Currency.java

/*
 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * accompanied this code).
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.util;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileReader;
import java.io.InputStream;
import java.io.IOException;
import java.io.Serializable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
import java.util.spi.CurrencyNameProvider;
import java.util.stream.Collectors;

import jdk.internal.util.StaticProperty;
import sun.util.locale.provider.CalendarDataUtility;
import sun.util.locale.provider.LocaleServiceProviderPool;
import sun.util.logging.PlatformLogger;


/**
 * Represents a currency. Currencies are identified by their ISO 4217 currency
 * codes. Visit the <a href="http://www.iso.org/iso/home/standards/currency_codes.htm">
 * ISO web site</a> for more information.
 * <p>
 * The class is designed so that there's never more than one
 * <code>Currency</code> instance for any given currency. Therefore, there's
 * no public constructor. You obtain a <code>Currency</code> instance using
 * the <code>getInstance</code> methods.
 * <p>
 * Users can supersede the Java runtime currency data by means of the system
 * property {@code java.util.currency.data}. If this system property is
 * defined then its value is the location of a properties file, the contents of
 * which are key/value pairs of the ISO 3166 country codes and the ISO 4217
 * currency data respectively.  The value part consists of three ISO 4217 values
 * of a currency, i.e., an alphabetic code, a numeric code, and a minor unit.
 * Those three ISO 4217 values are separated by commas.
 * The lines which start with '#'s are considered comment lines. An optional UTC
 * timestamp may be specified per currency entry if users need to specify a
 * cutover date indicating when the new data comes into effect. The timestamp is
 * appended to the end of the currency properties and uses a comma as a separator.
 * If a UTC datestamp is present and valid, the JRE will only use the new currency
 * properties if the current UTC date is later than the date specified at class
 * loading time. The format of the timestamp must be of ISO 8601 format :
 * {@code 'yyyy-MM-dd'T'HH:mm:ss'}. For example,
 * <p>
 * <code>
 * #Sample currency properties<br>
 * JP=JPZ,999,0
 * </code>
 * <p>
 * will supersede the currency data for Japan. If JPZ is one of the existing
 * ISO 4217 currency code referred by other countries, the existing
 * JPZ currency data is updated with the given numeric code and minor
 * unit value.
 *
 * <p>
 * <code>
 * #Sample currency properties with cutover date<br>
 * JP=JPZ,999,0,2014-01-01T00:00:00
 * </code>
 * <p>
 * will supersede the currency data for Japan if {@code Currency} class is loaded after
 * 1st January 2014 00:00:00 GMT.
 * <p>
 * Where syntactically malformed entries are encountered, the entry is ignored
 * and the remainder of entries in file are processed. For instances where duplicate
 * country code entries exist, the behavior of the Currency information for that
 * {@code Currency} is undefined and the remainder of entries in file are processed.
 * <p>
 * If multiple property entries with same currency code but different numeric code
 * and/or minor unit are encountered, those entries are ignored and the remainder
 * of entries in file are processed.
 *
 * <p>
 * It is recommended to use {@link java.math.BigDecimal} class while dealing
 * with {@code Currency} or monetary values as it provides better handling of floating
 * point numbers and their operations.
 *
 * @see java.math.BigDecimal
 * @since 1.4
 */
public final class Currency implements Serializable {

    private static final long serialVersionUID = -158308464356906721L;

    /**
     * ISO 4217 currency code for this currency.
     *
     * @serial
     */
    private final String currencyCode;

    /**
     * Default fraction digits for this currency.
     * Set from currency data tables.
     */
    private final transient int defaultFractionDigits;

    /**
     * ISO 4217 numeric code for this currency.
     * Set from currency data tables.
     */
    private final transient int numericCode;


    // class data: instance map

    private static ConcurrentMap<String, Currency> instances = new ConcurrentHashMap<>(7);
    private static HashSet<Currency> available;

    // Class data: currency data obtained from currency.data file.
    // Purpose:
    // - determine valid country codes
    // - determine valid currency codes
    // - map country codes to currency codes
    // - obtain default fraction digits for currency codes
    //
    // sc = special case; dfd = default fraction digits
    // Simple countries are those where the country code is a prefix of the
    // currency code, and there are no known plans to change the currency.
    //
    // table formats:
    // - mainTable:
    //   - maps country code to 32-bit int
    //   - 26*26 entries, corresponding to [A-Z]*[A-Z]
    //   - \u007F -> not valid country
    //   - bits 20-31: unused
    //   - bits 10-19: numeric code (0 to 1023)
    //   - bit 9: 1 - special case, bits 0-4 indicate which one
    //            0 - simple country, bits 0-4 indicate final char of currency code
    //   - bits 5-8: fraction digits for simple countries, 0 for special cases
    //   - bits 0-4: final char for currency code for simple country, or ID of special case
    // - special case IDs:
    //   - 0: country has no currency
    //   - other: index into specialCasesList

    static int formatVersion;
    static int dataVersion;
    static int[] mainTable;
    static List<SpecialCaseEntry> specialCasesList;
    static List<OtherCurrencyEntry> otherCurrenciesList;

    // handy constants - must match definitions in GenerateCurrencyData
    // magic number
    private static final int MAGIC_NUMBER = 0x43757244;
    // number of characters from A to Z
    private static final int A_TO_Z = ('Z' - 'A') + 1;
    // entry for invalid country codes
    private static final int INVALID_COUNTRY_ENTRY = 0x0000007F;
    // entry for countries without currency
    private static final int COUNTRY_WITHOUT_CURRENCY_ENTRY = 0x00000200;
    // mask for simple case country entries
    private static final int SIMPLE_CASE_COUNTRY_MASK = 0x00000000;
    // mask for simple case country entry final character
    private static final int SIMPLE_CASE_COUNTRY_FINAL_CHAR_MASK = 0x0000001F;
    // mask for simple case country entry default currency digits
    private static final int SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_MASK = 0x000001E0;
    // shift count for simple case country entry default currency digits
    private static final int SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT = 5;
    // maximum number for simple case country entry default currency digits
    private static final int SIMPLE_CASE_COUNTRY_MAX_DEFAULT_DIGITS = 9;
    // mask for special case country entries
    private static final int SPECIAL_CASE_COUNTRY_MASK = 0x00000200;
    // mask for special case country index
    private static final int SPECIAL_CASE_COUNTRY_INDEX_MASK = 0x0000001F;
    // delta from entry index component in main table to index into special case tables
    private static final int SPECIAL_CASE_COUNTRY_INDEX_DELTA = 1;
    // mask for distinguishing simple and special case countries
    private static final int COUNTRY_TYPE_MASK = SIMPLE_CASE_COUNTRY_MASK | SPECIAL_CASE_COUNTRY_MASK;
    // mask for the numeric code of the currency
    private static final int NUMERIC_CODE_MASK = 0x000FFC00;
    // shift count for the numeric code of the currency
    private static final int NUMERIC_CODE_SHIFT = 10;

    // Currency data format version
    private static final int VALID_FORMAT_VERSION = 3;

    static {
        AccessController.doPrivileged(new PrivilegedAction<>() {
            @Override
            public Void run() {
                try {
                    try (InputStream in = getClass().getResourceAsStream("/java/util/currency.data")) {
                        if (in == null) {
                            throw new InternalError("Currency data not found");
                        }
                        DataInputStream dis = new DataInputStream(new BufferedInputStream(in));
                        if (dis.readInt() != MAGIC_NUMBER) {
                            throw new InternalError("Currency data is possibly corrupted");
                        }
                        formatVersion = dis.readInt();
                        if (formatVersion != VALID_FORMAT_VERSION) {
                            throw new InternalError("Currency data format is incorrect");
                        }
                        dataVersion = dis.readInt();
                        mainTable = readIntArray(dis, A_TO_Z * A_TO_Z);
                        int scCount = dis.readInt();
                        specialCasesList = readSpecialCases(dis, scCount);
                        int ocCount = dis.readInt();
                        otherCurrenciesList = readOtherCurrencies(dis, ocCount);
                    }
                } catch (IOException e) {
                    throw new InternalError(e);
                }

                // look for the properties file for overrides
                String propsFile = System.getProperty("java.util.currency.data");
                if (propsFile == null) {
                    propsFile = StaticProperty.javaHome() + File.separator + "lib" +
                        File.separator + "currency.properties";
                }
                try {
                    File propFile = new File(propsFile);
                    if (propFile.exists()) {
                        Properties props = new Properties();
                        try (FileReader fr = new FileReader(propFile)) {
                            props.load(fr);
                        }
                        Pattern propertiesPattern =
                                Pattern.compile("([A-Z]{3})\\s*,\\s*(\\d{3})\\s*,\\s*" +
                                        "(\\d+)\\s*,?\\s*(\\d{4}-\\d{2}-\\d{2}T\\d{2}:" +
                                        "\\d{2}:\\d{2})?");
                        List<CurrencyProperty> currencyEntries
                                = getValidCurrencyData(props, propertiesPattern);
                        currencyEntries.forEach(Currency::replaceCurrencyData);
                    }
                } catch (IOException e) {
                    CurrencyProperty.info("currency.properties is ignored"
                            + " because of an IOException", e);
                }
                return null;
            }
        });
    }

    /**
     * Constants for retrieving localized names from the name providers.
     */
    private static final int SYMBOL = 0;
    private static final int DISPLAYNAME = 1;


    /**
     * Constructs a <code>Currency</code> instance. The constructor is private
     * so that we can insure that there's never more than one instance for a
     * given currency.
     */
    private Currency(String currencyCode, int defaultFractionDigits, int numericCode) {
        this.currencyCode = currencyCode;
        this.defaultFractionDigits = defaultFractionDigits;
        this.numericCode = numericCode;
    }

    /**
     * Returns the <code>Currency</code> instance for the given currency code.
     *
     * @param currencyCode the ISO 4217 code of the currency
     * @return the <code>Currency</code> instance for the given currency code
     * @exception NullPointerException if <code>currencyCode</code> is null
     * @exception IllegalArgumentException if <code>currencyCode</code> is not
     * a supported ISO 4217 code.
     */
    public static Currency getInstance(String currencyCode) {
        return getInstance(currencyCode, Integer.MIN_VALUE, 0);
    }

    private static Currency getInstance(String currencyCode, int defaultFractionDigits,
        int numericCode) {
        // Try to look up the currency code in the instances table.
        // This does the null pointer check as a side effect.
        // Also, if there already is an entry, the currencyCode must be valid.
        Currency instance = instances.get(currencyCode);
        if (instance != null) {
            return instance;
        }

        if (defaultFractionDigits == Integer.MIN_VALUE) {
            // Currency code not internally generated, need to verify first
            // A currency code must have 3 characters and exist in the main table
            // or in the list of other currencies.
            boolean found = false;
            if (currencyCode.length() != 3) {
                throw new IllegalArgumentException();
            }
            char char1 = currencyCode.charAt(0);
            char char2 = currencyCode.charAt(1);
            int tableEntry = getMainTableEntry(char1, char2);
            if ((tableEntry & COUNTRY_TYPE_MASK) == SIMPLE_CASE_COUNTRY_MASK
                    && tableEntry != INVALID_COUNTRY_ENTRY
                    && currencyCode.charAt(2) - 'A' == (tableEntry & SIMPLE_CASE_COUNTRY_FINAL_CHAR_MASK)) {
                defaultFractionDigits = (tableEntry & SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_MASK) >> SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT;
                numericCode = (tableEntry & NUMERIC_CODE_MASK) >> NUMERIC_CODE_SHIFT;
                found = true;
            } else { //special case
                int[] fractionAndNumericCode = SpecialCaseEntry.findEntry(currencyCode);
                if (fractionAndNumericCode != null) {
                    defaultFractionDigits = fractionAndNumericCode[0];
                    numericCode = fractionAndNumericCode[1];
                    found = true;
                }
            }

            if (!found) {
                OtherCurrencyEntry ocEntry = OtherCurrencyEntry.findEntry(currencyCode);
                if (ocEntry == null) {
                    throw new IllegalArgumentException();
                }
                defaultFractionDigits = ocEntry.fraction;
                numericCode = ocEntry.numericCode;
            }
        }

        Currency currencyVal =
            new Currency(currencyCode, defaultFractionDigits, numericCode);
        instance = instances.putIfAbsent(currencyCode, currencyVal);
        return (instance != null ? instance : currencyVal);
    }

    /**
     * Returns the <code>Currency</code> instance for the country of the
     * given locale. The language and variant components of the locale
     * are ignored. The result may vary over time, as countries change their
     * currencies. For example, for the original member countries of the
     * European Monetary Union, the method returns the old national currencies
     * until December 31, 2001, and the Euro from January 1, 2002, local time
     * of the respective countries.
     * <p>
     * If the specified {@code locale} contains "cu" and/or "rg"
     * <a href="./Locale.html#def_locale_extension">Unicode extensions</a>,
     * the instance returned from this method reflects
     * the values specified with those extensions. If both "cu" and "rg" are
     * specified, the currency from the "cu" extension supersedes the implicit one
     * from the "rg" extension.
     * <p>
     * The method returns <code>null</code> for territories that don't
     * have a currency, such as Antarctica.
     *
     * @param locale the locale for whose country a <code>Currency</code>
     * instance is needed
     * @return the <code>Currency</code> instance for the country of the given
     * locale, or {@code null}
     * @exception NullPointerException if <code>locale</code>
     * is {@code null}
     * @exception IllegalArgumentException if the country of the given {@code locale}
     * is not a supported ISO 3166 country code.
     */
    public static Currency getInstance(Locale locale) {
        // check for locale overrides
        String override = locale.getUnicodeLocaleType("cu");
        if (override != null) {
            try {
                return getInstance(override.toUpperCase(Locale.ROOT));
            } catch (IllegalArgumentException iae) {
                // override currency is invalid. Fall through.
            }
        }

        String country = CalendarDataUtility.findRegionOverride(locale).getCountry();

        if (country == null || !country.matches("^[a-zA-Z]{2}$")) {
            throw new IllegalArgumentException();
        }

        char char1 = country.charAt(0);
        char char2 = country.charAt(1);
        int tableEntry = getMainTableEntry(char1, char2);
        if ((tableEntry & COUNTRY_TYPE_MASK) == SIMPLE_CASE_COUNTRY_MASK
                    && tableEntry != INVALID_COUNTRY_ENTRY) {
            char finalChar = (char) ((tableEntry & SIMPLE_CASE_COUNTRY_FINAL_CHAR_MASK) + 'A');
            int defaultFractionDigits = (tableEntry & SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_MASK) >> SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT;
            int numericCode = (tableEntry & NUMERIC_CODE_MASK) >> NUMERIC_CODE_SHIFT;
            StringBuilder sb = new StringBuilder(country);
            sb.append(finalChar);
            return getInstance(sb.toString(), defaultFractionDigits, numericCode);
        } else {
            // special cases
            if (tableEntry == INVALID_COUNTRY_ENTRY) {
                throw new IllegalArgumentException();
            }
            if (tableEntry == COUNTRY_WITHOUT_CURRENCY_ENTRY) {
                return null;
            } else {
                int index = SpecialCaseEntry.toIndex(tableEntry);
                SpecialCaseEntry scEntry = specialCasesList.get(index);
                if (scEntry.cutOverTime == Long.MAX_VALUE
                        || System.currentTimeMillis() < scEntry.cutOverTime) {
                    return getInstance(scEntry.oldCurrency,
                            scEntry.oldCurrencyFraction,
                            scEntry.oldCurrencyNumericCode);
                } else {
                    return getInstance(scEntry.newCurrency,
                            scEntry.newCurrencyFraction,
                            scEntry.newCurrencyNumericCode);
                }
            }
        }
    }

    /**
     * Gets the set of available currencies.  The returned set of currencies
     * contains all of the available currencies, which may include currencies
     * that represent obsolete ISO 4217 codes.  The set can be modified
     * without affecting the available currencies in the runtime.
     *
     * @return the set of available currencies.  If there is no currency
     *    available in the runtime, the returned set is empty.
     * @since 1.7
     */
    public static Set<Currency> getAvailableCurrencies() {
        synchronized(Currency.class) {
            if (available == null) {
                available = new HashSet<>(256);

                // Add simple currencies first
                for (char c1 = 'A'; c1 <= 'Z'; c1 ++) {
                    for (char c2 = 'A'; c2 <= 'Z'; c2 ++) {
                        int tableEntry = getMainTableEntry(c1, c2);
                        if ((tableEntry & COUNTRY_TYPE_MASK) == SIMPLE_CASE_COUNTRY_MASK
                             && tableEntry != INVALID_COUNTRY_ENTRY) {
                            char finalChar = (char) ((tableEntry & SIMPLE_CASE_COUNTRY_FINAL_CHAR_MASK) + 'A');
                            int defaultFractionDigits = (tableEntry & SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_MASK) >> SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT;
                            int numericCode = (tableEntry & NUMERIC_CODE_MASK) >> NUMERIC_CODE_SHIFT;
                            StringBuilder sb = new StringBuilder();
                            sb.append(c1);
                            sb.append(c2);
                            sb.append(finalChar);
                            available.add(getInstance(sb.toString(), defaultFractionDigits, numericCode));
                        } else if ((tableEntry & COUNTRY_TYPE_MASK) == SPECIAL_CASE_COUNTRY_MASK
                                && tableEntry != INVALID_COUNTRY_ENTRY
                                && tableEntry != COUNTRY_WITHOUT_CURRENCY_ENTRY) {
                            int index = SpecialCaseEntry.toIndex(tableEntry);
                            SpecialCaseEntry scEntry = specialCasesList.get(index);

                            if (scEntry.cutOverTime == Long.MAX_VALUE
                                    || System.currentTimeMillis() < scEntry.cutOverTime) {
                                available.add(getInstance(scEntry.oldCurrency,
                                        scEntry.oldCurrencyFraction,
                                        scEntry.oldCurrencyNumericCode));
                            } else {
                                available.add(getInstance(scEntry.newCurrency,
                                        scEntry.newCurrencyFraction,
                                        scEntry.newCurrencyNumericCode));
                            }
                        }
                    }
                }

                // Now add other currencies
                for (OtherCurrencyEntry entry : otherCurrenciesList) {
                    available.add(getInstance(entry.currencyCode));
                }
            }
        }

        @SuppressWarnings("unchecked")
        Set<Currency> result = (Set<Currency>) available.clone();
        return result;
    }

    /**
     * Gets the ISO 4217 currency code of this currency.
     *
     * @return the ISO 4217 currency code of this currency.
     */
    public String getCurrencyCode() {
        return currencyCode;
    }

    /**
     * Gets the symbol of this currency for the default
     * {@link Locale.Category#DISPLAY DISPLAY} locale.
     * For example, for the US Dollar, the symbol is "$" if the default
     * locale is the US, while for other locales it may be "US$". If no
     * symbol can be determined, the ISO 4217 currency code is returned.
     * <p>
     * If the default {@link Locale.Category#DISPLAY DISPLAY} locale
     * contains "rg" (region override)
     * <a href="./Locale.html#def_locale_extension">Unicode extension</a>,
     * the symbol returned from this method reflects
     * the value specified with that extension.
     * <p>
     * This is equivalent to calling
     * {@link #getSymbol(Locale)
     *     getSymbol(Locale.getDefault(Locale.Category.DISPLAY))}.
     *
     * @return the symbol of this currency for the default
     *     {@link Locale.Category#DISPLAY DISPLAY} locale
     */
    public String getSymbol() {
        return getSymbol(Locale.getDefault(Locale.Category.DISPLAY));
    }

    /**
     * Gets the symbol of this currency for the specified locale.
     * For example, for the US Dollar, the symbol is "$" if the specified
     * locale is the US, while for other locales it may be "US$". If no
     * symbol can be determined, the ISO 4217 currency code is returned.
     * <p>
     * If the specified {@code locale} contains "rg" (region override)
     * <a href="./Locale.html#def_locale_extension">Unicode extension</a>,
     * the symbol returned from this method reflects
     * the value specified with that extension.
     *
     * @param locale the locale for which a display name for this currency is
     * needed
     * @return the symbol of this currency for the specified locale
     * @exception NullPointerException if <code>locale</code> is null
     */
    public String getSymbol(Locale locale) {
        LocaleServiceProviderPool pool =
            LocaleServiceProviderPool.getPool(CurrencyNameProvider.class);
        locale = CalendarDataUtility.findRegionOverride(locale);
        String symbol = pool.getLocalizedObject(
                                CurrencyNameGetter.INSTANCE,
                                locale, currencyCode, SYMBOL);
        if (symbol != null) {
            return symbol;
        }

        // use currency code as symbol of last resort
        return currencyCode;
    }

    /**
     * Gets the default number of fraction digits used with this currency.
     * Note that the number of fraction digits is the same as ISO 4217's
     * minor unit for the currency.
     * For example, the default number of fraction digits for the Euro is 2,
     * while for the Japanese Yen it's 0.
     * In the case of pseudo-currencies, such as IMF Special Drawing Rights,
     * -1 is returned.
     *
     * @return the default number of fraction digits used with this currency
    */
    public int getDefaultFractionDigits() {
        return defaultFractionDigits;
    }

    /**
     * Returns the ISO 4217 numeric code of this currency.
     *
     * @return the ISO 4217 numeric code of this currency
     * @since 1.7
     */
    public int getNumericCode() {
        return numericCode;
    }

    /**
     * Returns the 3 digit ISO 4217 numeric code of this currency as a {@code String}.
     * Unlike {@link #getNumericCode()}, which returns the numeric code as {@code int},
     * this method always returns the numeric code as a 3 digit string.
     * e.g. a numeric value of 32 would be returned as "032",
     * and a numeric value of 6 would be returned as "006".
     *
     * @return the 3 digit ISO 4217 numeric code of this currency as a {@code String}
     * @since 9
     */
    public String getNumericCodeAsString() {
        /* numeric code could be returned as a 3 digit string simply by using
           String.format("%03d",numericCode); which uses regex to parse the format,
           "%03d" in this case. Parsing a regex gives an extra performance overhead,
           so String.format() approach is avoided in this scenario.
        */
        if (numericCode < 100) {
            StringBuilder sb = new StringBuilder();
            sb.append('0');
            if (numericCode < 10) {
                sb.append('0');
            }
            return sb.append(numericCode).toString();
        }
        return String.valueOf(numericCode);
    }

    /**
     * Gets the name that is suitable for displaying this currency for
     * the default {@link Locale.Category#DISPLAY DISPLAY} locale.
     * If there is no suitable display name found
     * for the default locale, the ISO 4217 currency code is returned.
     * <p>
     * This is equivalent to calling
     * {@link #getDisplayName(Locale)
     *     getDisplayName(Locale.getDefault(Locale.Category.DISPLAY))}.
     *
     * @return the display name of this currency for the default
     *     {@link Locale.Category#DISPLAY DISPLAY} locale
     * @since 1.7
     */
    public String getDisplayName() {
        return getDisplayName(Locale.getDefault(Locale.Category.DISPLAY));
    }

    /**
     * Gets the name that is suitable for displaying this currency for
     * the specified locale.  If there is no suitable display name found
     * for the specified locale, the ISO 4217 currency code is returned.
     *
     * @param locale the locale for which a display name for this currency is
     * needed
     * @return the display name of this currency for the specified locale
     * @exception NullPointerException if <code>locale</code> is null
     * @since 1.7
     */
    public String getDisplayName(Locale locale) {
        LocaleServiceProviderPool pool =
            LocaleServiceProviderPool.getPool(CurrencyNameProvider.class);
        String result = pool.getLocalizedObject(
                                CurrencyNameGetter.INSTANCE,
                                locale, currencyCode, DISPLAYNAME);
        if (result != null) {
            return result;
        }

        // use currency code as symbol of last resort
        return currencyCode;
    }

    /**
     * Returns the ISO 4217 currency code of this currency.
     *
     * @return the ISO 4217 currency code of this currency
     */
    @Override
    public String toString() {
        return currencyCode;
    }

    /**
     * Resolves instances being deserialized to a single instance per currency.
     */
    private Object readResolve() {
        return getInstance(currencyCode);
    }

    /**
     * Gets the main table entry for the country whose country code consists
     * of char1 and char2.
     */
    private static int getMainTableEntry(char char1, char char2) {
        if (char1 < 'A' || char1 > 'Z' || char2 < 'A' || char2 > 'Z') {
            throw new IllegalArgumentException();
        }
        return mainTable[(char1 - 'A') * A_TO_Z + (char2 - 'A')];
    }

    /**
     * Sets the main table entry for the country whose country code consists
     * of char1 and char2.
     */
    private static void setMainTableEntry(char char1, char char2, int entry) {
        if (char1 < 'A' || char1 > 'Z' || char2 < 'A' || char2 > 'Z') {
            throw new IllegalArgumentException();
        }
        mainTable[(char1 - 'A') * A_TO_Z + (char2 - 'A')] = entry;
    }

    /**
     * Obtains a localized currency names from a CurrencyNameProvider
     * implementation.
     */
    private static class CurrencyNameGetter
        implements LocaleServiceProviderPool.LocalizedObjectGetter<CurrencyNameProvider,
                                                                   String> {
        private static final CurrencyNameGetter INSTANCE = new CurrencyNameGetter();

        @Override
        public String getObject(CurrencyNameProvider currencyNameProvider,
                                Locale locale,
                                String key,
                                Object... params) {
            assert params.length == 1;
            int type = (Integer)params[0];

            switch(type) {
            case SYMBOL:
                return currencyNameProvider.getSymbol(key, locale);
            case DISPLAYNAME:
                return currencyNameProvider.getDisplayName(key, locale);
            default:
                assert false; // shouldn't happen
            }

            return null;
        }
    }

    private static int[] readIntArray(DataInputStream dis, int count) throws IOException {
        int[] ret = new int[count];
        for (int i = 0; i < count; i++) {
            ret[i] = dis.readInt();
        }

        return ret;
    }

    private static List<SpecialCaseEntry> readSpecialCases(DataInputStream dis,
            int count)
            throws IOException {

        List<SpecialCaseEntry> list = new ArrayList<>(count);
        long cutOverTime;
        String oldCurrency;
        String newCurrency;
        int oldCurrencyFraction;
        int newCurrencyFraction;
        int oldCurrencyNumericCode;
        int newCurrencyNumericCode;

        for (int i = 0; i < count; i++) {
            cutOverTime = dis.readLong();
            oldCurrency = dis.readUTF();
            newCurrency = dis.readUTF();
            oldCurrencyFraction = dis.readInt();
            newCurrencyFraction = dis.readInt();
            oldCurrencyNumericCode = dis.readInt();
            newCurrencyNumericCode = dis.readInt();
            SpecialCaseEntry sc = new SpecialCaseEntry(cutOverTime,
                    oldCurrency, newCurrency,
                    oldCurrencyFraction, newCurrencyFraction,
                    oldCurrencyNumericCode, newCurrencyNumericCode);
            list.add(sc);
        }
        return list;
    }

    private static List<OtherCurrencyEntry> readOtherCurrencies(DataInputStream dis,
            int count)
            throws IOException {

        List<OtherCurrencyEntry> list = new ArrayList<>(count);
        String currencyCode;
        int fraction;
        int numericCode;

        for (int i = 0; i < count; i++) {
            currencyCode = dis.readUTF();
            fraction = dis.readInt();
            numericCode = dis.readInt();
            OtherCurrencyEntry oc = new OtherCurrencyEntry(currencyCode,
                    fraction,
                    numericCode);
            list.add(oc);
        }
        return list;
    }

    /**
     * Parse currency data found in the properties file (that
     * java.util.currency.data designates) to a List of CurrencyProperty
     * instances. Also, remove invalid entries and the multiple currency
     * code inconsistencies.
     *
     * @param props properties containing currency data
     * @param pattern regex pattern for the properties entry
     * @return list of parsed property entries
     */
    private static List<CurrencyProperty> getValidCurrencyData(Properties props,
            Pattern pattern) {

        Set<String> keys = props.stringPropertyNames();
        List<CurrencyProperty> propertyEntries = new ArrayList<>();

        // remove all invalid entries and parse all valid currency properties
        // entries to a group of CurrencyProperty, classified by currency code
        Map<String, List<CurrencyProperty>> currencyCodeGroup = keys.stream()
                .map(k -> CurrencyProperty
                .getValidEntry(k.toUpperCase(Locale.ROOT),
                        props.getProperty(k).toUpperCase(Locale.ROOT),
                        pattern)).flatMap(o -> o.stream())
                .collect(Collectors.groupingBy(entry -> entry.currencyCode));

        // check each group for inconsistencies
        currencyCodeGroup.forEach((curCode, list) -> {
            boolean inconsistent = CurrencyProperty
                    .containsInconsistentInstances(list);
            if (inconsistent) {
                list.forEach(prop -> CurrencyProperty.info("The property"
                        + " entry for " + prop.country + " is inconsistent."
                        + " Ignored.", null));
            } else {
                propertyEntries.addAll(list);
            }
        });

        return propertyEntries;
    }

    /**
     * Replaces currency data found in the properties file that
     * java.util.currency.data designates. This method is invoked for
     * each valid currency entry.
     *
     * @param prop CurrencyProperty instance of the valid property entry
     */
    private static void replaceCurrencyData(CurrencyProperty prop) {


        String ctry = prop.country;
        String code = prop.currencyCode;
        int numeric = prop.numericCode;
        int fraction = prop.fraction;
        int entry = numeric << NUMERIC_CODE_SHIFT;

        int index = SpecialCaseEntry.indexOf(code, fraction, numeric);


        // If a new entry changes the numeric code/dfd of an existing
        // currency code, update it in the sc list at the respective
        // index and also change it in the other currencies list and
        // main table (if that currency code is also used as a
        // simple case).

        // If all three components do not match with the new entry,
        // but the currency code exists in the special case list
        // update the sc entry with the new entry
        int scCurrencyCodeIndex = -1;
        if (index == -1) {
            scCurrencyCodeIndex = SpecialCaseEntry.currencyCodeIndex(code);
            if (scCurrencyCodeIndex != -1) {
                //currency code exists in sc list, then update the old entry
                specialCasesList.set(scCurrencyCodeIndex,
                        new SpecialCaseEntry(code, fraction, numeric));

                // also update the entry in other currencies list
                OtherCurrencyEntry oe = OtherCurrencyEntry.findEntry(code);
                if (oe != null) {
                    int oIndex = otherCurrenciesList.indexOf(oe);
                    otherCurrenciesList.set(oIndex, new OtherCurrencyEntry(
                            code, fraction, numeric));
                }
            }
        }

        /* If a country switches from simple case to special case or
         * one special case to other special case which is not present
         * in the sc arrays then insert the new entry in special case arrays.
         * If an entry with given currency code exists, update with the new
         * entry.
         */
        if (index == -1 && (ctry.charAt(0) != code.charAt(0)
                || ctry.charAt(1) != code.charAt(1))) {

            if(scCurrencyCodeIndex == -1) {
                specialCasesList.add(new SpecialCaseEntry(code, fraction,
                        numeric));
                index = specialCasesList.size() - 1;
            } else {
                index = scCurrencyCodeIndex;
            }

            // update the entry in main table if it exists as a simple case
            updateMainTableEntry(code, fraction, numeric);
        }

        if (index == -1) {
            // simple case
            entry |= (fraction << SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT)
                    | (code.charAt(2) - 'A');
        } else {
            // special case
            entry = SPECIAL_CASE_COUNTRY_MASK
                    | (index + SPECIAL_CASE_COUNTRY_INDEX_DELTA);
        }
        setMainTableEntry(ctry.charAt(0), ctry.charAt(1), entry);
    }

    // update the entry in maintable for any simple case found, if a new
    // entry as a special case updates the entry in sc list with
    // existing currency code
    private static void updateMainTableEntry(String code, int fraction,
            int numeric) {
        // checking the existence of currency code in mainTable
        int tableEntry = getMainTableEntry(code.charAt(0), code.charAt(1));
        int entry = numeric << NUMERIC_CODE_SHIFT;
        if ((tableEntry & COUNTRY_TYPE_MASK) == SIMPLE_CASE_COUNTRY_MASK
                && tableEntry != INVALID_COUNTRY_ENTRY
                && code.charAt(2) - 'A' == (tableEntry
                & SIMPLE_CASE_COUNTRY_FINAL_CHAR_MASK)) {

            int numericCode = (tableEntry & NUMERIC_CODE_MASK)
                    >> NUMERIC_CODE_SHIFT;
            int defaultFractionDigits = (tableEntry
                    & SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_MASK)
                    >> SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT;
            if (numeric != numericCode || fraction != defaultFractionDigits) {
                // update the entry in main table
                entry |= (fraction << SIMPLE_CASE_COUNTRY_DEFAULT_DIGITS_SHIFT)
                        | (code.charAt(2) - 'A');
                setMainTableEntry(code.charAt(0), code.charAt(1), entry);
            }
        }
    }

    /* Used to represent a special case currency entry
     * - cutOverTime: cut-over time in millis as returned by
     *   System.currentTimeMillis for special case countries that are changing
     *   currencies; Long.MAX_VALUE for countries that are not changing currencies
     * - oldCurrency: old currencies for special case countries
     * - newCurrency: new currencies for special case countries that are
     *   changing currencies; null for others
     * - oldCurrencyFraction: default fraction digits for old currencies
     * - newCurrencyFraction: default fraction digits for new currencies, 0 for
     *   countries that are not changing currencies
     * - oldCurrencyNumericCode: numeric code for old currencies
     * - newCurrencyNumericCode: numeric code for new currencies, 0 for countries
     *   that are not changing currencies
    */
    private static class SpecialCaseEntry {

        final private long cutOverTime;
        final private String oldCurrency;
        final private String newCurrency;
        final private int oldCurrencyFraction;
        final private int newCurrencyFraction;
        final private int oldCurrencyNumericCode;
        final private int newCurrencyNumericCode;

        private SpecialCaseEntry(long cutOverTime, String oldCurrency, String newCurrency,
                int oldCurrencyFraction, int newCurrencyFraction,
                int oldCurrencyNumericCode, int newCurrencyNumericCode) {
            this.cutOverTime = cutOverTime;
            this.oldCurrency = oldCurrency;
            this.newCurrency = newCurrency;
            this.oldCurrencyFraction = oldCurrencyFraction;
            this.newCurrencyFraction = newCurrencyFraction;
            this.oldCurrencyNumericCode = oldCurrencyNumericCode;
            this.newCurrencyNumericCode = newCurrencyNumericCode;
        }

        private SpecialCaseEntry(String currencyCode, int fraction,
                int numericCode) {
            this(Long.MAX_VALUE, currencyCode, "", fraction, 0, numericCode, 0);
        }

        //get the index of the special case entry
        private static int indexOf(String code, int fraction, int numeric) {
            int size = specialCasesList.size();
            for (int index = 0; index < size; index++) {
                SpecialCaseEntry scEntry = specialCasesList.get(index);
                if (scEntry.oldCurrency.equals(code)
                        && scEntry.oldCurrencyFraction == fraction
                        && scEntry.oldCurrencyNumericCode == numeric
                        && scEntry.cutOverTime == Long.MAX_VALUE) {
                    return index;
                }
            }
            return -1;
        }

        // get the fraction and numericCode of the sc currencycode
        private static int[] findEntry(String code) {
            int[] fractionAndNumericCode = null;
            int size = specialCasesList.size();
            for (int index = 0; index < size; index++) {
                SpecialCaseEntry scEntry = specialCasesList.get(index);
                if (scEntry.oldCurrency.equals(code) && (scEntry.cutOverTime == Long.MAX_VALUE
                        || System.currentTimeMillis() < scEntry.cutOverTime)) {
                    //consider only when there is no new currency or cutover time is not passed
                    fractionAndNumericCode = new int[2];
                    fractionAndNumericCode[0] = scEntry.oldCurrencyFraction;
                    fractionAndNumericCode[1] = scEntry.oldCurrencyNumericCode;
                    break;
                } else if (scEntry.newCurrency.equals(code)
                        && System.currentTimeMillis() >= scEntry.cutOverTime) {
                    //consider only if the cutover time is passed
                    fractionAndNumericCode = new int[2];
                    fractionAndNumericCode[0] = scEntry.newCurrencyFraction;
                    fractionAndNumericCode[1] = scEntry.newCurrencyNumericCode;
                    break;
                }
            }
            return fractionAndNumericCode;
        }

        // get the index based on currency code
        private static int currencyCodeIndex(String code) {
            int size = specialCasesList.size();
            for (int index = 0; index < size; index++) {
                SpecialCaseEntry scEntry = specialCasesList.get(index);
                if (scEntry.oldCurrency.equals(code) && (scEntry.cutOverTime == Long.MAX_VALUE
                        || System.currentTimeMillis() < scEntry.cutOverTime)) {
                    //consider only when there is no new currency or cutover time is not passed
                    return index;
                } else if (scEntry.newCurrency.equals(code)
                        && System.currentTimeMillis() >= scEntry.cutOverTime) {
                    //consider only if the cutover time is passed
                    return index;
                }
            }
            return -1;
        }


        // convert the special case entry to sc arrays index
        private static int toIndex(int tableEntry) {
            return (tableEntry & SPECIAL_CASE_COUNTRY_INDEX_MASK) - SPECIAL_CASE_COUNTRY_INDEX_DELTA;
        }

    }

    /* Used to represent Other currencies
     * - currencyCode: currency codes that are not the main currency
     *   of a simple country
     * - otherCurrenciesDFD: decimal format digits for other currencies
     * - otherCurrenciesNumericCode: numeric code for other currencies
     */
    private static class OtherCurrencyEntry {

        final private String currencyCode;
        final private int fraction;
        final private int numericCode;

        private OtherCurrencyEntry(String currencyCode, int fraction,
                int numericCode) {
            this.currencyCode = currencyCode;
            this.fraction = fraction;
            this.numericCode = numericCode;
        }

        //get the instance of the other currency code
        private static OtherCurrencyEntry findEntry(String code) {
            int size = otherCurrenciesList.size();
            for (int index = 0; index < size; index++) {
                OtherCurrencyEntry ocEntry = otherCurrenciesList.get(index);
                if (ocEntry.currencyCode.equalsIgnoreCase(code)) {
                    return ocEntry;
                }
            }
            return null;
        }

    }


    /*
     * Used to represent an entry of the properties file that
     * java.util.currency.data designates
     *
     * - country: country representing the currency entry
     * - currencyCode: currency code
     * - fraction: default fraction digit
     * - numericCode: numeric code
     * - date: cutover date
     */
    private static class CurrencyProperty {
        final private String country;
        final private String currencyCode;
        final private int fraction;
        final private int numericCode;
        final private String date;

        private CurrencyProperty(String country, String currencyCode,
                int fraction, int numericCode, String date) {
            this.country = country;
            this.currencyCode = currencyCode;
            this.fraction = fraction;
            this.numericCode = numericCode;
            this.date = date;
        }

        /**
         * Check the valid currency data and create/return an Optional instance
         * of CurrencyProperty
         *
         * @param ctry    country representing the currency data
         * @param curData currency data of the given {@code ctry}
         * @param pattern regex pattern for the properties entry
         * @return Optional containing CurrencyProperty instance, If valid;
         *         empty otherwise
         */
        private static Optional<CurrencyProperty> getValidEntry(String ctry,
                String curData,
                Pattern pattern) {

            CurrencyProperty prop = null;

            if (ctry.length() != 2) {
                // Invalid country code. Ignore the entry.
            } else {

                prop = parseProperty(ctry, curData, pattern);
                // if the property entry failed any of the below checked
                // criteria it is ignored
                if (prop == null
                        || (prop.date == null && curData.chars()
                                .map(c -> c == ',' ? 1 : 0).sum() >= 3)) {
                    // format is not recognized.  ignore the data if date
                    // string is null and we've 4 values, bad date value
                    prop = null;
                } else if (prop.fraction
                        > SIMPLE_CASE_COUNTRY_MAX_DEFAULT_DIGITS) {
                    prop = null;
                } else {
                    try {
                        if (prop.date != null
                                && !isPastCutoverDate(prop.date)) {
                            prop = null;
                        }
                    } catch (ParseException ex) {
                        prop = null;
                    }
                }
            }

            if (prop == null) {
                info("The property entry for " + ctry + " is invalid."
                        + " Ignored.", null);
            }

            return Optional.ofNullable(prop);
        }

        /*
         * Parse properties entry and return CurrencyProperty instance
         */
        private static CurrencyProperty parseProperty(String ctry,
                String curData, Pattern pattern) {
            Matcher m = pattern.matcher(curData);
            if (!m.find()) {
                return null;
            } else {
                return new CurrencyProperty(ctry, m.group(1),
                        Integer.parseInt(m.group(3)),
                        Integer.parseInt(m.group(2)), m.group(4));
            }
        }

        /**
         * Checks if the given list contains multiple inconsistent currency instances
         */
        private static boolean containsInconsistentInstances(
                List<CurrencyProperty> list) {
            int numCode = list.get(0).numericCode;
            int fractionDigit = list.get(0).fraction;
            return list.stream().anyMatch(prop -> prop.numericCode != numCode
                    || prop.fraction != fractionDigit);
        }

        private static boolean isPastCutoverDate(String s)
                throws ParseException {
            SimpleDateFormat format = new SimpleDateFormat(
                    "yyyy-MM-dd'T'HH:mm:ss", Locale.ROOT);
            format.setTimeZone(TimeZone.getTimeZone("UTC"));
            format.setLenient(false);
            long time = format.parse(s.trim()).getTime();
            return System.currentTimeMillis() > time;

        }

        private static void info(String message, Throwable t) {
            PlatformLogger logger = PlatformLogger
                    .getLogger("java.util.Currency");
            if (logger.isLoggable(PlatformLogger.Level.INFO)) {
                if (t != null) {
                    logger.info(message, t);
                } else {
                    logger.info(message);
                }
            }
        }

    }

}