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 encoding operation:
Reset the encoder via the reset method, unless it
has not been used before;
Invoke the encode method zero or more times, as
long as additional input may be available, passing false for the
endOfInput argument and filling the input buffer and flushing the
output buffer between invocations;
Invoke the encode method one final time, passing
true for the endOfInput argument; and then
Invoke the flush method so that the encoder can
flush any internal state to the output buffer.
encode method will encode as many
characters as possible from the input buffer, writing the resulting bytes
to the output buffer. The 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 CoderResult 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 malformed. If
the input character sequence is legal but cannot be mapped to a valid
byte sequence in the given charset then an unmappable character has been encountered.
How an encoding error is handled depends upon the action requested for
that type of error, which is described by an instance of the The default action for malformed-input and unmappable-character errors
is to 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 Instances of this class are not safe for use by multiple concurrent
threads. CodingErrorActionCodingErrorAction.IGNORECodingErrorAction.REPORTCoderResult replace 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 { (byte)'?' };
its value may be changed via the replaceWith method.
report them. The
malformed-input error action may be changed via the onMalformedInput(java.nio.charset.CodingErrorAction)onUnmappableCharacter(java.nio.charset.CodingErrorAction)encodeLoop method, which
encapsulates the basic encoding loop. A subclass that maintains internal
state should, additionally, override the implFlush and
implReset methods.
java.nio.ByteBufferjava.nio.CharBufferCharsetCharsetDecoder
averageBytesPerChar
A positive float value indicating the expected number of
bytes that will be produced for each input charactermaxBytesPerChar
A positive float value indicating the maximum number of
bytes that will be produced for each input characterreplacement
The initial replacement; must not be null, must have
non-zero length, must not be longer than maxBytesPerChar,
and must be java.lang.IllegalArgumentException
If the preconditions on the parameters do not holdaverageBytesPerChar
A positive float value indicating the expected number of
bytes that will be produced for each input charactermaxBytesPerChar
A positive float value indicating the maximum number of
bytes that will be produced for each input characterjava.lang.IllegalArgumentException
If the preconditions on the parameters do not hold This method invokes the implReplaceWith
method, passing the new replacement, after checking that the new
replacement is acceptable.
newReplacement
The new replacement; must not be null, must have
non-zero length, must not be longer than the value returned by
the maxBytesPerChar method, and
must be java.lang.IllegalArgumentException
If the preconditions on the parameter do not holdA 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.
The default implementation of this method is not very efficient; it should generally be overridden to improve performance.
repl The byte array to be tested This method invokes the implOnMalformedInput method, passing the new action.
newAction The new action; must not be nulljava.lang.IllegalArgumentException
If the precondition on the parameter does not hold This method invokes the implOnUnmappableCharacter method, passing the new action.
newAction The new action; must not be nulljava.lang.IllegalArgumentException
If the precondition on the parameter does not hold The buffers are read from, and written to, starting at their current
positions. At most in.remaining() characters
will be read and at most 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.
In addition to reading characters from the input buffer and writing
bytes to the output buffer, this method returns a CoderResult
CoderResult.UNDERFLOW
CoderResult.OVERFLOW
A malformed-input 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 CoderResult.length()malformed action of this encoder
is CodingErrorAction.REPORT
An unmappable-character 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 length
method. This case applies only if the unmappable action of this encoder is CodingErrorAction.REPORT
The endOfInput 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 false for this parameter; if there is no possibility of providing further input then the invoker should pass true. It is not erroneous, and in fact it is quite common, to pass false 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 true so that any remaining unencoded input will be treated as being malformed.
This method works by invoking the encodeLoop
method, interpreting its results, handling error conditions, and
reinvoking it as necessary.
in
The input character bufferout
The output byte bufferendOfInput
true if, and only if, the invoker can provide no
additional input characters beyond those in the given bufferjava.lang.IllegalStateException
If an encoding operation is already in progress and the previous
step was an invocation neither of the reset
method, nor of this method with a value of false for
the endOfInput parameter, nor of this method with a
value of true for the endOfInput parameter
but a return value indicating an incomplete encoding operationCoderMalfunctionError
If an invocation of the encodeLoop method threw
an unexpected exceptionSome encoders maintain internal state and may need to write some final bytes to the output buffer once the overall input sequence has been read.
Any additional output is written to the output buffer beginning at
its current position. At most out.remaining()
bytes will be written. The buffer's position will be advanced
appropriately, but its mark and limit will not be modified.
If this method completes successfully then it returns CoderResult.UNDERFLOWCoderResult.OVERFLOW
If this encoder has already been flushed then invoking this method has no effect.
This method invokes the implFlush method to
perform the actual flushing operation.
out
The output byte bufferCoderResult.UNDERFLOWCoderResult.OVERFLOWjava.lang.IllegalStateException
If the previous step of the current encoding operation was an
invocation neither of the flush method nor of
the three-argument encode(java.nio.CharBuffer,java.nio.ByteBuffer,boolean) The default implementation of this method does nothing, and always
returns CoderResult.UNDERFLOW
out
The output byte bufferCoderResult.UNDERFLOWCoderResult.OVERFLOW 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 encode method, which handles result
interpretation and error recovery.
The buffers are read from, and written to, starting at their current
positions. At most in.remaining() characters
will be read, and at most 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.
This method returns a CoderResultencode
method. Most implementations of this method will handle encoding errors
by returning an appropriate result object for interpretation by the
encode method. An optimized implementation may instead
examine the relevant error action and implement that action itself.
An implementation of this method may perform arbitrary lookahead by
returning CoderResult.UNDERFLOW
in
The input character bufferout
The output byte bufferThis method implements an entire encoding operation; 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.
in
The input character bufferjava.lang.IllegalStateException
If an encoding operation is already in progressMalformedInputException
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 CodingErrorAction.REPORTUnmappableCharacterException
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 CodingErrorAction.REPORT This method returns false 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 canEncode(CharSequence) method may be used to test whether or not a
character sequence can be encoded.
This method may modify this encoder's state; it should therefore not be invoked if an encoding operation is already in progress.
The default implementation of this method is not very efficient; it should generally be overridden to improve performance.
java.lang.IllegalStateException
If an encoding operation is already in progressIf this method returns false for a particular character sequence then more information about why the sequence cannot be encoded may be obtained by performing a full encoding operation.
This method may modify this encoder's state; it should therefore not be invoked if an encoding operation is already in progress.
The default implementation of this method is not very efficient; it should generally be overridden to improve performance.
java.lang.IllegalStateException
If an encoding operation is already in progress