/*
* Copyright 2000-2006 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
// -- This file was mechanically generated: Do not edit! -- //
package java.nio.charset;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.BufferOverflowException;
import java.nio.BufferUnderflowException;
import java.lang.ref.WeakReference;
import java.nio.charset.CoderMalfunctionError; // javadoc
/**
* An engine that can transform a sequence of bytes in a specific charset into a sequence of
* sixteen-bit Unicode characters.
*
* <a name="steps">
*
* <p> The input byte sequence is provided in a byte buffer or a series
* of such buffers. The output character sequence is written to a character buffer
* or a series of such buffers. A decoder should always be used by making
* the following sequence of method invocations, hereinafter referred to as a
* <i>decoding operation</i>:
*
* <ol>
*
* <li><p> Reset the decoder via the {@link #reset reset} method, unless it
* has not been used before; </p></li>
*
* <li><p> Invoke the {@link #decode decode} method zero or more times, as
* long as additional input may be available, passing <tt>false</tt> for the
* <tt>endOfInput</tt> argument and filling the input buffer and flushing the
* output buffer between invocations; </p></li>
*
* <li><p> Invoke the {@link #decode decode} method one final time, passing
* <tt>true</tt> for the <tt>endOfInput</tt> argument; and then </p></li>
*
* <li><p> Invoke the {@link #flush flush} method so that the decoder can
* flush any internal state to the output buffer. </p></li>
*
* </ol>
*
* Each invocation of the {@link #decode decode} method will decode as many
* bytes as possible from the input buffer, writing the resulting characters
* to the output buffer. The {@link #decode decode} method returns when more
* input is required, when there is not enough room in the output buffer, or
* when a decoding error has occurred. In each case a {@link CoderResult}
* object is returned to describe the reason for termination. An invoker can
* examine this object and fill the input buffer, flush the output buffer, or
* attempt to recover from a decoding error, as appropriate, and try again.
*
* <a name="ce">
*
* <p> There are two general types of decoding errors. If the input byte
* sequence is not legal for this charset then the input is considered <i>malformed</i>. If
* the input byte sequence is legal but cannot be mapped to a valid
* Unicode character then an <i>unmappable character</i> has been encountered.
*
* <a name="cae">
*
* <p> How a decoding error is handled depends upon the action requested for
* that type of error, which is described by an instance of the {@link
* CodingErrorAction} class. The possible error actions are to {@link
* CodingErrorAction#IGNORE </code>ignore<code>} the erroneous input, {@link
* CodingErrorAction#REPORT </code>report<code>} the error to the invoker via
* the returned {@link CoderResult} object, or {@link CodingErrorAction#REPLACE
* </code>replace<code>} the erroneous input with the current value of the
* replacement string. The replacement
*
* has the initial value <tt>"\uFFFD"</tt>;
*
* its value may be changed via the {@link #replaceWith(java.lang.String)
* replaceWith} method.
*
* <p> The default action for malformed-input and unmappable-character errors
* is to {@link CodingErrorAction#REPORT </code>report<code>} them. The
* malformed-input error action may be changed via the {@link
* #onMalformedInput(CodingErrorAction) onMalformedInput} method; the
* unmappable-character action may be changed via the {@link
* #onUnmappableCharacter(CodingErrorAction) onUnmappableCharacter} method.
*
* <p> This class is designed to handle many of the details of the decoding
* process, including the implementation of error actions. A decoder for a
* specific charset, which is a concrete subclass of this class, need only
* implement the abstract {@link #decodeLoop decodeLoop} method, which
* encapsulates the basic decoding loop. A subclass that maintains internal
* state should, additionally, override the {@link #implFlush implFlush} and
* {@link #implReset implReset} methods.
*
* <p> Instances of this class are not safe for use by multiple concurrent
* threads. </p>
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @since 1.4
*
* @see ByteBuffer
* @see CharBuffer
* @see Charset
* @see CharsetEncoder
*/
public abstract class CharsetDecoder {
private final Charset charset;
private final float averageCharsPerByte;
private final float maxCharsPerByte;
private String replacement;
private CodingErrorAction malformedInputAction
= CodingErrorAction.REPORT;
private CodingErrorAction unmappableCharacterAction
= CodingErrorAction.REPORT;
// Internal states
//
private static final int ST_RESET = 0;
private static final int ST_CODING = 1;
private static final int ST_END = 2;
private static final int ST_FLUSHED = 3;
private int state = ST_RESET;
private static String stateNames[]
= { "RESET", "CODING", "CODING_END", "FLUSHED" };
/**
* Initializes a new decoder. The new decoder will have the given
* chars-per-byte and replacement values. </p>
*
* @param averageCharsPerByte
* A positive float value indicating the expected number of
* characters that will be produced for each input byte
*
* @param maxCharsPerByte
* A positive float value indicating the maximum number of
* characters that will be produced for each input byte
*
* @param replacement
* The initial replacement; must not be <tt>null</tt>, must have
* non-zero length, must not be longer than maxCharsPerByte,
* and must be {@link #isLegalReplacement </code>legal<code>}
*
* @throws IllegalArgumentException
* If the preconditions on the parameters do not hold
*/
private
CharsetDecoder(Charset cs,
float averageCharsPerByte,
float maxCharsPerByte,
String replacement)
{
this.charset = cs;
if (averageCharsPerByte <= 0.0f)
throw new IllegalArgumentException("Non-positive "
+ "averageCharsPerByte");
if (maxCharsPerByte <= 0.0f)
throw new IllegalArgumentException("Non-positive "
+ "maxCharsPerByte");
if (!Charset.atBugLevel("1.4")) {
if (averageCharsPerByte > maxCharsPerByte)
throw new IllegalArgumentException("averageCharsPerByte"
+ " exceeds "
+ "maxCharsPerByte");
}
this.replacement = replacement;
this.averageCharsPerByte = averageCharsPerByte;
this.maxCharsPerByte = maxCharsPerByte;
replaceWith(replacement);
}
/**
* Initializes a new decoder. The new decoder will have the given
* chars-per-byte values and its replacement will be the
* string <tt>"\uFFFD"</tt>. </p>
*
* @param averageCharsPerByte
* A positive float value indicating the expected number of
* characters that will be produced for each input byte
*
* @param maxCharsPerByte
* A positive float value indicating the maximum number of
* characters that will be produced for each input byte
*
* @throws IllegalArgumentException
* If the preconditions on the parameters do not hold
*/
protected CharsetDecoder(Charset cs,
float averageCharsPerByte,
float maxCharsPerByte)
{
this(cs,
averageCharsPerByte, maxCharsPerByte,
"\uFFFD");
}
/**
* Returns the charset that created this decoder. </p>
*
* @return This decoder's charset
*/
public final Charset charset() {
return charset;
}
/**
* Returns this decoder's replacement value. </p>
*
* @return This decoder's current replacement,
* which is never <tt>null</tt> and is never empty
*/
public final String replacement() {
return replacement;
}
/**
* Changes this decoder's replacement value.
*
* <p> This method invokes the {@link #implReplaceWith implReplaceWith}
* method, passing the new replacement, after checking that the new
* replacement is acceptable. </p>
*
* @param newReplacement
*
* The new replacement; must not be <tt>null</tt>
* and must have non-zero length
*
* @return This decoder
*
* @throws IllegalArgumentException
* If the preconditions on the parameter do not hold
*/
public final CharsetDecoder replaceWith(String newReplacement) {
if (newReplacement == null)
throw new IllegalArgumentException("Null replacement");
int len = newReplacement.length();
if (len == 0)
throw new IllegalArgumentException("Empty replacement");
if (len > maxCharsPerByte)
throw new IllegalArgumentException("Replacement too long");
this.replacement = newReplacement;
implReplaceWith(newReplacement);
return this;
}
/**
* Reports a change to this decoder's replacement value.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by decoders that require notification of changes to
* the replacement. </p>
*
* @param newReplacement
*/
protected void implReplaceWith(String newReplacement) {
}
/**
* Returns this decoder's current action for malformed-input errors. </p>
*
* @return The current malformed-input action, which is never <tt>null</tt>
*/
public CodingErrorAction malformedInputAction() {
return malformedInputAction;
}
/**
* Changes this decoder's action for malformed-input errors. </p>
*
* <p> This method invokes the {@link #implOnMalformedInput
* implOnMalformedInput} method, passing the new action. </p>
*
* @param newAction The new action; must not be <tt>null</tt>
*
* @return This decoder
*
* @throws IllegalArgumentException
* If the precondition on the parameter does not hold
*/
public final CharsetDecoder onMalformedInput(CodingErrorAction newAction) {
if (newAction == null)
throw new IllegalArgumentException("Null action");
malformedInputAction = newAction;
implOnMalformedInput(newAction);
return this;
}
/**
* Reports a change to this decoder's malformed-input action.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by decoders that require notification of changes to
* the malformed-input action. </p>
*/
protected void implOnMalformedInput(CodingErrorAction newAction) { }
/**
* Returns this decoder's current action for unmappable-character errors.
* </p>
*
* @return The current unmappable-character action, which is never
* <tt>null</tt>
*/
public CodingErrorAction unmappableCharacterAction() {
return unmappableCharacterAction;
}
/**
* Changes this decoder's action for unmappable-character errors.
*
* <p> This method invokes the {@link #implOnUnmappableCharacter
* implOnUnmappableCharacter} method, passing the new action. </p>
*
* @param newAction The new action; must not be <tt>null</tt>
*
* @return This decoder
*
* @throws IllegalArgumentException
* If the precondition on the parameter does not hold
*/
public final CharsetDecoder onUnmappableCharacter(CodingErrorAction
newAction)
{
if (newAction == null)
throw new IllegalArgumentException("Null action");
unmappableCharacterAction = newAction;
implOnUnmappableCharacter(newAction);
return this;
}
/**
* Reports a change to this decoder's unmappable-character action.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by decoders that require notification of changes to
* the unmappable-character action. </p>
*/
protected void implOnUnmappableCharacter(CodingErrorAction newAction) { }
/**
* Returns the average number of characters that will be produced for each
* byte of input. This heuristic value may be used to estimate the size
* of the output buffer required for a given input sequence. </p>
*
* @return The average number of characters produced
* per byte of input
*/
public final float averageCharsPerByte() {
return averageCharsPerByte;
}
/**
* Returns the maximum number of characters that will be produced for each
* byte of input. This value may be used to compute the worst-case size
* of the output buffer required for a given input sequence. </p>
*
* @return The maximum number of characters that will be produced per
* byte of input
*/
public final float maxCharsPerByte() {
return maxCharsPerByte;
}
/**
* Decodes as many bytes as possible from the given input buffer,
* writing the results to the given output buffer.
*
* <p> The buffers are read from, and written to, starting at their current
* positions. At most {@link Buffer#remaining in.remaining()} bytes
* will be read and at most {@link Buffer#remaining out.remaining()}
* characters will be written. The buffers' positions will be advanced to
* reflect the bytes read and the characters written, but their marks and
* limits will not be modified.
*
* <p> In addition to reading bytes from the input buffer and writing
* characters to the output buffer, this method returns a {@link CoderResult}
* object to describe its reason for termination:
*
* <ul>
*
* <li><p> {@link CoderResult#UNDERFLOW} indicates that as much of the
* input buffer as possible has been decoded. If there is no further
* input then the invoker can proceed to the next step of the
* <a href="#steps">decoding operation</a>. Otherwise this method
* should be invoked again with further input. </p></li>
*
* <li><p> {@link CoderResult#OVERFLOW} indicates that there is
* insufficient space in the output buffer to decode any more bytes.
* This method should be invoked again with an output buffer that has
* more {@linkplain Buffer#remaining remaining} characters. This is
* typically done by draining any decoded characters from the output
* buffer. </p></li>
*
* <li><p> A {@link CoderResult#malformedForLength
* </code>malformed-input<code>} result indicates that a malformed-input
* error has been detected. The malformed bytes begin at the input
* buffer's (possibly incremented) position; the number of malformed
* bytes may be determined by invoking the result object's {@link
* CoderResult#length() length} method. This case applies only if the
* {@link #onMalformedInput </code>malformed action<code>} of this decoder
* is {@link CodingErrorAction#REPORT}; otherwise the malformed input
* will be ignored or replaced, as requested. </p></li>
*
* <li><p> An {@link CoderResult#unmappableForLength
* </code>unmappable-character<code>} result indicates that an
* unmappable-character error has been detected. The bytes that
* decode the unmappable character begin at the input buffer's (possibly
* incremented) position; the number of such bytes may be determined
* by invoking the result object's {@link CoderResult#length() length}
* method. This case applies only if the {@link #onUnmappableCharacter
* </code>unmappable action<code>} of this decoder is {@link
* CodingErrorAction#REPORT}; otherwise the unmappable character will be
* ignored or replaced, as requested. </p></li>
*
* </ul>
*
* In any case, if this method is to be reinvoked in the same decoding
* operation then care should be taken to preserve any bytes remaining
* in the input buffer so that they are available to the next invocation.
*
* <p> The <tt>endOfInput</tt> parameter advises this method as to whether
* the invoker can provide further input beyond that contained in the given
* input buffer. If there is a possibility of providing additional input
* then the invoker should pass <tt>false</tt> for this parameter; if there
* is no possibility of providing further input then the invoker should
* pass <tt>true</tt>. It is not erroneous, and in fact it is quite
* common, to pass <tt>false</tt> in one invocation and later discover that
* no further input was actually available. It is critical, however, that
* the final invocation of this method in a sequence of invocations always
* pass <tt>true</tt> so that any remaining undecoded input will be treated
* as being malformed.
*
* <p> This method works by invoking the {@link #decodeLoop decodeLoop}
* method, interpreting its results, handling error conditions, and
* reinvoking it as necessary. </p>
*
*
* @param in
* The input byte buffer
*
* @param out
* The output character buffer
*
* @param endOfInput
* <tt>true</tt> if, and only if, the invoker can provide no
* additional input bytes beyond those in the given buffer
*
* @return A coder-result object describing the reason for termination
*
* @throws IllegalStateException
* If a decoding operation is already in progress and the previous
* step was an invocation neither of the {@link #reset reset}
* method, nor of this method with a value of <tt>false</tt> for
* the <tt>endOfInput</tt> parameter, nor of this method with a
* value of <tt>true</tt> for the <tt>endOfInput</tt> parameter
* but a return value indicating an incomplete decoding operation
*
* @throws CoderMalfunctionError
* If an invocation of the decodeLoop method threw
* an unexpected exception
*/
public final CoderResult decode(ByteBuffer in, CharBuffer out,
boolean endOfInput)
{
int newState = endOfInput ? ST_END : ST_CODING;
if ((state != ST_RESET) && (state != ST_CODING)
&& !(endOfInput && (state == ST_END)))
throwIllegalStateException(state, newState);
state = newState;
for (;;) {
CoderResult cr;
try {
cr = decodeLoop(in, out);
} catch (BufferUnderflowException x) {
throw new CoderMalfunctionError(x);
} catch (BufferOverflowException x) {
throw new CoderMalfunctionError(x);
}
if (cr.isOverflow())
return cr;
if (cr.isUnderflow()) {
if (endOfInput && in.hasRemaining()) {
cr = CoderResult.malformedForLength(in.remaining());
// Fall through to malformed-input case
} else {
return cr;
}
}
CodingErrorAction action = null;
if (cr.isMalformed())
action = malformedInputAction;
else if (cr.isUnmappable())
action = unmappableCharacterAction;
else
assert false : cr.toString();
if (action == CodingErrorAction.REPORT)
return cr;
if (action == CodingErrorAction.REPLACE) {
if (out.remaining() < replacement.length())
return CoderResult.OVERFLOW;
out.put(replacement);
}
if ((action == CodingErrorAction.IGNORE)
|| (action == CodingErrorAction.REPLACE)) {
// Skip erroneous input either way
in.position(in.position() + cr.length());
continue;
}
assert false;
}
}
/**
* Flushes this decoder.
*
* <p> Some decoders maintain internal state and may need to write some
* final characters to the output buffer once the overall input sequence has
* been read.
*
* <p> Any additional output is written to the output buffer beginning at
* its current position. At most {@link Buffer#remaining out.remaining()}
* characters will be written. The buffer's position will be advanced
* appropriately, but its mark and limit will not be modified.
*
* <p> If this method completes successfully then it returns {@link
* CoderResult#UNDERFLOW}. If there is insufficient room in the output
* buffer then it returns {@link CoderResult#OVERFLOW}. If this happens
* then this method must be invoked again, with an output buffer that has
* more room, in order to complete the current <a href="#steps">decoding
* operation</a>.
*
* <p> If this decoder has already been flushed then invoking this method
* has no effect.
*
* <p> This method invokes the {@link #implFlush implFlush} method to
* perform the actual flushing operation. </p>
*
* @param out
* The output character buffer
*
* @return A coder-result object, either {@link CoderResult#UNDERFLOW} or
* {@link CoderResult#OVERFLOW}
*
* @throws IllegalStateException
* If the previous step of the current decoding operation was an
* invocation neither of the {@link #flush flush} method nor of
* the three-argument {@link
* #decode(ByteBuffer,CharBuffer,boolean) decode} method
* with a value of <tt>true</tt> for the <tt>endOfInput</tt>
* parameter
*/
public final CoderResult flush(CharBuffer out) {
if (state == ST_END) {
CoderResult cr = implFlush(out);
if (cr.isUnderflow())
state = ST_FLUSHED;
return cr;
}
if (state != ST_FLUSHED)
throwIllegalStateException(state, ST_FLUSHED);
return CoderResult.UNDERFLOW; // Already flushed
}
/**
* Flushes this decoder.
*
* <p> The default implementation of this method does nothing, and always
* returns {@link CoderResult#UNDERFLOW}. This method should be overridden
* by decoders that may need to write final characters to the output buffer
* once the entire input sequence has been read. </p>
*
* @param out
* The output character buffer
*
* @return A coder-result object, either {@link CoderResult#UNDERFLOW} or
* {@link CoderResult#OVERFLOW}
*/
protected CoderResult implFlush(CharBuffer out) {
return CoderResult.UNDERFLOW;
}
/**
* Resets this decoder, clearing any internal state.
*
* <p> This method resets charset-independent state and also invokes the
* {@link #implReset() implReset} method in order to perform any
* charset-specific reset actions. </p>
*
* @return This decoder
*
*/
public final CharsetDecoder reset() {
implReset();
state = ST_RESET;
return this;
}
/**
* Resets this decoder, clearing any charset-specific internal state.
*
* <p> The default implementation of this method does nothing. This method
* should be overridden by decoders that maintain internal state. </p>
*/
protected void implReset() { }
/**
* Decodes one or more bytes into one or more characters.
*
* <p> This method encapsulates the basic decoding loop, decoding as many
* bytes as possible until it either runs out of input, runs out of room
* in the output buffer, or encounters a decoding error. This method is
* invoked by the {@link #decode decode} method, which handles result
* interpretation and error recovery.
*
* <p> The buffers are read from, and written to, starting at their current
* positions. At most {@link Buffer#remaining in.remaining()} bytes
* will be read, and at most {@link Buffer#remaining out.remaining()}
* characters will be written. The buffers' positions will be advanced to
* reflect the bytes read and the characters written, but their marks and
* limits will not be modified.
*
* <p> This method returns a {@link CoderResult} object to describe its
* reason for termination, in the same manner as the {@link #decode decode}
* method. Most implementations of this method will handle decoding errors
* by returning an appropriate result object for interpretation by the
* {@link #decode decode} method. An optimized implementation may instead
* examine the relevant error action and implement that action itself.
*
* <p> An implementation of this method may perform arbitrary lookahead by
* returning {@link CoderResult#UNDERFLOW} until it receives sufficient
* input. </p>
*
* @param in
* The input byte buffer
*
* @param out
* The output character buffer
*
* @return A coder-result object describing the reason for termination
*/
protected abstract CoderResult decodeLoop(ByteBuffer in,
CharBuffer out);
/**
* Convenience method that decodes the remaining content of a single input
* byte buffer into a newly-allocated character buffer.
*
* <p> This method implements an entire <a href="#steps">decoding
* operation</a>; that is, it resets this decoder, then it decodes the
* bytes in the given byte buffer, and finally it flushes this
* decoder. This method should therefore not be invoked if a decoding
* operation is already in progress. </p>
*
* @param in
* The input byte buffer
*
* @return A newly-allocated character buffer containing the result of the
* decoding operation. The buffer's position will be zero and its
* limit will follow the last character written.
*
* @throws IllegalStateException
* If a decoding operation is already in progress
*
* @throws MalformedInputException
* If the byte sequence starting at the input buffer's current
* position is not legal for this charset and the current malformed-input action
* is {@link CodingErrorAction#REPORT}
*
* @throws UnmappableCharacterException
* If the byte sequence starting at the input buffer's current
* position cannot be mapped to an equivalent character sequence and
* the current unmappable-character action is {@link
* CodingErrorAction#REPORT}
*/
public final CharBuffer decode(ByteBuffer in)
throws CharacterCodingException
{
int n = (int)(in.remaining() * averageCharsPerByte());
CharBuffer out = CharBuffer.allocate(n);
if ((n == 0) && (in.remaining() == 0))
return out;
reset();
for (;;) {
CoderResult cr = in.hasRemaining() ?
decode(in, out, true) : CoderResult.UNDERFLOW;
if (cr.isUnderflow())
cr = flush(out);
if (cr.isUnderflow())
break;
if (cr.isOverflow()) {
n = 2*n + 1; // Ensure progress; n might be 0!
CharBuffer o = CharBuffer.allocate(n);
out.flip();
o.put(out);
out = o;
continue;
}
cr.throwException();
}
out.flip();
return out;
}
/**
* Tells whether or not this decoder implements an auto-detecting charset.
*
* <p> The default implementation of this method always returns
* <tt>false</tt>; it should be overridden by auto-detecting decoders to
* return <tt>true</tt>. </p>
*
* @return <tt>true</tt> if, and only if, this decoder implements an
* auto-detecting charset
*/
public boolean isAutoDetecting() {
return false;
}
/**
* Tells whether or not this decoder has yet detected a
* charset <i>(optional operation)</i>.
*
* <p> If this decoder implements an auto-detecting charset then at a
* single point during a decoding operation this method may start returning
* <tt>true</tt> to indicate that a specific charset has been detected in
* the input byte sequence. Once this occurs, the {@link #detectedCharset
* detectedCharset} method may be invoked to retrieve the detected charset.
*
* <p> That this method returns <tt>false</tt> does not imply that no bytes
* have yet been decoded. Some auto-detecting decoders are capable of
* decoding some, or even all, of an input byte sequence without fixing on
* a particular charset.
*
* <p> The default implementation of this method always throws an {@link
* UnsupportedOperationException}; it should be overridden by
* auto-detecting decoders to return <tt>true</tt> once the input charset
* has been determined. </p>
*
* @return <tt>true</tt> if, and only if, this decoder has detected a
* specific charset
*
* @throws UnsupportedOperationException
* If this decoder does not implement an auto-detecting charset
*/
public boolean isCharsetDetected() {
throw new UnsupportedOperationException();
}
/**
* Retrieves the charset that was detected by this
* decoder <i>(optional operation)</i>.
*
* <p> If this decoder implements an auto-detecting charset then this
* method returns the actual charset once it has been detected. After that
* point, this method returns the same value for the duration of the
* current decoding operation. If not enough input bytes have yet been
* read to determine the actual charset then this method throws an {@link
* IllegalStateException}.
*
* <p> The default implementation of this method always throws an {@link
* UnsupportedOperationException}; it should be overridden by
* auto-detecting decoders to return the appropriate value. </p>
*
* @return The charset detected by this auto-detecting decoder,
* or <tt>null</tt> if the charset has not yet been determined
*
* @throws IllegalStateException
* If insufficient bytes have been read to determine a charset
*
* @throws UnsupportedOperationException
* If this decoder does not implement an auto-detecting charset
*/
public Charset detectedCharset() {
throw new UnsupportedOperationException();
}
private void throwIllegalStateException(int from, int to) {
throw new IllegalStateException("Current state = " + stateNames[from]
+ ", new state = " + stateNames[to]);
}
}