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POJava DateTime is a simple, light-weight Java-based API for parsing and manipulating dates. It parses dates from most languages and formats out of the box without having to specify which format is expected. Defaults such as time zones, and whether to interpret an internationally ambiguous date like "03/06/2014" as DMY order or MDY order are inferred by system time zone and locale and stored in a default config object that can be replaced or overridden. Multiple languages for month names are supported without any additional configuration needed. This is a forked version edited by Jianlin

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package org.pojava.datetime;

import java.text.DateFormatSymbols;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

/**
 * This is a language-agnostic mapping of month abbreviations to month numbers
 */
public class MonthMap {

    private Map monthMap = new HashMap();

    public MonthMap() {
    }

    public static MonthMap fromAllLocales() {
        MonthMap newMonthMap = new MonthMap();
        Locale[] locales = DateFormatSymbols.getAvailableLocales();
        for (Locale locale : locales) {
            DateFormatSymbols dfs = DateFormatSymbols.getInstance(locale);
            String[] longMonths = dfs.getMonths();
            String[] shortMonths = dfs.getShortMonths();
            for (int i = 0; i < 12; i++) {
                String shortMonth = shortMonths[i].toUpperCase();
                String shortMonth4 = shortMonths[i].toUpperCase().substring(0, Math.min(4, shortMonths[i].length()));
                String longMonth = longMonths[i].toUpperCase();
                if (longMonth.startsWith(shortMonth4) || shortMonth4.endsWith(".")) {
                    // If a truncated month name matches its 4-char abbrev, we'll use it.
                    // The goal is to support both standard and non-standard abbreviations like "Octob".
                    newMonthMap.addMonth(shortMonth4, i);
                    // Finland's 11th month starts with "MAR" which collides with EN on 3-char abbrevs.
                    // Except for that, we'll recognize 3-char abbreviations
                    if (shortMonth4.length() == 4 && !locale.toString().startsWith("fi")) {
                        newMonthMap.addMonth(shortMonth.substring(0, 3), i);
                    }
                } else {
                    // Otherwise, we'll strictly match the abbreviation and full name
                    newMonthMap.addMonth(shortMonth, i);
                    newMonthMap.addMonth(longMonth, i);
                }
            }
        }
        return newMonthMap;
    }

    /**
     * Returns a multi-language lookup based on the first 3 or 4 characters of a month
     *
     * @param candidateMonth A word whose first 3 or 4 letters match any known month abbreviation
     * @return null if no match found, or an Integer between 1 and 12
     */
    public Integer monthIndex(String candidateMonth) {
        if (candidateMonth == null) {
            return null;
        }
        candidateMonth = candidateMonth.toUpperCase();
        // First, try for an exact match
        Integer monthIndex = monthMap.get(candidateMonth);
        // If no match, try an abbrev of four characters if possible
        if (monthIndex == null && candidateMonth.length() > 4) {
            monthIndex = monthMap.get(candidateMonth.substring(0, 4));
        }
        // If still no match, truncate to 3 characters and retry
        // Consider where candidateMonth="DEC." and abbrev="DEC".
        if (monthIndex == null && candidateMonth.length() > 3) {
            monthIndex = monthMap.get(candidateMonth.substring(0, 3));
        }
        return monthIndex;
    }

    /**
     * Registers a new month abbreviation.  Will ignore duplicates.
     *
     * @param abbrev      Month abbreviation (must be either 3 or 4 characters)
     * @param monthNumber In range 1..12
     */
    public void addMonth(String abbrev, Integer monthNumber) {
        abbrev = abbrev.toUpperCase();
        if (!monthMap.containsKey(abbrev)) {
            monthMap.put(abbrev, monthNumber);
        }
    }

    public boolean isEmpty() {
        return monthMap == null || monthMap.isEmpty();
    }
}