356 lines
11 KiB
Java
356 lines
11 KiB
Java
/* Currency.java -- Representation of a currency
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Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.util;
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import java.io.ObjectStreamException;
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import java.io.Serializable;
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import java.text.NumberFormat;
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/**
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* Representation of a currency for a particular locale. Each currency
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* is identified by its ISO 4217 code, and only one instance of this
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* class exists per currency. As a result, instances are created
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* via the <code>getInstance()</code> methods rather than by using
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* a constructor.
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*
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* @see java.util.Locale
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* @author Guilhem Lavaux (guilhem.lavaux@free.fr)
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* @author Dalibor Topic (robilad@kaffe.org)
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* @author Bryce McKinlay (mckinlay@redhat.com)
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* @author Andrew John Hughes (gnu_andrew@member.fsf.org)
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* @since 1.4
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*/
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public final class Currency
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implements Serializable
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{
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/**
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* For compatability with Sun's JDK
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*/
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static final long serialVersionUID = -158308464356906721L;
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/**
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* The locale associated with this currency.
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*
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* @see #Currency(java.util.Locale)
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* @see #getInstance(java.util.Locale)
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* @see #getSymbol(java.util.Locale)
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* @serial ignored.
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*/
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private transient Locale locale;
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/**
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* The resource bundle which maps the currency to
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* a ISO 4217 currency code.
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*
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* @see #getCurrencyCode()
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* @serial ignored.
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*/
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private transient ResourceBundle res;
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/**
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* The ISO 4217 currency code associated with this
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* particular instance.
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*
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* @see #getCurrencyCode()
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* @serial the ISO 4217 currency code
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*/
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private String currencyCode;
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/**
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* A cache of <code>Currency</code> instances to
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* ensure the singleton nature of this class. The key
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* is the locale of the currency.
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*
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* @see #getInstance(java.util.Locale)
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* @see #readResolve()
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* @serial ignored.
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*/
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private static transient Map cache;
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/**
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* Instantiates the cache.
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*/
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static
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{
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cache = new HashMap();
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}
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/**
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* Default constructor for deserialization
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*/
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private Currency ()
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{
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}
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/**
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* Constructor to create a <code>Currency</code> object
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* for a particular <code>Locale</code>.
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* All components of the given locale, other than the
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* country code, are ignored. The results of calling this
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* method may vary over time, as the currency associated with
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* a particular country changes. For countries without
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* a given currency (e.g. Antarctica), the result is null.
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*
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* @param loc the locale for the new currency.
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*/
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private Currency (Locale loc)
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{
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this.locale = loc;
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this.res = ResourceBundle.getBundle ("gnu.java.locale.LocaleInformation",
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locale, ClassLoader.getSystemClassLoader());
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/* Retrieve the ISO4217 currency code */
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try
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{
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currencyCode = res.getString ("intlCurrencySymbol");
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}
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catch (Exception _)
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{
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currencyCode = null;
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}
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}
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/**
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* Returns the ISO4217 currency code of this currency.
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*
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* @return a <code>String</code> containing currency code.
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*/
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public String getCurrencyCode ()
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{
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return currencyCode;
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}
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/**
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* Returns the number of digits which occur after the decimal point
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* for this particular currency. For example, currencies such
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* as the U.S. dollar, the Euro and the Great British pound have two
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* digits following the decimal point to indicate the value which exists
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* in the associated lower-valued coinage (cents in the case of the first
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* two, pennies in the latter). Some currencies such as the Japanese
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* Yen have no digits after the decimal point. In the case of pseudo
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* currencies, such as IMF Special Drawing Rights, -1 is returned.
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*
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* @return the number of digits after the decimal separator for this currency.
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*/
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public int getDefaultFractionDigits ()
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{
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NumberFormat currency = NumberFormat.getCurrencyInstance (locale);
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return currency.getMaximumFractionDigits();
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}
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/**
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* Builds a new currency instance for this locale.
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* All components of the given locale, other than the
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* country code, are ignored. The results of calling this
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* method may vary over time, as the currency associated with
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* a particular country changes. For countries without
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* a given currency (e.g. Antarctica), the result is null.
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*
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* @param locale a <code>Locale</code> instance.
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* @return a new <code>Currency</code> instance.
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* @throws NullPointerException if the locale or its
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* country code is null.
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* @throws IllegalArgumentException if the country of
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* the given locale is not a supported ISO3166 code.
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*/
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public static Currency getInstance (Locale locale)
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{
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/**
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* The new instance must be the only available instance
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* for the currency it supports. We ensure this happens,
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* while maintaining a suitable performance level, by
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* creating the appropriate object on the first call to
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* this method, and returning the cached instance on
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* later calls.
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*/
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Currency newCurrency;
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/* Attempt to get the currency from the cache */
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newCurrency = (Currency) cache.get(locale);
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if (newCurrency == null)
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{
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/* Create the currency for this locale */
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newCurrency = new Currency (locale);
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/* Cache it */
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cache.put(locale, newCurrency);
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}
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/* Return the instance */
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return newCurrency;
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}
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/**
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* Builds the currency corresponding to the specified currency code.
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*
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* @param currencyCode a string representing a currency code.
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* @return a new <code>Currency</code> instance.
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* @throws NullPointerException if currencyCode is null.
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* @throws IllegalArgumentException if the supplied currency code
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* is not a supported ISO 4217 code.
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*/
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public static Currency getInstance (String currencyCode)
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{
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Locale[] allLocales = Locale.getAvailableLocales ();
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for (int i = 0;i < allLocales.length; i++)
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{
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Currency testCurrency = getInstance (allLocales[i]);
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if (testCurrency.getCurrencyCode() != null &&
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testCurrency.getCurrencyCode().equals(currencyCode))
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return testCurrency;
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}
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/*
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* If we get this far, the code is not supported by any of
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* our locales.
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*/
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throw new IllegalArgumentException("The currency code, " + currencyCode +
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", is not supported.");
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}
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/**
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* This method returns the symbol which precedes or follows a
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* value in this particular currency. In cases where there is no
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* such symbol for the currency, the ISO 4217 currency
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* code is returned.
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*
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* @return the currency symbol, or the ISO 4217 currency code if
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* one doesn't exist.
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*/
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public String getSymbol()
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{
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try
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{
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/* What does this return if there is no mapping? */
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return res.getString ("currencySymbol");
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}
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catch (Exception _)
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{
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return null;
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}
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}
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/**
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* <p>
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* This method returns the symbol which precedes or follows a
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* value in this particular currency. The returned value is
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* the symbol used to denote the currency in the specified locale.
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* </p>
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* <p>
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* For example, a supplied locale may specify a different symbol
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* for the currency, due to conflicts with its own currency.
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* This would be the case with the American currency, the dollar.
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* Locales that also use a dollar-based currency (e.g. Canada, Australia)
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* need to differentiate the American dollar using 'US$' rather than '$'.
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* So, supplying one of these locales to <code>getSymbol()</code> would
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* return this value, rather than the standard '$'.
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* </p>
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* <p>
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* In cases where there is no such symbol for a particular currency,
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* the ISO 4217 currency code is returned.
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* </p>
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*
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* @param locale the locale to express the symbol in.
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* @return the currency symbol, or the ISO 4217 currency code if
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* one doesn't exist.
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* @throws NullPointerException if the locale is null.
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*/
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public String getSymbol(Locale locale)
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{
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// TODO. The behaviour is unclear if locale != this.locale.
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// First we need to implement fully LocaleInformation*.java
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/*
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* FIXME: My reading of how this method works has this implementation
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* as wrong. It should return a value relating to how the specified
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* locale handles the symbol for this currency. This implementation
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* seems to just do a variation of getInstance(locale).
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*/
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try
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{
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ResourceBundle localeResource =
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ResourceBundle.getBundle ("gnu.java.locale.LocaleInformation",
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locale, Currency.class.getClassLoader());
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if (localeResource.equals(res))
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return localeResource.getString ("currencySymbol");
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else
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return localeResource.getString ("intlCurrencySymbol");
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}
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catch (Exception e1)
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{
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try
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{
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return res.getString ("intlCurrencySymbol");
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}
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catch (Exception e2)
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{
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return null;
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}
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}
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}
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/**
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* Returns the international ISO4217 currency code of this currency.
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*
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* @return a <code>String</code> containing the ISO4217 currency code.
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*/
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public String toString()
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{
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return getCurrencyCode();
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}
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/**
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* Resolves the deserialized object to the singleton instance for its
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* particular currency. The currency code of the deserialized instance
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* is used to return the correct instance.
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*
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* @return the singleton instance for the currency specified by the
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* currency code of the deserialized object. This replaces
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* the deserialized object as the returned object from
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* deserialization.
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* @throws ObjectStreamException if a problem occurs with deserializing
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* the object.
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*/
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private Object readResolve()
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throws ObjectStreamException
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{
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return getInstance(currencyCode);
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}
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}
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