org.apache.lucene.util
Class AttributeImpl

java.lang.Object
  org.apache.lucene.util.AttributeImpl

All Implemented Interfaces:

Serializable, Cloneable, Attribute

Direct Known Subclasses:

AllowLeadingWildcardAttributeImpl, AnalyzerAttributeImpl, BaseFormAttributeImpl, BaseTokenStreamTestCase.CheckClearAttributesAttributeImpl, BoostAttributeImpl, CategoryAttributeImpl, CharTermAttributeImpl, DateResolutionAttributeImpl, DefaultOperatorAttributeImpl, DefaultPhraseSlopAttributeImpl, FieldBoostMapAttributeImpl, FieldDateResolutionMapAttributeImpl, FlagsAttributeImpl, FuzzyAttributeImpl, InflectionAttributeImpl, KeywordAttributeImpl, LocaleAttributeImpl, LowercaseExpandedTermsAttributeImpl, MultiFieldAttributeImpl, MultiTermRewriteMethodAttributeImpl, OffsetAttributeImpl, PartOfSpeechAttributeImpl, PayloadAttributeImpl, PositionIncrementAttributeImpl, PositionIncrementsAttributeImpl, PositionLengthAttributeImpl, RangeCollatorAttributeImpl, ReadingAttributeImpl, ScriptAttributeImpl, TypeAttributeImpl

public abstract class AttributeImpl
extends Object
implements Cloneable, Serializable, Attribute

Base class for Attributes that can be added to a AttributeSource.

Attributes are used to add data in a dynamic, yet type-safe way to a source of usually streamed objects, e. g. a TokenStream.

See Also:

Serialized Form

Field Summary

protected boolean

enableBackwards Deprecated. this will be removed in Lucene 4.0.

Constructor Summary

AttributeImpl()

Method Summary

abstract void	clear() Clears the values in this AttributeImpl and resets it to its default value.
Object	clone() Shallow clone.
abstract void	copyTo(AttributeImpl target) Copies the values from this Attribute into the passed-in target attribute.
String	reflectAsString(boolean prependAttClass) This method returns the current attribute values as a string in the following format by calling the reflectWith(AttributeReflector) method: iff prependAttClass=true: "AttributeClass#key=value,AttributeClass#key=value" iff prependAttClass=false: "key=value,key=value"
void	reflectWith(AttributeReflector reflector) This method is for introspection of attributes, it should simply add the key/values this attribute holds to the given AttributeReflector.
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

enableBackwards

@Deprecated
protected boolean enableBackwards

Deprecated. this will be removed in Lucene 4.0.

When true (default), if a subclass overrides toString(), its output is parsed by reflectWith(org.apache.lucene.util.AttributeReflector) and used for attribute reflection. This is added to enable attribute implementations from Lucene 2.9 or 3.0 to work correctly with reflection.

Constructor Detail

AttributeImpl

public AttributeImpl()

Method Detail

clear

public abstract void clear()

Clears the values in this AttributeImpl and resets it to its default value. If this implementation implements more than one Attribute interface it clears all.

toString

public String toString()

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object.

WARNING: For backwards compatibility this method is implemented as return reflectAsString(false). In Lucene 4.0 this default implementation will be removed. The reason for this is the problem of CharTermAttributeImpl.toString() that must return a string representation of the term's char sequence.

It is recommeneded to use reflectAsString(boolean) or reflectWith(org.apache.lucene.util.AttributeReflector) to get a well-defined output of AttributeImpl's internals.

Overrides:

toString in class Object

reflectAsString

public final String reflectAsString(boolean prependAttClass)

This method returns the current attribute values as a string in the following format by calling the reflectWith(AttributeReflector) method:

• iff prependAttClass=true: "AttributeClass#key=value,AttributeClass#key=value"
• iff prependAttClass=false: "key=value,key=value"

See Also:

reflectWith(AttributeReflector), toString()

reflectWith

public void reflectWith(AttributeReflector reflector)

This method is for introspection of attributes, it should simply add the key/values this attribute holds to the given AttributeReflector.

The default implementation calls AttributeReflector.reflect(java.lang.Class, java.lang.String, java.lang.Object) for all non-static fields from the implementing class, using the field name as key and the field value as value. The Attribute class is also determined by reflection. Please note that the default implementation can only handle single-Attribute implementations.

Custom implementations look like this (e.g. for a combined attribute implementation):

   public void reflectWith(AttributeReflector reflector) {
     reflector.reflect(CharTermAttribute.class, "term", term());
     reflector.reflect(PositionIncrementAttribute.class, "positionIncrement", getPositionIncrement());
   }
 

If you implement this method, make sure that for each invocation, the same set of Attribute interfaces and keys are passed to AttributeReflector.reflect(java.lang.Class, java.lang.String, java.lang.Object) in the same order, but possibly different values. So don't automatically exclude e.g. null properties!

See Also:

reflectAsString(boolean)

copyTo

public abstract void copyTo(AttributeImpl target)

Copies the values from this Attribute into the passed-in target attribute. The target implementation must support all the Attributes this implementation supports.

clone

public Object clone()

Shallow clone. Subclasses must override this if they need to clone any members deeply,

Overrides:

clone in class Object