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	/*
	* Copyright (c) 2000, 2021, 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
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.nio.charset;

	import jdk.internal.misc.VM;
	import sun.nio.cs.ThreadLocalCoders;
	import sun.security.action.GetPropertyAction;

	import java.nio.ByteBuffer;
	import java.nio.CharBuffer;
	import java.nio.charset.spi.CharsetProvider;
	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import java.util.Arrays;
	import java.util.Collections;
	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.Locale;
	import java.util.Map;
	import java.util.NoSuchElementException;
	import java.util.Objects;
	import java.util.ServiceConfigurationError;
	import java.util.ServiceLoader;
	import java.util.Set;
	import java.util.SortedMap;
	import java.util.TreeMap;


	/**
	* A named mapping between sequences of sixteen-bit Unicode <a
	* href="../../lang/Character.html#unicode">code units</a> and sequences of
	* bytes. This class defines methods for creating decoders and encoders and
	* for retrieving the various names associated with a charset. Instances of
	* this class are immutable.
	*
	* <p> This class also defines static methods for testing whether a particular
	* charset is supported, for locating charset instances by name, and for
	* constructing a map that contains every charset for which support is
	* available in the current Java virtual machine. Support for new charsets can
	* be added via the service-provider interface defined in the {@link
	* java.nio.charset.spi.CharsetProvider} class.
	*
	* <p> All of the methods defined in this class are safe for use by multiple
	* concurrent threads.
	*
	*
	* <h2><a id="names">Charset names</a></h2>
	*
	* <p> Charsets are named by strings composed of the following characters:
	*
	* <ul>
	*
	* <li> The uppercase letters {@code 'A'} through {@code 'Z'}
	* (<code>'\u0041'</code> through <code>'\u005a'</code>),
	*
	* <li> The lowercase letters {@code 'a'} through {@code 'z'}
	* (<code>'\u0061'</code> through <code>'\u007a'</code>),
	*
	* <li> The digits {@code '0'} through {@code '9'}
	* (<code>'\u0030'</code> through <code>'\u0039'</code>),
	*
	* <li> The dash character {@code '-'}
	* (<code>'\u002d'</code>, <small>HYPHEN-MINUS</small>),
	*
	* <li> The plus character {@code '+'}
	* (<code>'\u002b'</code>, <small>PLUS SIGN</small>),
	*
	* <li> The period character {@code '.'}
	* (<code>'\u002e'</code>, <small>FULL STOP</small>),
	*
	* <li> The colon character {@code ':'}
	* (<code>'\u003a'</code>, <small>COLON</small>), and
	*
	* <li> The underscore character {@code '_'}
	* (<code>'\u005f'</code>, <small>LOW LINE</small>).
	*
	* </ul>
	*
	* A charset name must begin with either a letter or a digit. The empty string
	* is not a legal charset name. Charset names are not case-sensitive; that is,
	* case is always ignored when comparing charset names. Charset names
	* generally follow the conventions documented in <a
	* href="http://www.ietf.org/rfc/rfc2278.txt"><i>RFC 2278: IANA Charset
	* Registration Procedures</i></a>.
	*
	* <p> Every charset has a <i>canonical name</i> and may also have one or more
	* <i>aliases</i>. The canonical name is returned by the {@link #name() name} method
	* of this class. Canonical names are, by convention, usually in upper case.
	* The aliases of a charset are returned by the {@link #aliases() aliases}
	* method.
	*
	* <p><a id="hn">Some charsets have an <i>historical name</i> that is defined for
	* compatibility with previous versions of the Java platform.</a> A charset's
	* historical name is either its canonical name or one of its aliases. The
	* historical name is returned by the {@code getEncoding()} methods of the
	* {@link java.io.InputStreamReader#getEncoding InputStreamReader} and {@link
	* java.io.OutputStreamWriter#getEncoding OutputStreamWriter} classes.
	*
	* <p><a id="iana"> </a>If a charset listed in the <a
	* href="http://www.iana.org/assignments/character-sets"><i>IANA Charset
	* Registry</i></a> is supported by an implementation of the Java platform then
	* its canonical name must be the name listed in the registry. Many charsets
	* are given more than one name in the registry, in which case the registry
	* identifies one of the names as <i>MIME-preferred</i>. If a charset has more
	* than one registry name then its canonical name must be the MIME-preferred
	* name and the other names in the registry must be valid aliases. If a
	* supported charset is not listed in the IANA registry then its canonical name
	* must begin with one of the strings {@code "X-"} or {@code "x-"}.
	*
	* <p> The IANA charset registry does change over time, and so the canonical
	* name and the aliases of a particular charset may also change over time. To
	* ensure compatibility it is recommended that no alias ever be removed from a
	* charset, and that if the canonical name of a charset is changed then its
	* previous canonical name be made into an alias.
	*
	*
	* <h2><a id="standard">Standard charsets</a></h2>
	*
	*
	* <p> Every implementation of the Java platform is required to support the
	* following standard charsets. Consult the release documentation for your
	* implementation to see if any other charsets are supported. The behavior
	* of such optional charsets may differ between implementations.
	*
	* <blockquote><table class="striped" style="width:80%">
	* <caption style="display:none">Description of standard charsets</caption>
	* <thead>
	* <tr><th scope="col" style="text-align:left">Charset</th><th scope="col" style="text-align:left">Description</th></tr>
	* </thead>
	* <tbody>
	* <tr><th scope="row" style="vertical-align:top">{@code US-ASCII}</th>
	* <td>Seven-bit ASCII, a.k.a. {@code ISO646-US},
	* a.k.a. the Basic Latin block of the Unicode character set</td></tr>
	* <tr><th scope="row" style="vertical-align:top"><code>ISO-8859-1  </code></th>
	* <td>ISO Latin Alphabet No. 1, a.k.a. {@code ISO-LATIN-1}</td></tr>
	* <tr><th scope="row" style="vertical-align:top">{@code UTF-8}</th>
	* <td>Eight-bit UCS Transformation Format</td></tr>
	* <tr><th scope="row" style="vertical-align:top">{@code UTF-16BE}</th>
	* <td>Sixteen-bit UCS Transformation Format,
	* big-endian byte order</td></tr>
	* <tr><th scope="row" style="vertical-align:top">{@code UTF-16LE}</th>
	* <td>Sixteen-bit UCS Transformation Format,
	* little-endian byte order</td></tr>
	* <tr><th scope="row" style="vertical-align:top">{@code UTF-16}</th>
	* <td>Sixteen-bit UCS Transformation Format,
	* byte order identified by an optional byte-order mark</td></tr>
	* </tbody>
	* </table></blockquote>
	*
	* <p> The {@code UTF-8} charset is specified by <a
	* href="http://www.ietf.org/rfc/rfc2279.txt"><i>RFC 2279</i></a>; the
	* transformation format upon which it is based is specified in
	* Amendment 2 of ISO 10646-1 and is also described in the <a
	* href="http://www.unicode.org/standard/standard.html"><i>Unicode
	* Standard</i></a>.
	*
	* <p> The {@code UTF-16} charsets are specified by <a
	* href="http://www.ietf.org/rfc/rfc2781.txt"><i>RFC 2781</i></a>; the
	* transformation formats upon which they are based are specified in
	* Amendment 1 of ISO 10646-1 and are also described in the <a
	* href="http://www.unicode.org/standard/standard.html"><i>Unicode
	* Standard</i></a>.
	*
	* <p> The {@code UTF-16} charsets use sixteen-bit quantities and are
	* therefore sensitive to byte order. In these encodings the byte order of a
	* stream may be indicated by an initial <i>byte-order mark</i> represented by
	* the Unicode character <code>'\uFEFF'</code>. Byte-order marks are handled
	* as follows:
	*
	* <ul>
	*
	* <li><p> When decoding, the {@code UTF-16BE} and {@code UTF-16LE}
	* charsets interpret the initial byte-order marks as a <small>ZERO-WIDTH
	* NON-BREAKING SPACE</small>; when encoding, they do not write
	* byte-order marks. </p></li>
	*
	* <li><p> When decoding, the {@code UTF-16} charset interprets the
	* byte-order mark at the beginning of the input stream to indicate the
	* byte-order of the stream but defaults to big-endian if there is no
	* byte-order mark; when encoding, it uses big-endian byte order and writes
	* a big-endian byte-order mark. </p></li>
	*
	* </ul>
	*
	* In any case, byte order marks occurring after the first element of an
	* input sequence are not omitted since the same code is used to represent
	* <small>ZERO-WIDTH NON-BREAKING SPACE</small>.
	*
	* <p> Every instance of the Java virtual machine has a default charset, which
	* may or may not be one of the standard charsets. The default charset is
	* determined during virtual-machine startup and typically depends upon the
	* locale and charset being used by the underlying operating system. </p>
	*
	* <p> The {@link StandardCharsets} class defines constants for each of the
	* standard charsets.
	*
	* <h2>Terminology</h2>
	*
	* <p> The name of this class is taken from the terms used in
	* <a href="http://www.ietf.org/rfc/rfc2278.txt"><i>RFC 2278</i></a>.
	* In that document a <i>charset</i> is defined as the combination of
	* one or more coded character sets and a character-encoding scheme.
	* (This definition is confusing; some other software systems define
	* <i>charset</i> as a synonym for <i>coded character set</i>.)
	*
	* <p> A <i>coded character set</i> is a mapping between a set of abstract
	* characters and a set of integers. US-ASCII, ISO 8859-1,
	* JIS X 0201, and Unicode are examples of coded character sets.
	*
	* <p> Some standards have defined a <i>character set</i> to be simply a
	* set of abstract characters without an associated assigned numbering.
	* An alphabet is an example of such a character set. However, the subtle
	* distinction between <i>character set</i> and <i>coded character set</i>
	* is rarely used in practice; the former has become a short form for the
	* latter, including in the Java API specification.
	*
	* <p> A <i>character-encoding scheme</i> is a mapping between one or more
	* coded character sets and a set of octet (eight-bit byte) sequences.
	* UTF-8, UTF-16, ISO 2022, and EUC are examples of
	* character-encoding schemes. Encoding schemes are often associated with
	* a particular coded character set; UTF-8, for example, is used only to
	* encode Unicode. Some schemes, however, are associated with multiple
	* coded character sets; EUC, for example, can be used to encode
	* characters in a variety of Asian coded character sets.
	*
	* <p> When a coded character set is used exclusively with a single
	* character-encoding scheme then the corresponding charset is usually
	* named for the coded character set; otherwise a charset is usually named
	* for the encoding scheme and, possibly, the locale of the coded
	* character sets that it supports. Hence {@code US-ASCII} is both the
	* name of a coded character set and of the charset that encodes it, while
	* {@code EUC-JP} is the name of the charset that encodes the
	* JIS X 0201, JIS X 0208, and JIS X 0212
	* coded character sets for the Japanese language.
	*
	* <p> The native character encoding of the Java programming language is
	* UTF-16. A charset in the Java platform therefore defines a mapping
	* between sequences of sixteen-bit UTF-16 code units (that is, sequences
	* of chars) and sequences of bytes. </p>
	*
	*
	* @author Mark Reinhold
	* @author JSR-51 Expert Group
	* @since 1.4
	*
	* @see CharsetDecoder
	* @see CharsetEncoder
	* @see java.nio.charset.spi.CharsetProvider
	* @see java.lang.Character
	*/

	public abstract class Charset
	implements Comparable<Charset>
	{

	/* -- Static methods -- */

	/**
	* Checks that the given string is a legal charset name. </p>
	*
	* @param s
	* A purported charset name
	*
	* @throws IllegalCharsetNameException
	* If the given name is not a legal charset name
	*/
	private static void checkName(String s) {
	int n = s.length();
	if (n == 0) {
	throw new IllegalCharsetNameException(s);
	}
	for (int i = 0; i < n; i++) {
	char c = s.charAt(i);
	if (c >= 'A' && c <= 'Z') continue;
	if (c >= 'a' && c <= 'z') continue;
	if (c >= '0' && c <= '9') continue;
	if (c == '-' && i != 0) continue;
	if (c == '+' && i != 0) continue;
	if (c == ':' && i != 0) continue;
	if (c == '_' && i != 0) continue;
	if (c == '.' && i != 0) continue;
	throw new IllegalCharsetNameException(s);
	}
	}

	/* The standard set of charsets */
	private static final CharsetProvider standardProvider
	= new sun.nio.cs.StandardCharsets();

	private static final String[] zeroAliases = new String[0];

	// Cache of the most-recently-returned charsets,
	// along with the names that were used to find them
	//
	private static volatile Object[] cache1; // "Level 1" cache
	private static volatile Object[] cache2; // "Level 2" cache

	private static void cache(String charsetName, Charset cs) {
	cache2 = cache1;
	cache1 = new Object[] { charsetName, cs };
	}

	// Creates an iterator that walks over the available providers, ignoring
	// those whose lookup or instantiation causes a security exception to be
	// thrown. Should be invoked with full privileges.
	//
	private static Iterator<CharsetProvider> providers() {
	return new Iterator<>() {
	ClassLoader cl = ClassLoader.getSystemClassLoader();
	ServiceLoader<CharsetProvider> sl =
	ServiceLoader.load(CharsetProvider.class, cl);
	Iterator<CharsetProvider> i = sl.iterator();
	CharsetProvider next = null;

	private boolean getNext() {
	while (next == null) {
	try {
	if (!i.hasNext())
	return false;
	next = i.next();
	} catch (ServiceConfigurationError sce) {
	if (sce.getCause() instanceof SecurityException) {
	// Ignore security exceptions
	continue;
	}
	throw sce;
	}
	}
	return true;
	}

	public boolean hasNext() {
	return getNext();
	}

	public CharsetProvider next() {
	if (!getNext())
	throw new NoSuchElementException();
	CharsetProvider n = next;
	next = null;
	return n;
	}

	public void remove() {
	throw new UnsupportedOperationException();
	}

	};
	}

	// Thread-local gate to prevent recursive provider lookups
	private static ThreadLocal<ThreadLocal<?>> gate =
	new ThreadLocal<ThreadLocal<?>>();

	@SuppressWarnings("removal")
	private static Charset lookupViaProviders(final String charsetName) {

	// The runtime startup sequence looks up standard charsets as a
	// consequence of the VM's invocation of System.initializeSystemClass
	// in order to, e.g., set system properties and encode filenames. At
	// that point the application class loader has not been initialized,
	// however, so we can't look for providers because doing so will cause
	// that loader to be prematurely initialized with incomplete
	// information.
	//
	if (!VM.isBooted())
	return null;

	if (gate.get() != null)
	// Avoid recursive provider lookups
	return null;
	try {
	gate.set(gate);

	return AccessController.doPrivileged(
	new PrivilegedAction<>() {
	public Charset run() {
	for (Iterator<CharsetProvider> i = providers();
	i.hasNext();) {
	CharsetProvider cp = i.next();
	Charset cs = cp.charsetForName(charsetName);
	if (cs != null)
	return cs;
	}
	return null;
	}
	});

	} finally {
	gate.set(null);
	}
	}

	/* The extended set of charsets */
	private static class ExtendedProviderHolder {
	static final CharsetProvider[] extendedProviders = extendedProviders();
	// returns ExtendedProvider, if installed
	@SuppressWarnings("removal")
	private static CharsetProvider[] extendedProviders() {
	return AccessController.doPrivileged(new PrivilegedAction<>() {
	public CharsetProvider[] run() {
	CharsetProvider[] cps = new CharsetProvider[1];
	int n = 0;
	ServiceLoader<CharsetProvider> sl =
	ServiceLoader.loadInstalled(CharsetProvider.class);
	for (CharsetProvider cp : sl) {
	if (n + 1 > cps.length) {
	cps = Arrays.copyOf(cps, cps.length << 1);
	}
	cps[n++] = cp;
	}
	return n == cps.length ? cps : Arrays.copyOf(cps, n);
	}});
	}
	}

	private static Charset lookupExtendedCharset(String charsetName) {
	if (!VM.isBooted()) // see lookupViaProviders()
	return null;
	CharsetProvider[] ecps = ExtendedProviderHolder.extendedProviders;
	for (CharsetProvider cp : ecps) {
	Charset cs = cp.charsetForName(charsetName);
	if (cs != null)
	return cs;
	}
	return null;
	}

	private static Charset lookup(String charsetName) {
	if (charsetName == null)
	throw new IllegalArgumentException("Null charset name");
	Object[] a;
	if ((a = cache1) != null && charsetName.equals(a[0]))
	return (Charset)a[1];
	// We expect most programs to use one Charset repeatedly.
	// We convey a hint to this effect to the VM by putting the
	// level 1 cache miss code in a separate method.
	return lookup2(charsetName);
	}

	private static Charset lookup2(String charsetName) {
	Object[] a;
	if ((a = cache2) != null && charsetName.equals(a[0])) {
	cache2 = cache1;
	cache1 = a;
	return (Charset)a[1];
	}
	Charset cs;
	if ((cs = standardProvider.charsetForName(charsetName)) != null \|\|
	(cs = lookupExtendedCharset(charsetName)) != null \|\|
	(cs = lookupViaProviders(charsetName)) != null)
	{
	cache(charsetName, cs);
	return cs;
	}

	/* Only need to check the name if we didn't find a charset for it */
	checkName(charsetName);
	return null;
	}

	/**
	* Tells whether the named charset is supported.
	*
	* @param charsetName
	* The name of the requested charset; may be either
	* a canonical name or an alias
	*
	* @return {@code true} if, and only if, support for the named charset
	* is available in the current Java virtual machine
	*
	* @throws IllegalCharsetNameException
	* If the given charset name is illegal
	*
	* @throws IllegalArgumentException
	* If the given {@code charsetName} is null
	*/
	public static boolean isSupported(String charsetName) {
	return (lookup(charsetName) != null);
	}

	/**
	* Returns a charset object for the named charset.
	*
	* @param charsetName
	* The name of the requested charset; may be either
	* a canonical name or an alias
	*
	* @return A charset object for the named charset
	*
	* @throws IllegalCharsetNameException
	* If the given charset name is illegal
	*
	* @throws IllegalArgumentException
	* If the given {@code charsetName} is null
	*
	* @throws UnsupportedCharsetException
	* If no support for the named charset is available
	* in this instance of the Java virtual machine
	*/
	public static Charset forName(String charsetName) {
	Charset cs = lookup(charsetName);
	if (cs != null)
	return cs;
	throw new UnsupportedCharsetException(charsetName);
	}

	// Fold charsets from the given iterator into the given map, ignoring
	// charsets whose names already have entries in the map.
	//
	private static void put(Iterator<Charset> i, Map<String,Charset> m) {
	while (i.hasNext()) {
	Charset cs = i.next();
	if (!m.containsKey(cs.name()))
	m.put(cs.name(), cs);
	}
	}

	/**
	* Constructs a sorted map from canonical charset names to charset objects.
	*
	* <p> The map returned by this method will have one entry for each charset
	* for which support is available in the current Java virtual machine. If
	* two or more supported charsets have the same canonical name then the
	* resulting map will contain just one of them; which one it will contain
	* is not specified. </p>
	*
	* <p> The invocation of this method, and the subsequent use of the
	* resulting map, may cause time-consuming disk or network I/O operations
	* to occur. This method is provided for applications that need to
	* enumerate all of the available charsets, for example to allow user
	* charset selection. This method is not used by the {@link #forName
	* forName} method, which instead employs an efficient incremental lookup
	* algorithm.
	*
	* <p> This method may return different results at different times if new
	* charset providers are dynamically made available to the current Java
	* virtual machine. In the absence of such changes, the charsets returned
	* by this method are exactly those that can be retrieved via the {@link
	* #forName forName} method. </p>
	*
	* @return An immutable, case-insensitive map from canonical charset names
	* to charset objects
	*/
	@SuppressWarnings("removal")
	public static SortedMap<String,Charset> availableCharsets() {
	return AccessController.doPrivileged(
	new PrivilegedAction<>() {
	public SortedMap<String,Charset> run() {
	TreeMap<String,Charset> m =
	new TreeMap<>(
	String.CASE_INSENSITIVE_ORDER);
	put(standardProvider.charsets(), m);
	CharsetProvider[] ecps = ExtendedProviderHolder.extendedProviders;
	for (CharsetProvider ecp :ecps) {
	put(ecp.charsets(), m);
	}
	for (Iterator<CharsetProvider> i = providers(); i.hasNext();) {
	CharsetProvider cp = i.next();
	put(cp.charsets(), m);
	}
	return Collections.unmodifiableSortedMap(m);
	}
	});
	}

	private static volatile Charset defaultCharset;

	/**
	* Returns the default charset of this Java virtual machine.
	*
	* <p> The default charset is determined during virtual-machine startup and
	* typically depends upon the locale and charset of the underlying
	* operating system.
	*
	* @return A charset object for the default charset
	*
	* @since 1.5
	*/
	public static Charset defaultCharset() {
	if (defaultCharset == null) {
	synchronized (Charset.class) {
	String csn = GetPropertyAction
	.privilegedGetProperty("file.encoding");
	Charset cs = lookup(csn);
	if (cs != null)
	defaultCharset = cs;
	else
	defaultCharset = sun.nio.cs.UTF_8.INSTANCE;
	}
	}
	return defaultCharset;
	}


	/* -- Instance fields and methods -- */

	private final String name; // tickles a bug in oldjavac
	private final String[] aliases; // tickles a bug in oldjavac
	private Set<String> aliasSet = null;

	/**
	* Initializes a new charset with the given canonical name and alias
	* set.
	*
	* @param canonicalName
	* The canonical name of this charset
	*
	* @param aliases
	* An array of this charset's aliases, or null if it has no aliases
	*
	* @throws IllegalCharsetNameException
	* If the canonical name or any of the aliases are illegal
	*/
	protected Charset(String canonicalName, String[] aliases) {
	String[] as = Objects.requireNonNullElse(aliases, zeroAliases);

	// Skip checks for the standard, built-in Charsets we always load
	// during initialization.
	if (canonicalName != "ISO-8859-1"
	&& canonicalName != "US-ASCII"
	&& canonicalName != "UTF-8") {
	checkName(canonicalName);
	for (int i = 0; i < as.length; i++) {
	checkName(as[i]);
	}
	}
	this.name = canonicalName;
	this.aliases = as;
	}

	/**
	* Returns this charset's canonical name.
	*
	* @return The canonical name of this charset
	*/
	public final String name() {
	return name;
	}

	/**
	* Returns a set containing this charset's aliases.
	*
	* @return An immutable set of this charset's aliases
	*/
	public final Set<String> aliases() {
	if (aliasSet != null)
	return aliasSet;
	int n = aliases.length;
	HashSet<String> hs = new HashSet<>(n);
	for (int i = 0; i < n; i++)
	hs.add(aliases[i]);
	aliasSet = Collections.unmodifiableSet(hs);
	return aliasSet;
	}

	/**
	* Returns this charset's human-readable name for the default locale.
	*
	* <p> The default implementation of this method simply returns this
	* charset's canonical name. Concrete subclasses of this class may
	* override this method in order to provide a localized display name. </p>
	*
	* @return The display name of this charset in the default locale
	*/
	public String displayName() {
	return name;
	}

	/**
	* Tells whether or not this charset is registered in the <a
	* href="http://www.iana.org/assignments/character-sets">IANA Charset
	* Registry</a>.
	*
	* @return {@code true} if, and only if, this charset is known by its
	* implementor to be registered with the IANA
	*/
	public final boolean isRegistered() {
	return !name.startsWith("X-") && !name.startsWith("x-");
	}

	/**
	* Returns this charset's human-readable name for the given locale.
	*
	* <p> The default implementation of this method simply returns this
	* charset's canonical name. Concrete subclasses of this class may
	* override this method in order to provide a localized display name. </p>
	*
	* @param locale
	* The locale for which the display name is to be retrieved
	*
	* @return The display name of this charset in the given locale
	*/
	public String displayName(Locale locale) {
	return name;
	}

	/**
	* Tells whether or not this charset contains the given charset.
	*
	* <p> A charset <i>C</i> is said to <i>contain</i> a charset <i>D</i> if,
	* and only if, every character representable in <i>D</i> is also
	* representable in <i>C</i>. If this relationship holds then it is
	* guaranteed that every string that can be encoded in <i>D</i> can also be
	* encoded in <i>C</i> without performing any replacements.
	*
	* <p> That <i>C</i> contains <i>D</i> does not imply that each character
	* representable in <i>C</i> by a particular byte sequence is represented
	* in <i>D</i> by the same byte sequence, although sometimes this is the
	* case.
	*
	* <p> Every charset contains itself.
	*
	* <p> This method computes an approximation of the containment relation:
	* If it returns {@code true} then the given charset is known to be
	* contained by this charset; if it returns {@code false}, however, then
	* it is not necessarily the case that the given charset is not contained
	* in this charset.
	*
	* @param cs
	* The given charset
	*
	* @return {@code true} if the given charset is contained in this charset
	*/
	public abstract boolean contains(Charset cs);

	/**
	* Constructs a new decoder for this charset.
	*
	* @return A new decoder for this charset
	*/
	public abstract CharsetDecoder newDecoder();

	/**
	* Constructs a new encoder for this charset.
	*
	* @return A new encoder for this charset
	*
	* @throws UnsupportedOperationException
	* If this charset does not support encoding
	*/
	public abstract CharsetEncoder newEncoder();

	/**
	* Tells whether or not this charset supports encoding.
	*
	* <p> Nearly all charsets support encoding. The primary exceptions are
	* special-purpose <i>auto-detect</i> charsets whose decoders can determine
	* which of several possible encoding schemes is in use by examining the
	* input byte sequence. Such charsets do not support encoding because
	* there is no way to determine which encoding should be used on output.
	* Implementations of such charsets should override this method to return
	* {@code false}. </p>
	*
	* @return {@code true} if, and only if, this charset supports encoding
	*/
	public boolean canEncode() {
	return true;
	}

	/**
	* Convenience method that decodes bytes in this charset into Unicode
	* characters.
	*
	* <p> An invocation of this method upon a charset {@code cs} returns the
	* same result as the expression
	*
	* <pre>
	* cs.newDecoder()
	* .onMalformedInput(CodingErrorAction.REPLACE)
	* .onUnmappableCharacter(CodingErrorAction.REPLACE)
	* .decode(bb); </pre>
	*
	* except that it is potentially more efficient because it can cache
	* decoders between successive invocations.
	*
	* <p> This method always replaces malformed-input and unmappable-character
	* sequences with this charset's default replacement byte array. In order
	* to detect such sequences, use the {@link
	* CharsetDecoder#decode(java.nio.ByteBuffer)} method directly. </p>
	*
	* @param bb The byte buffer to be decoded
	*
	* @return A char buffer containing the decoded characters
	*/
	public final CharBuffer decode(ByteBuffer bb) {
	try {
	return ThreadLocalCoders.decoderFor(this)
	.onMalformedInput(CodingErrorAction.REPLACE)
	.onUnmappableCharacter(CodingErrorAction.REPLACE)
	.decode(bb);
	} catch (CharacterCodingException x) {
	throw new Error(x); // Can't happen
	}
	}

	/**
	* Convenience method that encodes Unicode characters into bytes in this
	* charset.
	*
	* <p> An invocation of this method upon a charset {@code cs} returns the
	* same result as the expression
	*
	* <pre>
	* cs.newEncoder()
	* .onMalformedInput(CodingErrorAction.REPLACE)
	* .onUnmappableCharacter(CodingErrorAction.REPLACE)
	* .encode(bb); </pre>
	*
	* except that it is potentially more efficient because it can cache
	* encoders between successive invocations.
	*
	* <p> This method always replaces malformed-input and unmappable-character
	* sequences with this charset's default replacement string. In order to
	* detect such sequences, use the {@link
	* CharsetEncoder#encode(java.nio.CharBuffer)} method directly. </p>
	*
	* @param cb The char buffer to be encoded
	*
	* @return A byte buffer containing the encoded characters
	*/
	public final ByteBuffer encode(CharBuffer cb) {
	try {
	return ThreadLocalCoders.encoderFor(this)
	.onMalformedInput(CodingErrorAction.REPLACE)
	.onUnmappableCharacter(CodingErrorAction.REPLACE)
	.encode(cb);
	} catch (CharacterCodingException x) {
	throw new Error(x); // Can't happen
	}
	}

	/**
	* Convenience method that encodes a string into bytes in this charset.
	*
	* <p> An invocation of this method upon a charset {@code cs} returns the
	* same result as the expression
	*
	* <pre>
	* cs.encode(CharBuffer.wrap(s)); </pre>
	*
	* @param str The string to be encoded
	*
	* @return A byte buffer containing the encoded characters
	*/
	public final ByteBuffer encode(String str) {
	return encode(CharBuffer.wrap(str));
	}

	/**
	* Compares this charset to another.
	*
	* <p> Charsets are ordered by their canonical names, without regard to
	* case. </p>
	*
	* @param that
	* The charset to which this charset is to be compared
	*
	* @return A negative integer, zero, or a positive integer as this charset
	* is less than, equal to, or greater than the specified charset
	*/
	public final int compareTo(Charset that) {
	return (name().compareToIgnoreCase(that.name()));
	}

	/**
	* Computes a hashcode for this charset.
	*
	* @return An integer hashcode
	*/
	public final int hashCode() {
	return name().hashCode();
	}

	/**
	* Tells whether or not this object is equal to another.
	*
	* <p> Two charsets are equal if, and only if, they have the same canonical
	* names. A charset is never equal to any other type of object. </p>
	*
	* @return {@code true} if, and only if, this charset is equal to the
	* given object
	*/
	public final boolean equals(Object ob) {
	if (!(ob instanceof Charset))
	return false;
	if (this == ob)
	return true;
	return name.equals(((Charset)ob).name());
	}

	/**
	* Returns a string describing this charset.
	*
	* @return A string describing this charset
	*/
	public final String toString() {
	return name();
	}

	}

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