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There are two general types of $coding$ errors. If the input $itype$ sequence is $notLegal$ then the input is considered malformed. If the input $itype$ sequence is legal but cannot be mapped to a valid $outSequence$ then an unmappable character has been encountered.

How $a$ $coding$ error is handled depends upon the action requested for that type of error, which is described by an instance of the CodingErrorAction class. The possible error actions are to CodingErrorAction.IGNORE ignore the erroneous input, CodingErrorAction.REPORT report the error to the invoker via the returned CoderResult object, or CodingErrorAction.REPLACEreplace the erroneous input with the current value of the replacement $replTypeName$. The replacement #if[encoder] is initially set to the $coder$'s default replacement, which often (but not always) has the initial value $defaultReplName$; #end[encoder] #if[decoder] has the initial value $defaultReplName$; #end[decoder] its value may be changed via the Charset$Coder$.replaceWith($replFQType$)replaceWith method.

The default action for malformed-input and unmappable-character errors is to CodingErrorAction.REPORT report them. The malformed-input error action may be changed via the Charset$Coder$.onMalformedInput(CodingErrorAction) onMalformedInput method; the unmappable-character action may be changed via the Charset$Coder$.onUnmappableCharacter(CodingErrorAction) onUnmappableCharacter method.

This class is designed to handle many of the details of the $coding$ process, including the implementation of error actions. $A$ $coder$ for a specific charset, which is a concrete subclass of this class, need only implement the abstract Charset$Coder$.$code$Loop $code$Loop method, which encapsulates the basic $coding$ loop. A subclass that maintains internal state should, additionally, override the Charset$Coder$.implFlush implFlush and Charset$Coder$.implReset implReset methods.

Instances of this class are not safe for use by multiple concurrent threads.

The buffers are read from, and written to, starting at their current positions.

This method implements an entire $coding$ operation; that is, it resets this $coder$, then it $code$s the $itype$s in the given $itype$ buffer, and finally it flushes this $coder$.

This method encapsulates the basic $coding$ loop, $coding$ as many $itype$s as possible until it either runs out of input, runs out of room in the output buffer, or encounters $a$ $coding$ error.

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.

If 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.

If this decoder implements an auto-detecting charset then this method returns the actual charset once it has been detected.

Some $coder$s maintain internal state and may need to write some final $otype$s 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.

The default implementation of this method does nothing, and always returns CoderResult.UNDERFLOW .

The default implementation of this method does nothing.

The default implementation of this method does nothing.

The default implementation of this method does nothing.

The default implementation of this method does nothing.

The default implementation of this method always returns false; it should be overridden by auto-detecting decoders to return true.

If this decoder implements an auto-detecting charset then at a single point during a decoding operation this method may start returning true to indicate that a specific charset has been detected in the input byte sequence.

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.

The default implementation of this method is not very efficient; it should generally be overridden to improve performance.

This method invokes the Charset$Coder$.implOnUnmappableCharacterimplOnUnmappableCharacter method, passing the new action.

This method invokes the Charset$Coder$.implReplaceWith implReplaceWith method, passing the new replacement, after checking that the new replacement is acceptable.

This method resets charset-independent state and also invokes the Charset$Coder$.implReset() implReset method in order to perform any charset-specific reset actions.

The buffers are read from, and written to, starting at their current positions. At most Buffer.remaining in.remaining() $itype$s will be read and at most Buffer.remaining out.remaining() $otype$s will be written. The buffers' positions will be advanced to reflect the $itype$s read and the $otype$s written, but their marks and limits will not be modified.

In addition to reading $itype$s from the input buffer and writing $otype$s to the output buffer, this method returns a CoderResult object to describe its reason for termination:

• CoderResult.UNDERFLOW indicates that as much of the input buffer as possible has been $code$d. If there is no further input then the invoker can proceed to the next step of the $coding$ operation. Otherwise this method should be invoked again with further input.

• CoderResult.OVERFLOW indicates that there is insufficient space in the output buffer to $code$ any more $itype$s. This method should be invoked again with an output buffer that has more $otype$s. This is typically done by draining any $code$d $otype$s from the output buffer.

• A CoderResult.malformedForLengthmalformed-input result indicates that a malformed-input error has been detected. The malformed $itype$s begin at the input buffer's (possibly incremented) position; the number of malformed $itype$s may be determined by invoking the result object's CoderResult.length length method. This case applies only if the Charset$Coder$.onMalformedInput malformed action of this $coder$ is CodingErrorAction.REPORT ; otherwise the malformed input will be ignored or replaced, as requested.

• An CoderResult.unmappableForLengthunmappable-character result indicates that an unmappable-character error has been detected. The $itype$s that $code$ the unmappable character begin at the input buffer's (possibly incremented) position; the number of such $itype$s may be determined by invoking the result object's CoderResult.length length method. This case applies only if the Charset$Coder$.onUnmappableCharacterunmappable action of this $coder$ is CodingErrorAction.REPORT ; otherwise the unmappable character will be ignored or replaced, as requested.

This method implements an entire $coding$ operation; that is, it resets this $coder$, then it $code$s the $itype$s in the given $itype$ buffer, and finally it flushes this $coder$. This method should therefore not be invoked if $a$ $coding$ operation is already in progress.

This method encapsulates the basic $coding$ loop, $coding$ as many $itype$s as possible until it either runs out of input, runs out of room in the output buffer, or encounters $a$ $coding$ error. This method is invoked by the Charset$Coder$.$code$ $code$ method, which handles result interpretation and error recovery.

The buffers are read from, and written to, starting at their current positions. At most Buffer.remaining in.remaining() $itype$s will be read, and at most Buffer.remaining out.remaining() $otype$s will be written. The buffers' positions will be advanced to reflect the $itype$s read and the $otype$s written, but their marks and limits will not be modified.

This method returns a CoderResult object to describe its reason for termination, in the same manner as the Charset$Coder$.$code$ $code$ method. Most implementations of this method will handle $coding$ errors by returning an appropriate result object for interpretation by the Charset$Coder$.$code$ $code$ 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 until it receives sufficient input.

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 Charset$Coder$.canEncode(java.lang.CharSequence)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.

If 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.

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 IllegalStateException .

The default implementation of this method always throws an UnsupportedOperationException ; it should be overridden by auto-detecting decoders to return the appropriate value.

Some $coder$s maintain internal state and may need to write some final $otype$s 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 Buffer.remaining out.remaining() $otype$s 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.UNDERFLOW . If there is insufficient room in the output buffer then it returns 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 $coding$ operation.

If this $coder$ has already been flushed then invoking this method has no effect.

This method invokes the Charset$Coder$.implFlush implFlush method to perform the actual flushing operation.

The default implementation of this method does nothing, and always returns CoderResult.UNDERFLOW . This method should be overridden by $coder$s that may need to write final $otype$s to the output buffer once the entire input sequence has been read.

The default implementation of this method does nothing. This method should be overridden by $coder$s that require notification of changes to the malformed-input action.

The default implementation of this method does nothing. This method should be overridden by $coder$s that require notification of changes to the unmappable-character action.

The default implementation of this method does nothing. This method should be overridden by $coder$s that require notification of changes to the replacement.

The default implementation of this method does nothing. This method should be overridden by $coder$s that maintain internal state.

The default implementation of this method always returns false; it should be overridden by auto-detecting decoders to return true.

If this decoder implements an auto-detecting charset then at a single point during a decoding operation this method may start returning true to indicate that a specific charset has been detected in the input byte sequence. Once this occurs, the Charset$Coder$.detectedCharsetdetectedCharset method may be invoked to retrieve the detected charset.

That this method returns false 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.

The default implementation of this method always throws an UnsupportedOperationException ; it should be overridden by auto-detecting decoders to return true once the input charset has been determined.

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.

The default implementation of this method is not very efficient; it should generally be overridden to improve performance.

This method invokes the Charset$Coder$.implOnMalformedInputimplOnMalformedInput method, passing the new action.

This method invokes the Charset$Coder$.implOnUnmappableCharacterimplOnUnmappableCharacter method, passing the new action.

This method invokes the Charset$Coder$.implReplaceWith implReplaceWith method, passing the new replacement, after checking that the new replacement is acceptable.

This method resets charset-independent state and also invokes the Charset$Coder$.implReset() implReset method in order to perform any charset-specific reset actions.