currency.java

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                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;
                } else {
                    // Check for '-' separately so we don't get false hits in the table.
                    if (currencyCode.charAt(2) == '-') {
                        throw new IllegalArgumentException();
                    }
                    int index = otherCurrencies.indexOf(currencyCode);
                    if (index == -1) {
                        throw new IllegalArgumentException();
                    }
                    defaultFractionDigits = otherCurrenciesDFD[index / 4];
                }
            }
        
            instance = new Currency(currencyCode, defaultFractionDigits);
            instances.put(currencyCode, instance);
            return instance;
        }
    }
    
    /**
     * 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>
     * 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 null
     * @exception NullPointerException if <code>locale</code> or its country
     * code is null
     * @exception IllegalArgumentException if the country of the given locale
     * is not a supported ISO 3166 country code.
     */
    public static Currency getInstance(Locale locale) {
        String country = locale.getCountry();
        if (country == null) {
            throw new NullPointerException();
        }

        if (country.length() != 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;
            StringBuffer sb = new StringBuffer(country);
            sb.append(finalChar);
            return getInstance(sb.toString(), defaultFractionDigits);
        } else {
            // special cases
            if (tableEntry == INVALID_COUNTRY_ENTRY) {
                throw new IllegalArgumentException();
            }
            if (tableEntry == COUNTRY_WITHOUT_CURRENCY_ENTRY) {
                return null;
            } else {
                int index = (tableEntry & SPECIAL_CASE_COUNTRY_INDEX_MASK) - SPECIAL_CASE_COUNTRY_INDEX_DELTA;
                if (scCutOverTimes[index] == Long.MAX_VALUE || System.currentTimeMillis() < scCutOverTimes[index]) {
                    return getInstance(scOldCurrencies[index], scOldCurrenciesDFD[index]);
                } else {
                    return getInstance(scNewCurrencies[index], scNewCurrenciesDFD[index]);
                }
            }
        }
    }
    
    /**
     * 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 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.
     *
     * @return the symbol of this currency for the default locale
     */
    public String getSymbol() {
        return getSymbol(Locale.getDefault());
    }
    
    /**
     * 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.
     *
     * @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) {
        ResourceBundle bundle;
        try {
            bundle = LocaleData.getLocaleElements(locale);
        } catch (MissingResourceException e) {
            // use currency code as symbol of last resort
            return currencyCode;
        }
        String[][] symbols =
                (String[][]) bundle.getObject("CurrencySymbols");
        if (symbols != null) {
            for (int i = 0; i < symbols.length; i++) {
                if (symbols[i][0].equals(currencyCode)) {
                    return symbols[i][1];
                }
            }
        }
        // use currency code as symbol of last resort
        return currencyCode;
    }
    
    /**
     * Gets the default number of fraction digits used with this 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 currency code of this currency.
     *
     * @return the ISO 4217 currency code of this currency
     */
    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.charAt((char1 - 'A') * A_TO_Z + (char2 - 'A'));
    }
}