org.apache.lucene.analysis.tokenattributes

Class PositionIncrementAttributeImpl

java.lang.Object

org.apache.lucene.util.AttributeImpl

org.apache.lucene.analysis.tokenattributes.PositionIncrementAttributeImpl

All Implemented Interfaces:

Serializable, Cloneable, PositionIncrementAttribute, Attribute

public class PositionIncrementAttributeImpl
extends AttributeImpl
implements PositionIncrementAttribute, Cloneable, Serializable

The positionIncrement determines the position of this token relative to the previous Token in a TokenStream, used in phrase searching.

The default value is one.

Some common uses for this are:

• Set it to zero to put multiple terms in the same position. This is useful if, e.g., a word has multiple stems. Searches for phrases including either stem will match. In this case, all but the first stem's increment should be set to zero: the increment of the first instance should be one. Repeating a token with an increment of zero can also be used to boost the scores of matches on that token.
• Set it to values greater than one to inhibit exact phrase matches. If, for example, one does not want phrases to match across removed stop words, then one could build a stop word filter that removes stop words and also sets the increment to the number of stop words removed before each non-stop word. Then exact phrase queries will only match when the terms occur with no intervening stop words.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
PositionIncrementAttributeImpl()

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clears the values in this AttributeImpl and resets it to its default value.
void	copyTo(AttributeImpl target) Copies the values from this Attribute into the passed-in target attribute.
boolean	equals(Object other) All values used for computation of AttributeImpl.hashCode() should be checked here for equality.
int	getPositionIncrement() Returns the position increment of this Token.
int	hashCode() Subclasses must implement this method and should compute a hashCode similar to this:
void	setPositionIncrement(int positionIncrement) Set the position increment.

Methods inherited from class org.apache.lucene.util.AttributeImpl

clone, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

PositionIncrementAttributeImpl

public PositionIncrementAttributeImpl()

Method Detail

setPositionIncrement

public void setPositionIncrement(int positionIncrement)

Set the position increment. The default value is one.

Specified by:

setPositionIncrement in interface PositionIncrementAttribute

Parameters:

positionIncrement - the distance from the prior term

getPositionIncrement

public int getPositionIncrement()

Returns the position increment of this Token.

Specified by:

getPositionIncrement in interface PositionIncrementAttribute

See Also:

setPositionIncrement(int)

clear

public void clear()

Description copied from class: AttributeImpl

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.

Specified by:

clear in class AttributeImpl

equals

public boolean equals(Object other)

Description copied from class: AttributeImpl

All values used for computation of AttributeImpl.hashCode() should be checked here for equality. see also Object.equals(Object)

Specified by:

equals in class AttributeImpl

hashCode

public int hashCode()

Description copied from class: AttributeImpl

Subclasses must implement this method and should compute a hashCode similar to this:

   public int hashCode() {
     int code = startOffset;
     code = code * 31 + endOffset;
     return code;
   }
 

see also AttributeImpl.equals(Object)

Specified by:

hashCode in class AttributeImpl

copyTo

public void copyTo(AttributeImpl target)

Description copied from class: AttributeImpl

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

Specified by:

copyTo in class AttributeImpl