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

```
public class IndexSearcher
extends Object
```
Implements search over a single IndexReader.
Applications usually need only call the inherited search(Query,int) or search(Query,Filter,int) methods. For performance reasons, if your index is unchanging, you should share a single IndexSearcher instance across multiple searches instead of creating a new one per-search. If your index has changed and you wish to see the changes reflected in searching, you should use DirectoryReader.openIfChanged(DirectoryReader) to obtain a new reader and then create a new IndexSearcher from that. Also, for low-latency turnaround it's best to use a near-real-time reader (DirectoryReader.open(IndexWriter,boolean)). Once you have a new IndexReader, it's relatively cheap to create a new IndexSearcher from it.
NOTE: IndexSearcher instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexSearcher instance; use your own (non-Lucene) objects instead.

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class IndexSearcher.LeafSlice
A class holding a subset of the IndexSearchers leaf contexts to be executed within a single thread.

Field Summary

Fields
Modifier and Type	Field	Description
`protected List<AtomicReaderContext>`	`leafContexts`
`protected IndexSearcher.LeafSlice[]`	`leafSlices`	used with executor - each slice holds a set of leafs executed within one thread
`protected IndexReaderContext`	`readerContext`

Constructor Summary

Constructors
Constructor	Description
`IndexSearcher(IndexReader r)`	Creates a searcher searching the provided index.
`IndexSearcher(IndexReaderContext context)`	Creates a searcher searching the provided top-level `IndexReaderContext`.
`IndexSearcher(IndexReaderContext context, ExecutorService executor)`	Creates a searcher searching the provided top-level `IndexReaderContext`.
`IndexSearcher(IndexReader r, ExecutorService executor)`	Runs searches for each segment separately, using the provided ExecutorService.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`CollectionStatistics`	`collectionStatistics(String field)`	Returns `CollectionStatistics` for a field.
`Weight`	`createNormalizedWeight(Query query)`	Creates a normalized weight for a top-level `Query`.
`Document`	`doc(int docID)`	Sugar for `.getIndexReader().document(docID)`
`Document`	`doc(int docID, Set<String> fieldsToLoad)`	Sugar for `.getIndexReader().document(docID, fieldsToLoad)`
`void`	`doc(int docID, StoredFieldVisitor fieldVisitor)`	Sugar for `.getIndexReader().document(docID, fieldVisitor)`
`Document`	`document(int docID, Set<String> fieldsToLoad)`	Deprecated. Use `doc(int, Set)` instead.
`Explanation`	`explain(Query query, int doc)`	Returns an Explanation that describes how `doc` scored against `query`.
`protected Explanation`	`explain(Weight weight, int doc)`	Expert: low-level implementation method Returns an Explanation that describes how `doc` scored against `weight`.
`static Similarity`	`getDefaultSimilarity()`	Expert: returns a default Similarity instance.
`IndexReader`	`getIndexReader()`	Return the `IndexReader` this searches.
`Similarity`	`getSimilarity()`
`IndexReaderContext`	`getTopReaderContext()`	Returns this searchers the top-level `IndexReaderContext`.
`Query`	`rewrite(Query original)`	Expert: called to re-write queries into primitive queries.
`protected void`	`search(List<AtomicReaderContext> leaves, Weight weight, Collector collector)`	Lower-level search API.
`protected TopFieldDocs`	`search(List<AtomicReaderContext> leaves, Weight weight, FieldDoc after, int nDocs, Sort sort, boolean fillFields, boolean doDocScores, boolean doMaxScore)`	Just like `search(Weight, int, Sort, boolean, boolean)`, but you choose whether or not the fields in the returned `FieldDoc` instances should be set by specifying fillFields.
`protected TopDocs`	`search(List<AtomicReaderContext> leaves, Weight weight, ScoreDoc after, int nDocs)`	Expert: Low-level search implementation.
`TopDocs`	`search(Query query, int n)`	Finds the top `n` hits for `query`.
`TopFieldDocs`	`search(Query query, int n, Sort sort)`	Search implementation with arbitrary sorting and no filter.
`void`	`search(Query query, Collector results)`	Lower-level search API.
`TopDocs`	`search(Query query, Filter filter, int n)`	Finds the top `n` hits for `query`, applying `filter` if non-null.
`TopFieldDocs`	`search(Query query, Filter filter, int n, Sort sort)`	Search implementation with arbitrary sorting.
`TopFieldDocs`	`search(Query query, Filter filter, int n, Sort sort, boolean doDocScores, boolean doMaxScore)`	Search implementation with arbitrary sorting, plus control over whether hit scores and max score should be computed.
`void`	`search(Query query, Filter filter, Collector results)`	Lower-level search API.
`protected TopFieldDocs`	`search(Weight weight, int nDocs, Sort sort, boolean doDocScores, boolean doMaxScore)`	Expert: Low-level search implementation with arbitrary sorting and control over whether hit scores and max score should be computed.
`protected TopFieldDocs`	`search(Weight weight, FieldDoc after, int nDocs, Sort sort, boolean fillFields, boolean doDocScores, boolean doMaxScore)`	Just like `search(Weight, int, Sort, boolean, boolean)`, but you choose whether or not the fields in the returned `FieldDoc` instances should be set by specifying fillFields.
`protected TopDocs`	`search(Weight weight, ScoreDoc after, int nDocs)`	Expert: Low-level search implementation.
`TopDocs`	`searchAfter(ScoreDoc after, Query query, int n)`	Finds the top `n` hits for `query` where all results are after a previous result (`after`).
`TopDocs`	`searchAfter(ScoreDoc after, Query query, int n, Sort sort)`	Finds the top `n` hits for `query` where all results are after a previous result (`after`).
`TopDocs`	`searchAfter(ScoreDoc after, Query query, Filter filter, int n)`	Finds the top `n` hits for `query`, applying `filter` if non-null, where all results are after a previous result (`after`).
`TopDocs`	`searchAfter(ScoreDoc after, Query query, Filter filter, int n, Sort sort)`	Finds the top `n` hits for `query`, applying `filter` if non-null, where all results are after a previous result (`after`).
`TopDocs`	`searchAfter(ScoreDoc after, Query query, Filter filter, int n, Sort sort, boolean doDocScores, boolean doMaxScore)`	Finds the top `n` hits for `query` where all results are after a previous result (`after`), allowing control over whether hit scores and max score should be computed.
`void`	`setSimilarity(Similarity similarity)`	Expert: Set the Similarity implementation used by this IndexSearcher.
`protected IndexSearcher.LeafSlice[]`	`slices(List<AtomicReaderContext> leaves)`	Expert: Creates an array of leaf slices each holding a subset of the given leaves.
`TermStatistics`	`termStatistics(Term term, TermContext context)`	Returns `TermStatistics` for a term.
`String`	`toString()`
`protected Query`	`wrapFilter(Query query, Filter filter)`

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

- Field Detail
  - readerContext
```
protected final IndexReaderContext readerContext
```
  - leafContexts
```
protected final List<AtomicReaderContext> leafContexts
```
  - leafSlices
```
protected final IndexSearcher.LeafSlice[] leafSlices
```
    used with executor - each slice holds a set of leafs executed within one thread
- Constructor Detail
  - IndexSearcher
```
public IndexSearcher(IndexReader r)
```
    Creates a searcher searching the provided index.
  - IndexSearcher
```
public IndexSearcher(IndexReader r,
                     ExecutorService executor)
```
    Runs searches for each segment separately, using the provided ExecutorService. IndexSearcher will not shutdown/awaitTermination this ExecutorService on close; you must do so, eventually, on your own. NOTE: if you are using NIOFSDirectory, do not use the shutdownNow method of ExecutorService as this uses Thread.interrupt under-the-hood which can silently close file descriptors (see LUCENE-2239).
  - IndexSearcher
```
public IndexSearcher(IndexReaderContext context,
                     ExecutorService executor)
```
    Creates a searcher searching the provided top-level IndexReaderContext.
    Given a non-null ExecutorService this method runs searches for each segment separately, using the provided ExecutorService. IndexSearcher will not shutdown/awaitTermination this ExecutorService on close; you must do so, eventually, on your own. NOTE: if you are using NIOFSDirectory, do not use the shutdownNow method of ExecutorService as this uses Thread.interrupt under-the-hood which can silently close file descriptors (see LUCENE-2239).
    
    See Also:
    
    IndexReaderContext, IndexReader.getContext()
  - IndexSearcher
```
public IndexSearcher(IndexReaderContext context)
```
    Creates a searcher searching the provided top-level IndexReaderContext.
    
    See Also:
    
    IndexReaderContext, IndexReader.getContext()
- Method Detail
  - getDefaultSimilarity
```
public static Similarity getDefaultSimilarity()
```
    Expert: returns a default Similarity instance. In general, this method is only called to initialize searchers and writers. User code and query implementations should respect getSimilarity().
  - slices
```
protected IndexSearcher.LeafSlice[] slices(List<AtomicReaderContext> leaves)
```
    Expert: Creates an array of leaf slices each holding a subset of the given leaves. Each IndexSearcher.LeafSlice is executed in a single thread. By default there will be one IndexSearcher.LeafSlice per leaf (AtomicReaderContext).
  - getIndexReader
```
public IndexReader getIndexReader()
```
    Return the IndexReader this searches.
  - doc
```
public Document doc(int docID)
             throws IOException
```
    Sugar for .getIndexReader().document(docID)
    
    Throws:
    
    IOException
    
    See Also:
    
    IndexReader.document(int)
  - doc
```
public void doc(int docID,
                StoredFieldVisitor fieldVisitor)
         throws IOException
```
    Sugar for .getIndexReader().document(docID, fieldVisitor)
    
    Throws:
    
    IOException
    
    See Also:
    
    IndexReader.document(int, StoredFieldVisitor)
  - doc
```
public Document doc(int docID,
                    Set<String> fieldsToLoad)
             throws IOException
```
    Sugar for .getIndexReader().document(docID, fieldsToLoad)
    
    Throws:
    
    IOException
    
    See Also:
    
    IndexReader.document(int, Set)
  - document
```
@Deprecated
public final Document document(int docID,
                               Set<String> fieldsToLoad)
                        throws IOException
```
    Deprecated.
    Use doc(int, Set) instead.
    
    Throws:
    
    IOException
  - setSimilarity
```
public void setSimilarity(Similarity similarity)
```
    Expert: Set the Similarity implementation used by this IndexSearcher.
  - getSimilarity
```
public Similarity getSimilarity()
```
  - wrapFilter
```
protected Query wrapFilter(Query query,
                           Filter filter)
```
  - searchAfter
```
public TopDocs searchAfter(ScoreDoc after,
                           Query query,
                           int n)
                    throws IOException
```
    Finds the top n hits for query where all results are after a previous result (after).
    By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - searchAfter
```
public TopDocs searchAfter(ScoreDoc after,
                           Query query,
                           Filter filter,
                           int n)
                    throws IOException
```
    Finds the top n hits for query, applying filter if non-null, where all results are after a previous result (after).
    By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public TopDocs search(Query query,
                      int n)
               throws IOException
```
    Finds the top n hits for query.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public TopDocs search(Query query,
                      Filter filter,
                      int n)
               throws IOException
```
    Finds the top n hits for query, applying filter if non-null.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public void search(Query query,
                   Filter filter,
                   Collector results)
            throws IOException
```
    Lower-level search API.
    Collector.collect(int) is called for every matching document.
    
    Parameters:
    
    query - to match documents
    
    filter - if non-null, used to permit documents to be collected.
    
    results - to receive hits
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public void search(Query query,
                   Collector results)
            throws IOException
```
    Lower-level search API.
    Collector.collect(int) is called for every matching document.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public TopFieldDocs search(Query query,
                           Filter filter,
                           int n,
                           Sort sort)
                    throws IOException
```
    Search implementation with arbitrary sorting. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort.
    NOTE: this does not compute scores by default; use search(Query,Filter,int,Sort,boolean,boolean) to control scoring.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public TopFieldDocs search(Query query,
                           Filter filter,
                           int n,
                           Sort sort,
                           boolean doDocScores,
                           boolean doMaxScore)
                    throws IOException
```
    Search implementation with arbitrary sorting, plus control over whether hit scores and max score should be computed. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort. If doDocScores is true then the score of each hit will be computed and returned. If doMaxScore is true then the maximum score over all collected hits will be computed.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - searchAfter
```
public TopDocs searchAfter(ScoreDoc after,
                           Query query,
                           Filter filter,
                           int n,
                           Sort sort)
                    throws IOException
```
    Finds the top n hits for query, applying filter if non-null, where all results are after a previous result (after).
    By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
public TopFieldDocs search(Query query,
                           int n,
                           Sort sort)
                    throws IOException
```
    Search implementation with arbitrary sorting and no filter.
    
    Parameters:
    
    query - The query to search for
    
    n - Return only the top n results
    
    sort - The Sort object
    
    Returns:
    
    The top docs, sorted according to the supplied Sort instance
    
    Throws:
    
    IOException - if there is a low-level I/O error
  - searchAfter
```
public TopDocs searchAfter(ScoreDoc after,
                           Query query,
                           int n,
                           Sort sort)
                    throws IOException
```
    Finds the top n hits for query where all results are after a previous result (after).
    By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - searchAfter
```
public TopDocs searchAfter(ScoreDoc after,
                           Query query,
                           Filter filter,
                           int n,
                           Sort sort,
                           boolean doDocScores,
                           boolean doMaxScore)
                    throws IOException
```
    Finds the top n hits for query where all results are after a previous result (after), allowing control over whether hit scores and max score should be computed.
    By passing the bottom result from a previous page as after, this method can be used for efficient 'deep-paging' across potentially large result sets. If doDocScores is true then the score of each hit will be computed and returned. If doMaxScore is true then the maximum score over all collected hits will be computed.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
protected TopDocs search(Weight weight,
                         ScoreDoc after,
                         int nDocs)
                  throws IOException
```
    Expert: Low-level search implementation. Finds the top n hits for query, applying filter if non-null.
    Applications should usually call search(Query,int) or search(Query,Filter,int) instead.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
protected TopDocs search(List<AtomicReaderContext> leaves,
                         Weight weight,
                         ScoreDoc after,
                         int nDocs)
                  throws IOException
```
    Expert: Low-level search implementation. Finds the top n hits for query.
    Applications should usually call search(Query,int) or search(Query,Filter,int) instead.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
protected TopFieldDocs search(Weight weight,
                              int nDocs,
                              Sort sort,
                              boolean doDocScores,
                              boolean doMaxScore)
                       throws IOException
```
    Expert: Low-level search implementation with arbitrary sorting and control over whether hit scores and max score should be computed. Finds the top n hits for query and sorting the hits by the criteria in sort.
    Applications should usually call search(Query,Filter,int,Sort) instead.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - search
```
protected TopFieldDocs search(Weight weight,
                              FieldDoc after,
                              int nDocs,
                              Sort sort,
                              boolean fillFields,
                              boolean doDocScores,
                              boolean doMaxScore)
                       throws IOException
```
    Just like search(Weight, int, Sort, boolean, boolean), but you choose whether or not the fields in the returned FieldDoc instances should be set by specifying fillFields.
    
    Throws:
    
    IOException
  - search
```
protected TopFieldDocs search(List<AtomicReaderContext> leaves,
                              Weight weight,
                              FieldDoc after,
                              int nDocs,
                              Sort sort,
                              boolean fillFields,
                              boolean doDocScores,
                              boolean doMaxScore)
                       throws IOException
```
    Just like search(Weight, int, Sort, boolean, boolean), but you choose whether or not the fields in the returned FieldDoc instances should be set by specifying fillFields.
    
    Throws:
    
    IOException
  - search
```
protected void search(List<AtomicReaderContext> leaves,
                      Weight weight,
                      Collector collector)
               throws IOException
```
    Lower-level search API.
    Collector.collect(int) is called for every document.
    
    NOTE: this method executes the searches on all given leaves exclusively. To search across all the searchers leaves use leafContexts.
    
    Parameters:
    
    leaves - the searchers leaves to execute the searches on
    
    weight - to match documents
    
    collector - to receive hits
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - rewrite
```
public Query rewrite(Query original)
              throws IOException
```
    Expert: called to re-write queries into primitive queries.
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - explain
```
public Explanation explain(Query query,
                           int doc)
                    throws IOException
```
    Returns an Explanation that describes how doc scored against query.
    This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.
    
    Throws:
    
    IOException
  - explain
```
protected Explanation explain(Weight weight,
                              int doc)
                       throws IOException
```
    Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.
    This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.
    Applications should call explain(Query, int).
    
    Throws:
    
    BooleanQuery.TooManyClauses - If a query would exceed BooleanQuery.getMaxClauseCount() clauses.
    
    IOException
  - createNormalizedWeight
```
public Weight createNormalizedWeight(Query query)
                              throws IOException
```
    Creates a normalized weight for a top-level Query. The query is rewritten by this method and Query.createWeight(org.apache.lucene.search.IndexSearcher) called, afterwards the Weight is normalized. The returned Weight can then directly be used to get a Scorer.
    
    Throws:
    
    IOException
  - getTopReaderContext
```
public IndexReaderContext getTopReaderContext()
```
    Returns this searchers the top-level IndexReaderContext.
    
    See Also:
    
    IndexReader.getContext()
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - termStatistics
```
public TermStatistics termStatistics(Term term,
                                     TermContext context)
                              throws IOException
```
    Returns TermStatistics for a term. This can be overridden for example, to return a term's statistics across a distributed collection.
    
    Throws:
    
    IOException
  - collectionStatistics
```
public CollectionStatistics collectionStatistics(String field)
                                          throws IOException
```
    Returns CollectionStatistics for a field. This can be overridden for example, to return a field's statistics across a distributed collection.
    
    Throws:
    
    IOException

Class IndexSearcher

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

readerContext

leafContexts

leafSlices

Constructor Detail

IndexSearcher

IndexSearcher

IndexSearcher

IndexSearcher

Method Detail

getDefaultSimilarity

slices

getIndexReader

doc

doc

doc

document

setSimilarity

getSimilarity

wrapFilter

searchAfter

searchAfter

search

search

search

search

search

search

searchAfter

search

searchAfter

searchAfter

search

search

search

search

search

search

rewrite

explain

explain

createNormalizedWeight

getTopReaderContext

toString

termStatistics

collectionStatistics