LocaleUtils.java
/*
* 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
*
* https://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.
*/
package org.apache.commons.lang3;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.function.Predicate;
import java.util.stream.Collectors;
/**
* Operations to assist when working with a {@link Locale}.
*
* <p>
* This class tries to handle {@code null} input gracefully. An exception will not be thrown for a {@code null} input. Each method documents its behavior in
* more detail.
* </p>
*
* @see Locale
* @since 2.2
*/
public class LocaleUtils {
/**
* Avoids synchronization, initializes on demand.
*/
private static final class SyncAvoid {
/** Private unmodifiable and sorted list of available locales. */
private static final List<Locale> AVAILABLE_LOCALE_ULIST;
/** Private unmodifiable set of available locales. */
private static final Set<Locale> AVAILABLE_LOCALE_USET;
static {
AVAILABLE_LOCALE_ULIST = Collections
.unmodifiableList(Arrays.asList(ArraySorter.sort(Locale.getAvailableLocales(), Comparator.comparing(Locale::toString))));
AVAILABLE_LOCALE_USET = Collections.unmodifiableSet(new LinkedHashSet<>(AVAILABLE_LOCALE_ULIST));
}
}
/**
* The underscore character {@code '}{@value}{@code '}.
*/
private static final char UNDERSCORE = '_';
/**
* The undetermined language {@value}.
* <p>
* If a language is empty, or not <em>well-formed</am> (for example "a" or "e2"), {@link Locale#toLanguageTag()} will return {@code "und"} (Undetermined).
* </p>
*
* @see Locale#toLanguageTag()
*/
private static final String UNDETERMINED = "und";
/**
* The dash character {@code '}{@value}{@code '}.
*/
private static final char DASH = '-';
/**
* Concurrent map of language locales by country.
*/
private static final ConcurrentMap<String, List<Locale>> cLanguagesByCountry = new ConcurrentHashMap<>();
/**
* Concurrent map of country locales by language.
*/
private static final ConcurrentMap<String, List<Locale>> cCountriesByLanguage = new ConcurrentHashMap<>();
/**
* Obtains an unmodifiable and sorted list of installed locales.
*
* <p>
* This method is a wrapper around {@link Locale#getAvailableLocales()}. It is more efficient, as the JDK method must create a new array each time it is
* called.
* </p>
*
* @return the unmodifiable and sorted list of available locales.
*/
public static List<Locale> availableLocaleList() {
return SyncAvoid.AVAILABLE_LOCALE_ULIST;
}
private static List<Locale> availableLocaleList(final Predicate<Locale> predicate) {
return availableLocaleList().stream().filter(predicate).collect(Collectors.toList());
}
/**
* Obtains an unmodifiable set of installed locales.
*
* <p>
* This method is a wrapper around {@link Locale#getAvailableLocales()}. It is more efficient, as the JDK method must create a new array each time it is
* called.
* </p>
*
* @return the unmodifiable set of available locales.
*/
public static Set<Locale> availableLocaleSet() {
return SyncAvoid.AVAILABLE_LOCALE_USET;
}
/**
* Obtains the list of countries supported for a given language.
*
* <p>
* This method takes a language code and searches to find the countries available for that language. Variant locales are removed.
* </p>
*
* @param languageCode the 2 letter language code, null returns empty.
* @return an unmodifiable List of Locale objects, not null.
*/
public static List<Locale> countriesByLanguage(final String languageCode) {
if (languageCode == null) {
return Collections.emptyList();
}
return cCountriesByLanguage.computeIfAbsent(languageCode, lc -> Collections
.unmodifiableList(availableLocaleList(locale -> languageCode.equals(locale.getLanguage()) && !hasCountry(locale) && hasVariant(locale))));
}
/**
* Tests whether the given Locale defines a variant.
*
* @param locale The Locale to test.
* @return whether the given Locale defines a variant.
*/
private static boolean hasCountry(final Locale locale) {
return locale.getCountry().isEmpty();
}
/**
* Tests whether the given Locale defines a country.
*
* @param locale The Locale to test.
* @return whether the given Locale defines a country.
*/
private static boolean hasVariant(final Locale locale) {
return locale.getVariant().isEmpty();
}
/**
* Tests whether the given string is the length of an <a href="https://www.iso.org/iso-3166-country-codes.html">ISO 3166</a> alpha-2 country code.
*
* @param str The string to test.
* @return whether the given string is the length of an <a href="https://www.iso.org/iso-3166-country-codes.html">ISO 3166</a> alpha-2 country code.
*/
private static boolean isAlpha2Len(final String str) {
return str.length() == 2;
}
/**
* Tests whether the given string is the length of an <a href="https://www.iso.org/iso-3166-country-codes.html">ISO 3166</a> alpha-3 country code.
*
* @param str The string to test.
* @return whether the given string is the length of an <a href="https://www.iso.org/iso-3166-country-codes.html">ISO 3166</a> alpha-3 country code.
*/
private static boolean isAlpha3Len(final String str) {
return str.length() == 3;
}
/**
* Checks if the locale specified is in the set of available locales.
*
* @param locale the Locale object to check if it is available.
* @return true if the locale is a known locale.
*/
public static boolean isAvailableLocale(final Locale locale) {
return availableLocaleSet().contains(locale);
}
/**
* Tests whether the given String is a <a href="https://www.iso.org/iso-3166-country-codes.html">ISO 3166</a> alpha-2 country code.
*
* @param str the String to check.
* @return true, is the given String is a <a href="https://www.iso.org/iso-3166-country-codes.html">ISO 3166</a> compliant country code.
*/
private static boolean isISO3166CountryCode(final String str) {
return StringUtils.isAllUpperCase(str) && isAlpha2Len(str);
}
/**
* Tests whether the given String is a <a href="https://www.iso.org/iso-639-language-code">ISO 639</a> compliant language code.
*
* @param str the String to check.
* @return true, if the given String is a <a href="https://www.iso.org/iso-639-language-code">ISO 639</a> compliant language code.
*/
private static boolean isISO639LanguageCode(final String str) {
return StringUtils.isAllLowerCase(str) && (isAlpha2Len(str) || isAlpha3Len(str));
}
/**
* Tests whether a Locale's language is undetermined.
* <p>
* A Locale's language tag is undetermined if it's value is {@code "und"}. If a language is empty, or not well-formed (for example, "a" or "e2"), it will be
* equal to {@code "und"}.
* </p>
*
* @param locale the locale to test.
* @return whether a Locale's language is undetermined.
* @see Locale#toLanguageTag()
* @since 3.14.0
*/
public static boolean isLanguageUndetermined(final Locale locale) {
return locale == null || UNDETERMINED.equals(locale.toLanguageTag());
}
/**
* TestsNo whether the given String is a UN M.49 numeric area code.
*
* @param str the String to check.
* @return true, is the given String is a UN M.49 numeric area code.
*/
private static boolean isNumericAreaCode(final String str) {
return StringUtils.isNumeric(str) && isAlpha3Len(str);
}
/**
* Obtains the list of languages supported for a given country.
*
* <p>
* This method takes a country code and searches to find the languages available for that country. Variant locales are removed.
* </p>
*
* @param countryCode the 2-letter country code, null returns empty.
* @return an unmodifiable List of Locale objects, not null.
*/
public static List<Locale> languagesByCountry(final String countryCode) {
if (countryCode == null) {
return Collections.emptyList();
}
return cLanguagesByCountry.computeIfAbsent(countryCode,
k -> Collections.unmodifiableList(availableLocaleList(locale -> countryCode.equals(locale.getCountry()) && hasVariant(locale))));
}
/**
* Obtains the list of locales to search through when performing a locale search.
*
* <pre>
* localeLookupList(Locale("fr", "CA", "xxx"))
* = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr")]
* </pre>
*
* @param locale the locale to start from.
* @return the unmodifiable list of Locale objects, 0 being locale, not null.
*/
public static List<Locale> localeLookupList(final Locale locale) {
return localeLookupList(locale, locale);
}
/**
* Obtains the list of locales to search through when performing a locale search.
*
* <pre>
* localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))
* = [Locale("fr", "CA", "xxx"), Locale("fr", "CA"), Locale("fr"), Locale("en"]
* </pre>
*
* <p>
* The result list begins with the most specific locale, then the next more general and so on, finishing with the default locale. The list will never
* contain the same locale twice.
* </p>
*
* @param locale the locale to start from, null returns empty list.
* @param defaultLocale the default locale to use if no other is found.
* @return the unmodifiable list of Locale objects, 0 being locale, not null.
*/
public static List<Locale> localeLookupList(final Locale locale, final Locale defaultLocale) {
final List<Locale> list = new ArrayList<>(4);
if (locale != null) {
list.add(locale);
if (!hasVariant(locale)) {
list.add(new Locale(locale.getLanguage(), locale.getCountry()));
}
if (!hasCountry(locale)) {
list.add(new Locale(locale.getLanguage(), StringUtils.EMPTY));
}
if (!list.contains(defaultLocale)) {
list.add(defaultLocale);
}
}
return Collections.unmodifiableList(list);
}
/**
* Creates new {@linkplain Locale} for the given country.
*
* @param country An ISO 3166 alpha-2 country code or a UN M.49 numeric-3 area code. See the {@linkplain Locale} class description about valid country
* values.
* @throws NullPointerException thrown if either argument is null.
* @return a new new Locale for the given country.
* @see Locale#Locale(String, String)
*/
static Locale ofCountry(final String country) {
return new Locale(StringUtils.EMPTY, country);
}
/**
* Tries to parse a Locale from the given String.
* <p>
* See {@link Locale} for the format.
* </p>
*
* @param str the String to parse as a Locale.
* @return a Locale parsed from the given String.
* @throws IllegalArgumentException if the given String cannot be parsed.
* @see Locale
*/
private static Locale parseLocale(final String str) {
if (isISO639LanguageCode(str)) {
return new Locale(str);
}
final int limit = 3;
final char separator = str.indexOf(UNDERSCORE) != -1 ? UNDERSCORE : DASH;
final String[] segments = str.split(String.valueOf(separator), 3);
final String language = segments[0];
if (segments.length == 2) {
final String country = segments[1];
if (isISO639LanguageCode(language) && isISO3166CountryCode(country) || isNumericAreaCode(country)) {
return new Locale(language, country);
}
} else if (segments.length == limit) {
final String country = segments[1];
final String variant = segments[2];
if (isISO639LanguageCode(language) && (country.isEmpty() || isISO3166CountryCode(country) || isNumericAreaCode(country)) && !variant.isEmpty()) {
return new Locale(language, country, variant);
}
}
if (ArrayUtils.contains(Locale.getISOCountries(), str)) {
return new Locale(StringUtils.EMPTY, str);
}
throw new IllegalArgumentException("Invalid locale format: " + str);
}
/**
* Returns the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
*
* @param locale a locale or {@code null}.
* @return the given locale if non-{@code null}, otherwise {@link Locale#getDefault()}.
* @since 3.12.0
*/
public static Locale toLocale(final Locale locale) {
return locale != null ? locale : Locale.getDefault();
}
/**
* Converts a String to a Locale.
*
* <p>
* This method takes the string format of a locale and creates the locale object from it.
* </p>
*
* <pre>
* LocaleUtils.toLocale("") = new Locale("", "")
* LocaleUtils.toLocale("en") = new Locale("en", "")
* LocaleUtils.toLocale("en_GB") = new Locale("en", "GB")
* LocaleUtils.toLocale("en-GB") = new Locale("en", "GB")
* LocaleUtils.toLocale("en_001") = new Locale("en", "001")
* LocaleUtils.toLocale("en_GB_xxx") = new Locale("en", "GB", "xxx") (#)
* LocaleUtils.toLocale("US") = new Locale("", "US") // Because "US" is Locale.getISOCountries()
* </pre>
*
* <p>
* (#) The behavior of the JDK variant constructor changed between JDK1.3 and JDK1.4. In JDK1.3, the constructor upper cases the variant, in JDK1.4, it
* doesn't. Thus, the result from getVariant() may vary depending on your JDK.
* </p>
*
* <p>
* This method validates the input strictly. The language code must be lowercase. The country code must be uppercase. The separator must be an underscore or
* a dash. The length must be correct.
* </p>
*
* @param str the locale String to convert, null returns null.
* @return a Locale, null if null input.
* @throws IllegalArgumentException if the string is an invalid format.
* @see Locale#forLanguageTag(String)
* @see Locale#getISOCountries()
*/
public static Locale toLocale(final String str) {
if (str == null) {
// TODO Should this return the default locale?
return null;
}
if (str.isEmpty()) { // LANG-941 - JDK 8 introduced an empty locale where all fields are blank
return new Locale(StringUtils.EMPTY, StringUtils.EMPTY);
}
if (str.contains("#")) { // LANG-879 - Cannot handle Java 7 script & extensions
throw new IllegalArgumentException("Invalid locale format: " + str);
}
final int len = str.length();
if (len < 2) {
throw new IllegalArgumentException("Invalid locale format: " + str);
}
final char ch0 = str.charAt(0);
if (ch0 == UNDERSCORE || ch0 == DASH) {
if (len < 3) {
throw new IllegalArgumentException("Invalid locale format: " + str);
}
final char ch1 = str.charAt(1);
final char ch2 = str.charAt(2);
if (!Character.isUpperCase(ch1) || !Character.isUpperCase(ch2)) {
throw new IllegalArgumentException("Invalid locale format: " + str);
}
if (len == 3) {
return new Locale(StringUtils.EMPTY, str.substring(1, 3));
}
if (len < 5) {
throw new IllegalArgumentException("Invalid locale format: " + str);
}
if (str.charAt(3) != ch0) {
throw new IllegalArgumentException("Invalid locale format: " + str);
}
return new Locale(StringUtils.EMPTY, str.substring(1, 3), str.substring(4));
}
return parseLocale(str);
}
/**
* {@link LocaleUtils} instances should NOT be constructed in standard programming. Instead, the class should be used as
* {@code LocaleUtils.toLocale("en_GB");}.
*
* <p>
* This constructor is public to permit tools that require a JavaBean instance to operate.
* </p>
*
* @deprecated TODO Make private in 4.0.
*/
@Deprecated
public LocaleUtils() {
// empty
}
}