org.apache.lucene.util

Class AttributeImpl

java.lang.Object

org.apache.lucene.util.AttributeImpl

All Implemented Interfaces:

Cloneable, Attribute

Direct Known Subclasses:

BoostAttributeImpl, BytesTermAttributeImpl, CharTermAttributeImpl, FlagsAttributeImpl, FuzzyTermsEnum.LevenshteinAutomataAttributeImpl, KeywordAttributeImpl, MaxNonCompetitiveBoostAttributeImpl, NumericTokenStream.NumericTermAttributeImpl, OffsetAttributeImpl, PayloadAttributeImpl, PositionIncrementAttributeImpl, PositionLengthAttributeImpl, TypeAttributeImpl

public abstract class AttributeImpl
extends Object
implements Cloneable, 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.

Constructor Summary

Constructors

Constructor and Description
AttributeImpl()

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	clear() Clears the values in this AttributeImpl and resets it to its default value.
AttributeImpl	clone() In most cases the clone is, and should be, deep in order to be able to properly capture the state of all attributes.
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.

Methods inherited from class java.lang.Object

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

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.

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)

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.

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<? extends org.apache.lucene.util.Attribute>, java.lang.String, java.lang.Object) in the same order, but possibly different values. So don't automatically exclude e.g. null properties!

Important for migration to Lucene 6: The default implementation is implemented for backwards compatibility in Lucene 5 and calls AttributeReflector.reflect(java.lang.Class<? extends org.apache.lucene.util.Attribute>, 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.

Please don't use the default implementation anymore, because it will be made abstract in Lucene 6! See above for implementation example.

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 AttributeImpl clone()

In most cases the clone is, and should be, deep in order to be able to properly capture the state of all attributes.

Overrides:

clone in class Object