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  * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

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 // -- 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 sixteen-bit Unicode characters into a sequence of

  * bytes in a specific charset.

  *

  * <a name="steps">

  *

  * <p> The input character sequence is provided in a character buffer or a series

  * of such buffers.  The output byte sequence is written to a byte buffer

  * or a series of such buffers.  An encoder should always be used by making

  * the following sequence of method invocations, hereinafter referred to as an

  * <i>encoding operation</i>:

  *

  * <ol>

  *

  *   <li><p> Reset the encoder via the {@link #reset reset} method, unless it

  *   has not been used before; </p></li>

  *

  *   <li><p> Invoke the {@link #encode encode} 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 #encode encode} 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 encoder can

  *   flush any internal state to the output buffer. </p></li>

  *

  * </ol>

  *

  * Each invocation of the {@link #encode encode} method will encode as many

  * characters as possible from the input buffer, writing the resulting bytes

  * to the output buffer.  The {@link #encode encode} method returns when more

  * input is required, when there is not enough room in the output buffer, or

  * when an encoding 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 an encoding error, as appropriate, and try again.

  *

  * <a name="ce">

  *

  * <p> There are two general types of encoding errors.  If the input character

  * sequence is not a legal sixteen-bit Unicode sequence then the input is considered <i>malformed</i>.  If

  * the input character sequence is legal but cannot be mapped to a valid

  * byte sequence in the given charset then an <i>unmappable character</i> has been encountered.

  *

  * <a name="cae">

  *

  * <p> How an encoding 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 byte array.  The replacement

  *

  * is initially set to the encoder's default replacement, which often

  * (but not always) has the initial value&nbsp;<tt>{</tt>&nbsp;<tt>(byte)'?'</tt>&nbsp;<tt>}</tt>;

  *

  * its value may be changed via the {@link #replaceWith(byte[])

  * 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 encoding

  * process, including the implementation of error actions.  An encoder for a

  * specific charset, which is a concrete subclass of this class, need only

  * implement the abstract {@link #encodeLoop encodeLoop} method, which

  * encapsulates the basic encoding 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 CharsetDecoder

  */

 public abstract class CharsetEncoder {

     private final Charset charset;

     private final float averageBytesPerChar;

     private final float maxBytesPerChar;

     private byte[] 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 encoder.  The new encoder will have the given

      * bytes-per-char and replacement values. </p>

      *

      * @param  averageBytesPerChar

      *         A positive float value indicating the expected number of

      *         bytes that will be produced for each input character

      *

      * @param  maxBytesPerChar

      *         A positive float value indicating the maximum number of

      *         bytes that will be produced for each input character

      *

      * @param  replacement

      *         The initial replacement; must not be <tt>null</tt>, must have

      *         non-zero length, must not be longer than maxBytesPerChar,

      *         and must be {@link #isLegalReplacement </code>legal<code>}

      *

      * @throws  IllegalArgumentException

      *          If the preconditions on the parameters do not hold

      */

     protected

     CharsetEncoder(Charset cs,

                    float averageBytesPerChar,

                    float maxBytesPerChar,

                    byte[] replacement)

     {

         this.charset = cs;

         if (averageBytesPerChar <= 0.0f)

             throw new IllegalArgumentException("Non-positive "

                                                + "averageBytesPerChar");

         if (maxBytesPerChar <= 0.0f)

             throw new IllegalArgumentException("Non-positive "

                                                + "maxBytesPerChar");

         if (!Charset.atBugLevel("1.4")) {

             if (averageBytesPerChar > maxBytesPerChar)

                 throw new IllegalArgumentException("averageBytesPerChar"

                                                    + " exceeds "

                                                    + "maxBytesPerChar");

         }

         this.replacement = replacement;

         this.averageBytesPerChar = averageBytesPerChar;

         this.maxBytesPerChar = maxBytesPerChar;

         replaceWith(replacement);

     }

     /**

      * Initializes a new encoder.  The new encoder will have the given

      * bytes-per-char values and its replacement will be the

      * byte array <tt>{</tt>&nbsp;<tt>(byte)'?'</tt>&nbsp;<tt>}</tt>. </p>

      *

      * @param  averageBytesPerChar

      *         A positive float value indicating the expected number of

      *         bytes that will be produced for each input character

      *

      * @param  maxBytesPerChar

      *         A positive float value indicating the maximum number of

      *         bytes that will be produced for each input character

      *

      * @throws  IllegalArgumentException

      *          If the preconditions on the parameters do not hold

      */

     protected CharsetEncoder(Charset cs,

                              float averageBytesPerChar,

                              float maxBytesPerChar)

     {

         this(cs,

              averageBytesPerChar, maxBytesPerChar,

              new byte[] { (byte)'?' });

     }

     /**

      * Returns the charset that created this encoder.  </p>

      *

      * @return  This encoder's charset

      */

     public final Charset charset() {

         return charset;

     }

     /**

      * Returns this encoder's replacement value. </p>

      *

      * @return  This encoder's current replacement,

      *          which is never <tt>null</tt> and is never empty

      */

     public final byte[] replacement() {

         return replacement;

     }

     /**

      * Changes this encoder'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>, must have

      *         non-zero length, must not be longer than the value returned by

      *         the {@link #maxBytesPerChar() maxBytesPerChar} method, and

      *         must be {@link #isLegalReplacement </code>legal<code>}

      *

      * @return  This encoder

      *

      * @throws  IllegalArgumentException

      *          If the preconditions on the parameter do not hold

      */

     public final CharsetEncoder replaceWith(byte[] newReplacement) {

         if (newReplacement == null)

             throw new IllegalArgumentException("Null replacement");

         int len = newReplacement.length;

         if (len == 0)

             throw new IllegalArgumentException("Empty replacement");

         if (len > maxBytesPerChar)

             throw new IllegalArgumentException("Replacement too long");

         if (!isLegalReplacement(newReplacement))

             throw new IllegalArgumentException("Illegal replacement");

         this.replacement = newReplacement;

         implReplaceWith(newReplacement);

         return this;

     }

     /**

      * Reports a change to this encoder's replacement value.

      *

      * <p> The default implementation of this method does nothing.  This method

      * should be overridden by encoders that require notification of changes to

      * the replacement.  </p>

      *

      * @param  newReplacement

      */

     protected void implReplaceWith(byte[] newReplacement) {

     }

     private WeakReference<CharsetDecoder> cachedDecoder = null;

     /**

      * Tells whether or not the given byte array is a legal replacement value

      * for this encoder.

      *

      * <p> A replacement is legal if, and only if, it is a legal sequence of

      * bytes in this encoder's charset; that is, it must be possible to decode

      * the replacement into one or more sixteen-bit Unicode characters.

      *

      * <p> The default implementation of this method is not very efficient; it

      * should generally be overridden to improve performance.  </p>

      *

      * @param  repl  The byte array to be tested

      *

      * @return  <tt>true</tt> if, and only if, the given byte array

      *          is a legal replacement value for this encoder

      */

     public boolean isLegalReplacement(byte[] repl) {

         WeakReference<CharsetDecoder> wr = cachedDecoder;

         CharsetDecoder dec = null;

         if ((wr == null) || ((dec = wr.get()) == null)) {

             dec = charset().newDecoder();

             dec.onMalformedInput(CodingErrorAction.REPORT);

             dec.onUnmappableCharacter(CodingErrorAction.REPORT);

             cachedDecoder = new WeakReference<CharsetDecoder>(dec);

         } else {

             dec.reset();

         }

         ByteBuffer bb = ByteBuffer.wrap(repl);

         CharBuffer cb = CharBuffer.allocate((int)(bb.remaining()

                                                   * dec.maxCharsPerByte()));

         CoderResult cr = dec.decode(bb, cb, true);

         return !cr.isError();

     }

     /**

      * Returns this encoder'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 encoder'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 encoder

      *

      * @throws IllegalArgumentException

      *         If the precondition on the parameter does not hold

      */

     public final CharsetEncoder onMalformedInput(CodingErrorAction newAction) {

         if (newAction == null)

             throw new IllegalArgumentException("Null action");

         malformedInputAction = newAction;

         implOnMalformedInput(newAction);

         return this;

     }

     /**

      * Reports a change to this encoder's malformed-input action.

      *

      * <p> The default implementation of this method does nothing.  This method

      * should be overridden by encoders that require notification of changes to

      * the malformed-input action.  </p>

      */

     protected void implOnMalformedInput(CodingErrorAction newAction) { }

     /**

      * Returns this encoder'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 encoder'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 encoder

      *

      * @throws IllegalArgumentException

      *         If the precondition on the parameter does not hold

      */

     public final CharsetEncoder onUnmappableCharacter(CodingErrorAction

                                                       newAction)

     {

         if (newAction == null)

             throw new IllegalArgumentException("Null action");

         unmappableCharacterAction = newAction;

         implOnUnmappableCharacter(newAction);

         return this;

     }

     /**

      * Reports a change to this encoder's unmappable-character action.

      *

      * <p> The default implementation of this method does nothing.  This method

      * should be overridden by encoders that require notification of changes to

      * the unmappable-character action.  </p>

      */

     protected void implOnUnmappableCharacter(CodingErrorAction newAction) { }

     /**

      * Returns the average number of bytes that will be produced for each

      * character 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 bytes produced

      *          per character of input

      */

     public final float averageBytesPerChar() {

         return averageBytesPerChar;

     }

     /**

      * Returns the maximum number of bytes that will be produced for each

      * character 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 bytes that will be produced per

      *          character of input

      */

     public final float maxBytesPerChar() {

         return maxBytesPerChar;

     }

     /**

      * Encodes as many characters 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()} characters

      * will be read and at most {@link Buffer#remaining out.remaining()}

      * bytes will be written.  The buffers' positions will be advanced to

      * reflect the characters read and the bytes written, but their marks and

      * limits will not be modified.

      *

      * <p> In addition to reading characters from the input buffer and writing

      * bytes 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 encoded.  If there is no further

      *   input then the invoker can proceed to the next step of the

      *   <a href="#steps">encoding 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 encode any more characters.

      *   This method should be invoked again with an output buffer that has

      *   more {@linkplain Buffer#remaining remaining} bytes. This is

      *   typically done by draining any encoded bytes 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 characters begin at the input

      *   buffer's (possibly incremented) position; the number of malformed

      *   characters 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 encoder

      *   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 characters that

      *   encode the unmappable character begin at the input buffer's (possibly

      *   incremented) position; the number of such characters 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 encoder 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 encoding

      * operation then care should be taken to preserve any characters 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 unencoded input will be treated

      * as being malformed.

      *

      * <p> This method works by invoking the {@link #encodeLoop encodeLoop}

      * method, interpreting its results, handling error conditions, and

      * reinvoking it as necessary.  </p>

      *

      *

      * @param  in

      *         The input character buffer

      *

      * @param  out

      *         The output byte buffer

      *

      * @param  endOfInput

      *         <tt>true</tt> if, and only if, the invoker can provide no

      *         additional input characters beyond those in the given buffer

      *

      * @return  A coder-result object describing the reason for termination

      *

      * @throws  IllegalStateException

      *          If an encoding 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 encoding operation

      *

      * @throws  CoderMalfunctionError

      *          If an invocation of the encodeLoop method threw

      *          an unexpected exception

      */

     public final CoderResult encode(CharBuffer in, ByteBuffer 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 = encodeLoop(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 encoder.

      *

      * <p> Some encoders maintain internal state and may need to write some

      * final bytes 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()}

      * bytes 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">encoding

      * operation</a>.

      *

      * <p> If this encoder 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 byte buffer

      *

      * @return  A coder-result object, either {@link CoderResult#UNDERFLOW} or

      *          {@link CoderResult#OVERFLOW}

      *

      * @throws  IllegalStateException

      *          If the previous step of the current encoding operation was an

      *          invocation neither of the {@link #flush flush} method nor of

      *          the three-argument {@link

      *          #encode(CharBuffer,ByteBuffer,boolean) encode} method

      *          with a value of <tt>true</tt> for the <tt>endOfInput</tt>

      *          parameter

      */

     public final CoderResult flush(ByteBuffer 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 encoder.

      *

      * <p> The default implementation of this method does nothing, and always

      * returns {@link CoderResult#UNDERFLOW}.  This method should be overridden

      * by encoders that may need to write final bytes to the output buffer

      * once the entire input sequence has been read. </p>

      *

      * @param  out

      *         The output byte buffer

      *

      * @return  A coder-result object, either {@link CoderResult#UNDERFLOW} or

      *          {@link CoderResult#OVERFLOW}

      */

     protected CoderResult implFlush(ByteBuffer out) {

         return CoderResult.UNDERFLOW;

     }

     /**

      * Resets this encoder, 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 encoder

      *

      */

     public final CharsetEncoder reset() {

         implReset();

         state = ST_RESET;

         return this;

     }

     /**

      * Resets this encoder, clearing any charset-specific internal state.

      *

      * <p> The default implementation of this method does nothing.  This method

      * should be overridden by encoders that maintain internal state.  </p>

      */

     protected void implReset() { }

     /**

      * Encodes one or more characters into one or more bytes.

      *

      * <p> This method encapsulates the basic encoding loop, encoding as many

      * characters as possible until it either runs out of input, runs out of room

      * in the output buffer, or encounters an encoding error.  This method is

      * invoked by the {@link #encode encode} 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()} characters

      * will be read, and at most {@link Buffer#remaining out.remaining()}

      * bytes will be written.  The buffers' positions will be advanced to

      * reflect the characters read and the bytes 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 #encode encode}

      * method.  Most implementations of this method will handle encoding errors

      * by returning an appropriate result object for interpretation by the

      * {@link #encode encode} 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 character buffer

      *

      * @param  out

      *         The output byte buffer

      *

      * @return  A coder-result object describing the reason for termination

      */

     protected abstract CoderResult encodeLoop(CharBuffer in,

                                               ByteBuffer out);

     /**

      * Convenience method that encodes the remaining content of a single input

      * character buffer into a newly-allocated byte buffer.

      *

      * <p> This method implements an entire <a href="#steps">encoding

      * operation</a>; that is, it resets this encoder, then it encodes the

      * characters in the given character buffer, and finally it flushes this

      * encoder.  This method should therefore not be invoked if an encoding

      * operation is already in progress.  </p>

      *

      * @param  in

      *         The input character buffer

      *

      * @return A newly-allocated byte buffer containing the result of the

      *         encoding operation.  The buffer's position will be zero and its

      *         limit will follow the last byte written.

      *

      * @throws  IllegalStateException

      *          If an encoding operation is already in progress

      *

      * @throws  MalformedInputException

      *          If the character sequence starting at the input buffer's current

      *          position is not a legal sixteen-bit Unicode sequence and the current malformed-input action

      *          is {@link CodingErrorAction#REPORT}

      *

      * @throws  UnmappableCharacterException

      *          If the character sequence starting at the input buffer's current

      *          position cannot be mapped to an equivalent byte sequence and

      *          the current unmappable-character action is {@link

      *          CodingErrorAction#REPORT}

      */

     public final ByteBuffer encode(CharBuffer in)

         throws CharacterCodingException

     {

         int n = (int)(in.remaining() * averageBytesPerChar());

         ByteBuffer out = ByteBuffer.allocate(n);

         if ((n == 0) && (in.remaining() == 0))

             return out;

         reset();

         for (;;) {

             CoderResult cr = in.hasRemaining() ?

                 encode(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!

                 ByteBuffer o = ByteBuffer.allocate(n);

                 out.flip();

                 o.put(out);

                 out = o;

                 continue;

             }

             cr.throwException();

         }

         out.flip();

         return out;

     }

     private boolean canEncode(CharBuffer cb) {

         if (state == ST_FLUSHED)

             reset();

         else if (state != ST_RESET)

             throwIllegalStateException(state, ST_CODING);

         CodingErrorAction ma = malformedInputAction();

         CodingErrorAction ua = unmappableCharacterAction();

         try {

             onMalformedInput(CodingErrorAction.REPORT);

             onUnmappableCharacter(CodingErrorAction.REPORT);

             encode(cb);

         } catch (CharacterCodingException x) {

             return false;

         } finally {

             onMalformedInput(ma);

             onUnmappableCharacter(ua);

             reset();

         }

         return true;

     }

     /**

      * Tells whether or not this encoder can encode the given character.

      *

      * <p> This method returns <tt>false</tt> if the given character is a

      * surrogate character; such characters can be interpreted only when they

      * are members of a pair consisting of a high surrogate followed by a low

      * surrogate.  The {@link #canEncode(java.lang.CharSequence)

      * canEncode(CharSequence)} method may be used to test whether or not a

      * character sequence can be encoded.

      *

      * <p> This method may modify this encoder's state; it should therefore not

      * be invoked if an <a href="#steps">encoding operation</a> is already in

      * progress.

      *

      * <p> The default implementation of this method is not very efficient; it

      * should generally be overridden to improve performance.  </p>

      *

      * @return  <tt>true</tt> if, and only if, this encoder can encode

      *          the given character

      *

      * @throws  IllegalStateException

      *          If an encoding operation is already in progress

      */

     public boolean canEncode(char c) {

         CharBuffer cb = CharBuffer.allocate(1);

         cb.put(c);

         cb.flip();

         return canEncode(cb);

     }

     /**

      * Tells whether or not this encoder can encode the given character

      * sequence.

      *

      * <p> If this method returns <tt>false</tt> for a particular character

      * sequence then more information about why the sequence cannot be encoded

      * may be obtained by performing a full <a href="#steps">encoding

      * operation</a>.

      *

      * <p> This method may modify this encoder's state; it should therefore not

      * be invoked if an encoding operation is already in progress.

      *

      * <p> The default implementation of this method is not very efficient; it

      * should generally be overridden to improve performance.  </p>

      *

      * @return  <tt>true</tt> if, and only if, this encoder can encode

      *          the given character without throwing any exceptions and without

      *          performing any replacements

      *

      * @throws  IllegalStateException

      *          If an encoding operation is already in progress

      */

     public boolean canEncode(CharSequence cs) {

         CharBuffer cb;

         if (cs instanceof CharBuffer)

             cb = ((CharBuffer)cs).duplicate();

         else

             cb = CharBuffer.wrap(cs.toString());

         return canEncode(cb);

     }

     private void throwIllegalStateException(int from, int to) {

         throw new IllegalStateException("Current state = " + stateNames[from]

                                         + ", new state = " + stateNames[to]);

     }

 }