com.persistit.encoding

Interface KeyDisplayer

All Superinterfaces:

KeyCoder

public interface KeyDisplayer
extends KeyCoder

An extension of KeyCoder that adds the displayKeySegment(com.persistit.Key, java.lang.Appendable, java.lang.Class<?>, com.persistit.encoding.CoderContext) method. This method populates a supplied Appendable with a displayable, human-readable representation of the Object value that was formerly written to a Key by this KeyDisplayer.

The toString method and decodeDisplayable methods of Value preferentially use the registered KeyDisplayer, if present, to generate a String representation of an object value encoded in a Key.

Version:

1.0

Method Summary

Modifier and Type	Method and Description
void	displayKeySegment(Key key, Appendable target, Class<?> clazz, CoderContext context) Populates the state of the supplied target Object by decoding the next key segment of the supplied Key.

Methods inherited from interface com.persistit.encoding.KeyCoder

appendKeySegment, decodeKeySegment, isZeroByteFree

Method Detail

displayKeySegment

void displayKeySegment(Key key,
                       Appendable target,
                       Class<?> clazz,
                       CoderContext context)
                throws ConversionException

Populates the state of the supplied target Object by decoding the next key segment of the supplied Key. This method will be called only if this KeyRenderer has been registered with the current CoderManager to encode objects having the supplied Class value. In addition, Persistit will never call this method to decode a value that was null when written because null values are handled by built-in encoding logic.

When this method is called the value Key.getIndex() will be the offset within the key of the first encoded byte. The key segment is zero-byte terminated.

Parameters:

key - The Key from which interior fields of the object are to be retrieved

target - An @{link Appendable} object into which the key segment is to be written

clazz - The class of the object that was originally encoded into Value.

context - An arbitrary object that can optionally be supplied by the application to convey an application-specific context for the operation. (See CoderContext.) The default value is null.

Throws:

ConversionException