java.lang.Object
- org.apache.lucene.search.Weight

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

BooleanQuery.BooleanWeight, ConstantScoreQuery.ConstantWeight, DisjunctionMaxQuery.DisjunctionMaxWeight, SpanWeight
```
public abstract class Weight
extends Object
implements Serializable
```
Expert: Calculate query weights and build query scorers.
The purpose of Weight is to ensure searching does not modify a Query, so that a Query instance can be reused.
Searcher dependent state of the query should reside in the Weight.
IndexReader dependent state should reside in the Scorer.
A Weight is used in the following way:
1. A Weight is constructed by a top-level query, given a Searcher (Query.createWeight(Searcher)).
2. The sumOfSquaredWeights() method is called on the Weight to compute the query normalization factor Similarity.queryNorm(float) of the query clauses contained in the query.
3. The query normalization factor is passed to normalize(float). At this point the weighting is complete.
4. A Scorer is constructed by scorer(IndexReader,boolean,boolean).
Since:

2.9

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor Description

Weight()

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract Explanation`	`explain(IndexReader reader, int doc)`	An explanation of the score computation for the named document.
`abstract Query`	`getQuery()`	The query that this concerns.
`abstract float`	`getValue()`	The weight for this query.
`abstract void`	`normalize(float norm)`	Assigns the query normalization factor to this.
`abstract Scorer`	`scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer)`	Returns a `Scorer` which scores documents in/out-of order according to `scoreDocsInOrder`.
`boolean`	`scoresDocsOutOfOrder()`	Returns true iff this implementation scores docs only out of order.
`abstract float`	`sumOfSquaredWeights()`	The sum of squared weights of contained query clauses.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Weight
```
public Weight()
```
- Method Detail
  - explain
```
public abstract Explanation explain(IndexReader reader,
                                    int doc)
                             throws IOException
```
    An explanation of the score computation for the named document.
    
    Parameters:
    
    reader - sub-reader containing the give doc
    
    doc -
    
    Returns:
    
    an Explanation for the score
    
    Throws:
    
    IOException
  - getQuery
```
public abstract Query getQuery()
```
    The query that this concerns.
  - getValue
```
public abstract float getValue()
```
    The weight for this query.
  - normalize
```
public abstract void normalize(float norm)
```
    Assigns the query normalization factor to this.
  - scorer
```
public abstract Scorer scorer(IndexReader reader,
                              boolean scoreDocsInOrder,
                              boolean topScorer)
                       throws IOException
```
    Returns a Scorer which scores documents in/out-of order according to scoreDocsInOrder.
    NOTE: even if scoreDocsInOrder is false, it is recommended to check whether the returned Scorer indeed scores documents out of order (i.e., call scoresDocsOutOfOrder()), as some Scorer implementations will always return documents in-order.
    NOTE: null can be returned if no documents will be scored by this query.
    
    Parameters:
    
    reader - the IndexReader for which to return the Scorer.
    
    scoreDocsInOrder - specifies whether in-order scoring of documents is required. Note that if set to false (i.e., out-of-order scoring is required), this method can return whatever scoring mode it supports, as every in-order scorer is also an out-of-order one. However, an out-of-order scorer may not support DocIdSetIterator.nextDoc() and/or DocIdSetIterator.advance(int), therefore it is recommended to request an in-order scorer if use of these methods is required.
    
    topScorer - if true, Scorer.score(Collector) will be called; if false, DocIdSetIterator.nextDoc() and/or DocIdSetIterator.advance(int) will be called.
    
    Returns:
    
    a Scorer which scores documents in/out-of order.
    
    Throws:
    
    IOException
  - sumOfSquaredWeights
```
public abstract float sumOfSquaredWeights()
                                   throws IOException
```
    The sum of squared weights of contained query clauses.
    
    Throws:
    
    IOException
  - scoresDocsOutOfOrder
```
public boolean scoresDocsOutOfOrder()
```
    Returns true iff this implementation scores docs only out of order. This method is used in conjunction with Collector's acceptsDocsOutOfOrder and scorer(org.apache.lucene.index.IndexReader, boolean, boolean) to create a matching Scorer instance for a given Collector, or vice versa.
    NOTE: the default implementation returns false, i.e. the Scorer scores documents in-order.

Class Weight

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Weight

Method Detail

explain

getQuery

getValue

normalize

scorer

sumOfSquaredWeights

scoresDocsOutOfOrder