2 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
26 // -- This file was mechanically generated: Do not edit! -- //
28 package java.nio.charset;
30 import java.nio.Buffer;
31 import java.nio.ByteBuffer;
32 import java.nio.CharBuffer;
33 import java.nio.BufferOverflowException;
34 import java.nio.BufferUnderflowException;
35 import java.lang.ref.WeakReference;
36 import java.nio.charset.CoderMalfunctionError; // javadoc
40 * An engine that can transform a sequence of sixteen-bit Unicode characters into a sequence of
41 * bytes in a specific charset.
45 * <p> The input character sequence is provided in a character buffer or a series
46 * of such buffers. The output byte sequence is written to a byte buffer
47 * or a series of such buffers. An encoder should always be used by making
48 * the following sequence of method invocations, hereinafter referred to as an
49 * <i>encoding operation</i>:
53 * <li><p> Reset the encoder via the {@link #reset reset} method, unless it
54 * has not been used before; </p></li>
56 * <li><p> Invoke the {@link #encode encode} method zero or more times, as
57 * long as additional input may be available, passing <tt>false</tt> for the
58 * <tt>endOfInput</tt> argument and filling the input buffer and flushing the
59 * output buffer between invocations; </p></li>
61 * <li><p> Invoke the {@link #encode encode} method one final time, passing
62 * <tt>true</tt> for the <tt>endOfInput</tt> argument; and then </p></li>
64 * <li><p> Invoke the {@link #flush flush} method so that the encoder can
65 * flush any internal state to the output buffer. </p></li>
69 * Each invocation of the {@link #encode encode} method will encode as many
70 * characters as possible from the input buffer, writing the resulting bytes
71 * to the output buffer. The {@link #encode encode} method returns when more
72 * input is required, when there is not enough room in the output buffer, or
73 * when an encoding error has occurred. In each case a {@link CoderResult}
74 * object is returned to describe the reason for termination. An invoker can
75 * examine this object and fill the input buffer, flush the output buffer, or
76 * attempt to recover from an encoding error, as appropriate, and try again.
80 * <p> There are two general types of encoding errors. If the input character
81 * sequence is not a legal sixteen-bit Unicode sequence then the input is considered <i>malformed</i>. If
82 * the input character sequence is legal but cannot be mapped to a valid
83 * byte sequence in the given charset then an <i>unmappable character</i> has been encountered.
87 * <p> How an encoding error is handled depends upon the action requested for
88 * that type of error, which is described by an instance of the {@link
89 * CodingErrorAction} class. The possible error actions are to {@link
90 * CodingErrorAction#IGNORE </code>ignore<code>} the erroneous input, {@link
91 * CodingErrorAction#REPORT </code>report<code>} the error to the invoker via
92 * the returned {@link CoderResult} object, or {@link CodingErrorAction#REPLACE
93 * </code>replace<code>} the erroneous input with the current value of the
94 * replacement byte array. The replacement
97 * is initially set to the encoder's default replacement, which often
98 * (but not always) has the initial value <tt>{</tt> <tt>(byte)'?'</tt> <tt>}</tt>;
104 * its value may be changed via the {@link #replaceWith(byte[])
105 * replaceWith} method.
107 * <p> The default action for malformed-input and unmappable-character errors
108 * is to {@link CodingErrorAction#REPORT </code>report<code>} them. The
109 * malformed-input error action may be changed via the {@link
110 * #onMalformedInput(CodingErrorAction) onMalformedInput} method; the
111 * unmappable-character action may be changed via the {@link
112 * #onUnmappableCharacter(CodingErrorAction) onUnmappableCharacter} method.
114 * <p> This class is designed to handle many of the details of the encoding
115 * process, including the implementation of error actions. An encoder for a
116 * specific charset, which is a concrete subclass of this class, need only
117 * implement the abstract {@link #encodeLoop encodeLoop} method, which
118 * encapsulates the basic encoding loop. A subclass that maintains internal
119 * state should, additionally, override the {@link #implFlush implFlush} and
120 * {@link #implReset implReset} methods.
122 * <p> Instances of this class are not safe for use by multiple concurrent
126 * @author Mark Reinhold
127 * @author JSR-51 Expert Group
133 * @see CharsetDecoder
136 public abstract class CharsetEncoder {
138 private final Charset charset;
139 private final float averageBytesPerChar;
140 private final float maxBytesPerChar;
142 private byte[] replacement;
143 private CodingErrorAction malformedInputAction
144 = CodingErrorAction.REPORT;
145 private CodingErrorAction unmappableCharacterAction
146 = CodingErrorAction.REPORT;
150 private static final int ST_RESET = 0;
151 private static final int ST_CODING = 1;
152 private static final int ST_END = 2;
153 private static final int ST_FLUSHED = 3;
155 private int state = ST_RESET;
157 private static String stateNames[]
158 = { "RESET", "CODING", "CODING_END", "FLUSHED" };
162 * Initializes a new encoder. The new encoder will have the given
163 * bytes-per-char and replacement values. </p>
165 * @param averageBytesPerChar
166 * A positive float value indicating the expected number of
167 * bytes that will be produced for each input character
169 * @param maxBytesPerChar
170 * A positive float value indicating the maximum number of
171 * bytes that will be produced for each input character
174 * The initial replacement; must not be <tt>null</tt>, must have
175 * non-zero length, must not be longer than maxBytesPerChar,
176 * and must be {@link #isLegalReplacement </code>legal<code>}
178 * @throws IllegalArgumentException
179 * If the preconditions on the parameters do not hold
182 CharsetEncoder(Charset cs,
183 float averageBytesPerChar,
184 float maxBytesPerChar,
188 if (averageBytesPerChar <= 0.0f)
189 throw new IllegalArgumentException("Non-positive "
190 + "averageBytesPerChar");
191 if (maxBytesPerChar <= 0.0f)
192 throw new IllegalArgumentException("Non-positive "
193 + "maxBytesPerChar");
194 if (!Charset.atBugLevel("1.4")) {
195 if (averageBytesPerChar > maxBytesPerChar)
196 throw new IllegalArgumentException("averageBytesPerChar"
198 + "maxBytesPerChar");
200 this.replacement = replacement;
201 this.averageBytesPerChar = averageBytesPerChar;
202 this.maxBytesPerChar = maxBytesPerChar;
203 replaceWith(replacement);
207 * Initializes a new encoder. The new encoder will have the given
208 * bytes-per-char values and its replacement will be the
209 * byte array <tt>{</tt> <tt>(byte)'?'</tt> <tt>}</tt>. </p>
211 * @param averageBytesPerChar
212 * A positive float value indicating the expected number of
213 * bytes that will be produced for each input character
215 * @param maxBytesPerChar
216 * A positive float value indicating the maximum number of
217 * bytes that will be produced for each input character
219 * @throws IllegalArgumentException
220 * If the preconditions on the parameters do not hold
222 protected CharsetEncoder(Charset cs,
223 float averageBytesPerChar,
224 float maxBytesPerChar)
227 averageBytesPerChar, maxBytesPerChar,
228 new byte[] { (byte)'?' });
232 * Returns the charset that created this encoder. </p>
234 * @return This encoder's charset
236 public final Charset charset() {
241 * Returns this encoder's replacement value. </p>
243 * @return This encoder's current replacement,
244 * which is never <tt>null</tt> and is never empty
246 public final byte[] replacement() {
251 * Changes this encoder's replacement value.
253 * <p> This method invokes the {@link #implReplaceWith implReplaceWith}
254 * method, passing the new replacement, after checking that the new
255 * replacement is acceptable. </p>
257 * @param newReplacement
264 * The new replacement; must not be <tt>null</tt>, must have
265 * non-zero length, must not be longer than the value returned by
266 * the {@link #maxBytesPerChar() maxBytesPerChar} method, and
267 * must be {@link #isLegalReplacement </code>legal<code>}
270 * @return This encoder
272 * @throws IllegalArgumentException
273 * If the preconditions on the parameter do not hold
275 public final CharsetEncoder replaceWith(byte[] newReplacement) {
276 if (newReplacement == null)
277 throw new IllegalArgumentException("Null replacement");
278 int len = newReplacement.length;
280 throw new IllegalArgumentException("Empty replacement");
281 if (len > maxBytesPerChar)
282 throw new IllegalArgumentException("Replacement too long");
284 if (!isLegalReplacement(newReplacement))
285 throw new IllegalArgumentException("Illegal replacement");
287 this.replacement = newReplacement;
288 implReplaceWith(newReplacement);
293 * Reports a change to this encoder's replacement value.
295 * <p> The default implementation of this method does nothing. This method
296 * should be overridden by encoders that require notification of changes to
297 * the replacement. </p>
299 * @param newReplacement
301 protected void implReplaceWith(byte[] newReplacement) {
306 private WeakReference<CharsetDecoder> cachedDecoder = null;
309 * Tells whether or not the given byte array is a legal replacement value
312 * <p> A replacement is legal if, and only if, it is a legal sequence of
313 * bytes in this encoder's charset; that is, it must be possible to decode
314 * the replacement into one or more sixteen-bit Unicode characters.
316 * <p> The default implementation of this method is not very efficient; it
317 * should generally be overridden to improve performance. </p>
319 * @param repl The byte array to be tested
321 * @return <tt>true</tt> if, and only if, the given byte array
322 * is a legal replacement value for this encoder
324 public boolean isLegalReplacement(byte[] repl) {
325 WeakReference<CharsetDecoder> wr = cachedDecoder;
326 CharsetDecoder dec = null;
327 if ((wr == null) || ((dec = wr.get()) == null)) {
328 dec = charset().newDecoder();
329 dec.onMalformedInput(CodingErrorAction.REPORT);
330 dec.onUnmappableCharacter(CodingErrorAction.REPORT);
331 cachedDecoder = new WeakReference<CharsetDecoder>(dec);
335 ByteBuffer bb = ByteBuffer.wrap(repl);
336 CharBuffer cb = CharBuffer.allocate((int)(bb.remaining()
337 * dec.maxCharsPerByte()));
338 CoderResult cr = dec.decode(bb, cb, true);
339 return !cr.isError();
345 * Returns this encoder's current action for malformed-input errors. </p>
347 * @return The current malformed-input action, which is never <tt>null</tt>
349 public CodingErrorAction malformedInputAction() {
350 return malformedInputAction;
354 * Changes this encoder's action for malformed-input errors. </p>
356 * <p> This method invokes the {@link #implOnMalformedInput
357 * implOnMalformedInput} method, passing the new action. </p>
359 * @param newAction The new action; must not be <tt>null</tt>
361 * @return This encoder
363 * @throws IllegalArgumentException
364 * If the precondition on the parameter does not hold
366 public final CharsetEncoder onMalformedInput(CodingErrorAction newAction) {
367 if (newAction == null)
368 throw new IllegalArgumentException("Null action");
369 malformedInputAction = newAction;
370 implOnMalformedInput(newAction);
375 * Reports a change to this encoder's malformed-input action.
377 * <p> The default implementation of this method does nothing. This method
378 * should be overridden by encoders that require notification of changes to
379 * the malformed-input action. </p>
381 protected void implOnMalformedInput(CodingErrorAction newAction) { }
384 * Returns this encoder's current action for unmappable-character errors.
387 * @return The current unmappable-character action, which is never
390 public CodingErrorAction unmappableCharacterAction() {
391 return unmappableCharacterAction;
395 * Changes this encoder's action for unmappable-character errors.
397 * <p> This method invokes the {@link #implOnUnmappableCharacter
398 * implOnUnmappableCharacter} method, passing the new action. </p>
400 * @param newAction The new action; must not be <tt>null</tt>
402 * @return This encoder
404 * @throws IllegalArgumentException
405 * If the precondition on the parameter does not hold
407 public final CharsetEncoder onUnmappableCharacter(CodingErrorAction
410 if (newAction == null)
411 throw new IllegalArgumentException("Null action");
412 unmappableCharacterAction = newAction;
413 implOnUnmappableCharacter(newAction);
418 * Reports a change to this encoder's unmappable-character action.
420 * <p> The default implementation of this method does nothing. This method
421 * should be overridden by encoders that require notification of changes to
422 * the unmappable-character action. </p>
424 protected void implOnUnmappableCharacter(CodingErrorAction newAction) { }
427 * Returns the average number of bytes that will be produced for each
428 * character of input. This heuristic value may be used to estimate the size
429 * of the output buffer required for a given input sequence. </p>
431 * @return The average number of bytes produced
432 * per character of input
434 public final float averageBytesPerChar() {
435 return averageBytesPerChar;
439 * Returns the maximum number of bytes that will be produced for each
440 * character of input. This value may be used to compute the worst-case size
441 * of the output buffer required for a given input sequence. </p>
443 * @return The maximum number of bytes that will be produced per
446 public final float maxBytesPerChar() {
447 return maxBytesPerChar;
451 * Encodes as many characters as possible from the given input buffer,
452 * writing the results to the given output buffer.
454 * <p> The buffers are read from, and written to, starting at their current
455 * positions. At most {@link Buffer#remaining in.remaining()} characters
456 * will be read and at most {@link Buffer#remaining out.remaining()}
457 * bytes will be written. The buffers' positions will be advanced to
458 * reflect the characters read and the bytes written, but their marks and
459 * limits will not be modified.
461 * <p> In addition to reading characters from the input buffer and writing
462 * bytes to the output buffer, this method returns a {@link CoderResult}
463 * object to describe its reason for termination:
467 * <li><p> {@link CoderResult#UNDERFLOW} indicates that as much of the
468 * input buffer as possible has been encoded. If there is no further
469 * input then the invoker can proceed to the next step of the
470 * <a href="#steps">encoding operation</a>. Otherwise this method
471 * should be invoked again with further input. </p></li>
473 * <li><p> {@link CoderResult#OVERFLOW} indicates that there is
474 * insufficient space in the output buffer to encode any more characters.
475 * This method should be invoked again with an output buffer that has
476 * more {@linkplain Buffer#remaining remaining} bytes. This is
477 * typically done by draining any encoded bytes from the output
480 * <li><p> A {@link CoderResult#malformedForLength
481 * </code>malformed-input<code>} result indicates that a malformed-input
482 * error has been detected. The malformed characters begin at the input
483 * buffer's (possibly incremented) position; the number of malformed
484 * characters may be determined by invoking the result object's {@link
485 * CoderResult#length() length} method. This case applies only if the
486 * {@link #onMalformedInput </code>malformed action<code>} of this encoder
487 * is {@link CodingErrorAction#REPORT}; otherwise the malformed input
488 * will be ignored or replaced, as requested. </p></li>
490 * <li><p> An {@link CoderResult#unmappableForLength
491 * </code>unmappable-character<code>} result indicates that an
492 * unmappable-character error has been detected. The characters that
493 * encode the unmappable character begin at the input buffer's (possibly
494 * incremented) position; the number of such characters may be determined
495 * by invoking the result object's {@link CoderResult#length() length}
496 * method. This case applies only if the {@link #onUnmappableCharacter
497 * </code>unmappable action<code>} of this encoder is {@link
498 * CodingErrorAction#REPORT}; otherwise the unmappable character will be
499 * ignored or replaced, as requested. </p></li>
503 * In any case, if this method is to be reinvoked in the same encoding
504 * operation then care should be taken to preserve any characters remaining
505 * in the input buffer so that they are available to the next invocation.
507 * <p> The <tt>endOfInput</tt> parameter advises this method as to whether
508 * the invoker can provide further input beyond that contained in the given
509 * input buffer. If there is a possibility of providing additional input
510 * then the invoker should pass <tt>false</tt> for this parameter; if there
511 * is no possibility of providing further input then the invoker should
512 * pass <tt>true</tt>. It is not erroneous, and in fact it is quite
513 * common, to pass <tt>false</tt> in one invocation and later discover that
514 * no further input was actually available. It is critical, however, that
515 * the final invocation of this method in a sequence of invocations always
516 * pass <tt>true</tt> so that any remaining unencoded input will be treated
517 * as being malformed.
519 * <p> This method works by invoking the {@link #encodeLoop encodeLoop}
520 * method, interpreting its results, handling error conditions, and
521 * reinvoking it as necessary. </p>
525 * The input character buffer
528 * The output byte buffer
531 * <tt>true</tt> if, and only if, the invoker can provide no
532 * additional input characters beyond those in the given buffer
534 * @return A coder-result object describing the reason for termination
536 * @throws IllegalStateException
537 * If an encoding operation is already in progress and the previous
538 * step was an invocation neither of the {@link #reset reset}
539 * method, nor of this method with a value of <tt>false</tt> for
540 * the <tt>endOfInput</tt> parameter, nor of this method with a
541 * value of <tt>true</tt> for the <tt>endOfInput</tt> parameter
542 * but a return value indicating an incomplete encoding operation
544 * @throws CoderMalfunctionError
545 * If an invocation of the encodeLoop method threw
546 * an unexpected exception
548 public final CoderResult encode(CharBuffer in, ByteBuffer out,
551 int newState = endOfInput ? ST_END : ST_CODING;
552 if ((state != ST_RESET) && (state != ST_CODING)
553 && !(endOfInput && (state == ST_END)))
554 throwIllegalStateException(state, newState);
561 cr = encodeLoop(in, out);
562 } catch (BufferUnderflowException x) {
563 throw new CoderMalfunctionError(x);
564 } catch (BufferOverflowException x) {
565 throw new CoderMalfunctionError(x);
571 if (cr.isUnderflow()) {
572 if (endOfInput && in.hasRemaining()) {
573 cr = CoderResult.malformedForLength(in.remaining());
574 // Fall through to malformed-input case
580 CodingErrorAction action = null;
581 if (cr.isMalformed())
582 action = malformedInputAction;
583 else if (cr.isUnmappable())
584 action = unmappableCharacterAction;
586 assert false : cr.toString();
588 if (action == CodingErrorAction.REPORT)
591 if (action == CodingErrorAction.REPLACE) {
592 if (out.remaining() < replacement.length)
593 return CoderResult.OVERFLOW;
594 out.put(replacement);
597 if ((action == CodingErrorAction.IGNORE)
598 || (action == CodingErrorAction.REPLACE)) {
599 // Skip erroneous input either way
600 in.position(in.position() + cr.length());
610 * Flushes this encoder.
612 * <p> Some encoders maintain internal state and may need to write some
613 * final bytes to the output buffer once the overall input sequence has
616 * <p> Any additional output is written to the output buffer beginning at
617 * its current position. At most {@link Buffer#remaining out.remaining()}
618 * bytes will be written. The buffer's position will be advanced
619 * appropriately, but its mark and limit will not be modified.
621 * <p> If this method completes successfully then it returns {@link
622 * CoderResult#UNDERFLOW}. If there is insufficient room in the output
623 * buffer then it returns {@link CoderResult#OVERFLOW}. If this happens
624 * then this method must be invoked again, with an output buffer that has
625 * more room, in order to complete the current <a href="#steps">encoding
628 * <p> If this encoder has already been flushed then invoking this method
631 * <p> This method invokes the {@link #implFlush implFlush} method to
632 * perform the actual flushing operation. </p>
635 * The output byte buffer
637 * @return A coder-result object, either {@link CoderResult#UNDERFLOW} or
638 * {@link CoderResult#OVERFLOW}
640 * @throws IllegalStateException
641 * If the previous step of the current encoding operation was an
642 * invocation neither of the {@link #flush flush} method nor of
643 * the three-argument {@link
644 * #encode(CharBuffer,ByteBuffer,boolean) encode} method
645 * with a value of <tt>true</tt> for the <tt>endOfInput</tt>
648 public final CoderResult flush(ByteBuffer out) {
649 if (state == ST_END) {
650 CoderResult cr = implFlush(out);
651 if (cr.isUnderflow())
656 if (state != ST_FLUSHED)
657 throwIllegalStateException(state, ST_FLUSHED);
659 return CoderResult.UNDERFLOW; // Already flushed
663 * Flushes this encoder.
665 * <p> The default implementation of this method does nothing, and always
666 * returns {@link CoderResult#UNDERFLOW}. This method should be overridden
667 * by encoders that may need to write final bytes to the output buffer
668 * once the entire input sequence has been read. </p>
671 * The output byte buffer
673 * @return A coder-result object, either {@link CoderResult#UNDERFLOW} or
674 * {@link CoderResult#OVERFLOW}
676 protected CoderResult implFlush(ByteBuffer out) {
677 return CoderResult.UNDERFLOW;
681 * Resets this encoder, clearing any internal state.
683 * <p> This method resets charset-independent state and also invokes the
684 * {@link #implReset() implReset} method in order to perform any
685 * charset-specific reset actions. </p>
687 * @return This encoder
690 public final CharsetEncoder reset() {
697 * Resets this encoder, clearing any charset-specific internal state.
699 * <p> The default implementation of this method does nothing. This method
700 * should be overridden by encoders that maintain internal state. </p>
702 protected void implReset() { }
705 * Encodes one or more characters into one or more bytes.
707 * <p> This method encapsulates the basic encoding loop, encoding as many
708 * characters as possible until it either runs out of input, runs out of room
709 * in the output buffer, or encounters an encoding error. This method is
710 * invoked by the {@link #encode encode} method, which handles result
711 * interpretation and error recovery.
713 * <p> The buffers are read from, and written to, starting at their current
714 * positions. At most {@link Buffer#remaining in.remaining()} characters
715 * will be read, and at most {@link Buffer#remaining out.remaining()}
716 * bytes will be written. The buffers' positions will be advanced to
717 * reflect the characters read and the bytes written, but their marks and
718 * limits will not be modified.
720 * <p> This method returns a {@link CoderResult} object to describe its
721 * reason for termination, in the same manner as the {@link #encode encode}
722 * method. Most implementations of this method will handle encoding errors
723 * by returning an appropriate result object for interpretation by the
724 * {@link #encode encode} method. An optimized implementation may instead
725 * examine the relevant error action and implement that action itself.
727 * <p> An implementation of this method may perform arbitrary lookahead by
728 * returning {@link CoderResult#UNDERFLOW} until it receives sufficient
732 * The input character buffer
735 * The output byte buffer
737 * @return A coder-result object describing the reason for termination
739 protected abstract CoderResult encodeLoop(CharBuffer in,
743 * Convenience method that encodes the remaining content of a single input
744 * character buffer into a newly-allocated byte buffer.
746 * <p> This method implements an entire <a href="#steps">encoding
747 * operation</a>; that is, it resets this encoder, then it encodes the
748 * characters in the given character buffer, and finally it flushes this
749 * encoder. This method should therefore not be invoked if an encoding
750 * operation is already in progress. </p>
753 * The input character buffer
755 * @return A newly-allocated byte buffer containing the result of the
756 * encoding operation. The buffer's position will be zero and its
757 * limit will follow the last byte written.
759 * @throws IllegalStateException
760 * If an encoding operation is already in progress
762 * @throws MalformedInputException
763 * If the character sequence starting at the input buffer's current
764 * position is not a legal sixteen-bit Unicode sequence and the current malformed-input action
765 * is {@link CodingErrorAction#REPORT}
767 * @throws UnmappableCharacterException
768 * If the character sequence starting at the input buffer's current
769 * position cannot be mapped to an equivalent byte sequence and
770 * the current unmappable-character action is {@link
771 * CodingErrorAction#REPORT}
773 public final ByteBuffer encode(CharBuffer in)
774 throws CharacterCodingException
776 int n = (int)(in.remaining() * averageBytesPerChar());
777 ByteBuffer out = ByteBuffer.allocate(n);
779 if ((n == 0) && (in.remaining() == 0))
783 CoderResult cr = in.hasRemaining() ?
784 encode(in, out, true) : CoderResult.UNDERFLOW;
785 if (cr.isUnderflow())
788 if (cr.isUnderflow())
790 if (cr.isOverflow()) {
791 n = 2*n + 1; // Ensure progress; n might be 0!
792 ByteBuffer o = ByteBuffer.allocate(n);
882 private boolean canEncode(CharBuffer cb) {
883 if (state == ST_FLUSHED)
885 else if (state != ST_RESET)
886 throwIllegalStateException(state, ST_CODING);
887 CodingErrorAction ma = malformedInputAction();
888 CodingErrorAction ua = unmappableCharacterAction();
890 onMalformedInput(CodingErrorAction.REPORT);
891 onUnmappableCharacter(CodingErrorAction.REPORT);
893 } catch (CharacterCodingException x) {
896 onMalformedInput(ma);
897 onUnmappableCharacter(ua);
904 * Tells whether or not this encoder can encode the given character.
906 * <p> This method returns <tt>false</tt> if the given character is a
907 * surrogate character; such characters can be interpreted only when they
908 * are members of a pair consisting of a high surrogate followed by a low
909 * surrogate. The {@link #canEncode(java.lang.CharSequence)
910 * canEncode(CharSequence)} method may be used to test whether or not a
911 * character sequence can be encoded.
913 * <p> This method may modify this encoder's state; it should therefore not
914 * be invoked if an <a href="#steps">encoding operation</a> is already in
917 * <p> The default implementation of this method is not very efficient; it
918 * should generally be overridden to improve performance. </p>
920 * @return <tt>true</tt> if, and only if, this encoder can encode
921 * the given character
923 * @throws IllegalStateException
924 * If an encoding operation is already in progress
926 public boolean canEncode(char c) {
927 CharBuffer cb = CharBuffer.allocate(1);
930 return canEncode(cb);
934 * Tells whether or not this encoder can encode the given character
937 * <p> If this method returns <tt>false</tt> for a particular character
938 * sequence then more information about why the sequence cannot be encoded
939 * may be obtained by performing a full <a href="#steps">encoding
942 * <p> This method may modify this encoder's state; it should therefore not
943 * be invoked if an encoding operation is already in progress.
945 * <p> The default implementation of this method is not very efficient; it
946 * should generally be overridden to improve performance. </p>
948 * @return <tt>true</tt> if, and only if, this encoder can encode
949 * the given character without throwing any exceptions and without
950 * performing any replacements
952 * @throws IllegalStateException
953 * If an encoding operation is already in progress
955 public boolean canEncode(CharSequence cs) {
957 if (cs instanceof CharBuffer)
958 cb = ((CharBuffer)cs).duplicate();
960 cb = CharBuffer.wrap(cs.toString());
961 return canEncode(cb);
967 private void throwIllegalStateException(int from, int to) {
968 throw new IllegalStateException("Current state = " + stateNames[from]
969 + ", new state = " + stateNames[to]);