parsePatterns
     *            the date format patterns to use, see SimpleDateFormat, not
     *            null
     * @param lenient
     *            Specify whether or not date/time parsing is to be lenient.
     * @return the parsed date
     * @throws IllegalArgumentException
     *             if the date string or pattern array is null
     * @throws ParseException
     *             if none of the date patterns were suitable
     * @see java.util.Calender#isLenient()
     */
    private static Date parseDateWithLeniency(String str, String[] parsePatterns, boolean lenient)
            throws ParseException {
        if (str == null || parsePatterns == null) {
            throw new IllegalArgumentException("Date and Patterns must not be null");
        }

        SimpleDateFormat parser = new SimpleDateFormat();
        parser.setLenient(lenient);
        ParsePosition pos = new ParsePosition(0);
        for (String parsePattern : parsePatterns) {

            String pattern = parsePattern;

            // LANG-530 - need to make sure 'ZZ' output doesn't get passed to
            // SimpleDateFormat
            if (parsePattern.endsWith("ZZ")) {
                pattern = pattern.substring(0, pattern.length() - 1);
            }

            parser.applyPattern(pattern);
            pos.setIndex(0);

            String str2 = str;
            // LANG-530 - need to make sure 'ZZ' output doesn't hit
            // SimpleDateFormat as it will ParseException
            if (parsePattern.endsWith("ZZ")) {
                str2 = str.replaceAll("([-+][0-9][0-9]):([0-9][0-9])$", "$1$2");
            }

            Date date = parser.parse(str2, pos);
            if (date != null && pos.getIndex() == str2.length()) {
                return date;
            }
        }
        throw new ParseException("Unable to parse the date: " + str, -1);
    }
}

Related

1. add(Date actual, Integer type, Integer count)
2. add(Date date, int calendarField, int amount)
3. add(Date date, int calendarField, int amount)
4. add(Date date, int field, int amount)
5. add(Date date, int field, int amount)
6. add(Date date, int field, int diff)