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

All Implemented Interfaces:

Closeable, AutoCloseable, Searchable
```
public class IndexSearcher
extends Searcher
```
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 IndexReader.openIfChanged(org.apache.lucene.index.IndexReader) 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 (IndexReader.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.

Field Summary

Fields
Modifier and Type Field Description

protected int[] docStarts

protected IndexReader[] subReaders

protected IndexSearcher[] subSearchers

Constructor Summary

Constructors
Constructor	Description
`IndexSearcher(IndexReader r)`	Creates a searcher searching the provided index.
`IndexSearcher(IndexReader r, ExecutorService executor)`	Runs searches for each segment separately, using the provided ExecutorService.
`IndexSearcher(IndexReader reader, IndexReader[] subReaders, int[] docStarts)`	Expert: directly specify the reader, subReaders and their docID starts.
`IndexSearcher(IndexReader reader, IndexReader[] subReaders, int[] docStarts, ExecutorService executor)`	Expert: directly specify the reader, subReaders and their docID starts, and an ExecutorService.
`IndexSearcher(Directory path)`	Deprecated. use `IndexSearcher(IndexReader)` instead.
`IndexSearcher(Directory path, boolean readOnly)`	Deprecated. Use `IndexSearcher(IndexReader)` instead.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`close()`	Note that the underlying IndexReader is not closed, if IndexSearcher was constructed with IndexSearcher(IndexReader r).
`Weight`	`createNormalizedWeight(Query query)`	Creates a normalized weight for a top-level `Query`.
`Document`	`doc(int docID)`	Returns the stored fields of document `i`.
`Document`	`doc(int docID, FieldSelector fieldSelector)`	Get the `Document` at the `n`^th position.
`int`	`docFreq(Term term)`	Returns total docFreq for this term.
`Explanation`	`explain(Query query, int doc)`	Returns an Explanation that describes how `doc` scored against `query`.
`Explanation`	`explain(Weight weight, int doc)`	Expert: low-level implementation method Returns an Explanation that describes how `doc` scored against `weight`.
`protected void`	`gatherSubReaders(List<IndexReader> allSubReaders, IndexReader r)`
`IndexReader`	`getIndexReader()`	Return the `IndexReader` this searches.
`Similarity`	`getSimilarity()`	Expert: Return the Similarity implementation used by this Searcher.
`IndexReader[]`	`getSubReaders()`	Returns the atomic subReaders used by this searcher.
`int`	`maxDoc()`	Expert: Returns one greater than the largest possible document number.
`Query`	`rewrite(Query original)`	Expert: called to re-write queries into primitive queries.
`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.
`void`	`search(Query query, Filter filter, Collector results)`	Lower-level search API.
`TopDocs`	`search(Weight weight, Filter filter, int nDocs)`	Expert: Low-level search implementation.
`TopFieldDocs`	`search(Weight weight, Filter filter, int nDocs, Sort sort)`	Expert: Low-level search implementation with arbitrary sorting.
`protected TopFieldDocs`	`search(Weight weight, Filter filter, int nDocs, Sort sort, boolean fillFields)`	Just like `search(Weight, Filter, int, Sort)`, but you choose whether or not the fields in the returned `FieldDoc` instances should be set by specifying fillFields.
`void`	`search(Weight weight, Filter filter, Collector collector)`	Lower-level search API.
`protected TopDocs`	`search(Weight weight, Filter filter, 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, 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`).
`void`	`setDefaultFieldSortScoring(boolean doTrackScores, boolean doMaxScore)`	By default, no scores are computed when sorting by field (using `search(Query,Filter,int,Sort)`).
`void`	`setSimilarity(Similarity similarity)`	Expert: Set the Similarity implementation used by this Searcher.
`String`	`toString()`

Methods inherited from class org.apache.lucene.search.Searcher
createWeight, docFreqs

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

- Field Detail
  - subReaders
```
protected final IndexReader[] subReaders
```
  - docStarts
```
protected final int[] docStarts
```
  - subSearchers
```
protected final IndexSearcher[] subSearchers
```
- Constructor Detail
  - IndexSearcher
```
@Deprecated
public IndexSearcher(Directory path)
              throws CorruptIndexException,
                     IOException
```
    Deprecated.
    use IndexSearcher(IndexReader) instead.
    
    Creates a searcher searching the index in the named directory, with readOnly=true
    
    Parameters:
    
    path - directory where IndexReader will be opened
    
    Throws:
    
    CorruptIndexException - if the index is corrupt
    
    IOException - if there is a low-level IO error
  - IndexSearcher
```
@Deprecated
public IndexSearcher(Directory path,
                     boolean readOnly)
              throws CorruptIndexException,
                     IOException
```
    Deprecated.
    Use IndexSearcher(IndexReader) instead.
    
    Creates a searcher searching the index in the named directory. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the underlying IndexReader.
    
    Parameters:
    
    path - directory where IndexReader will be opened
    
    readOnly - if true, the underlying IndexReader will be opened readOnly
    
    Throws:
    
    CorruptIndexException - if the index is corrupt
    
    IOException - if there is a low-level IO error
  - 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).
    
    WARNING: This API is experimental and might change in incompatible ways in the next release.
  - IndexSearcher
```
public IndexSearcher(IndexReader reader,
                     IndexReader[] subReaders,
                     int[] docStarts)
```
    Expert: directly specify the reader, subReaders and their docID starts.
    
    WARNING: This API is experimental and might change in incompatible ways in the next release.
  - IndexSearcher
```
public IndexSearcher(IndexReader reader,
                     IndexReader[] subReaders,
                     int[] docStarts,
                     ExecutorService executor)
```
    Expert: directly specify the reader, subReaders and their docID starts, and an ExecutorService. In this case, each segment will be separately searched using the 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).
    
    WARNING: This API is experimental and might change in incompatible ways in the next release.
- Method Detail
  - gatherSubReaders
```
protected void gatherSubReaders(List<IndexReader> allSubReaders,
                                IndexReader r)
```
  - getIndexReader
```
public IndexReader getIndexReader()
```
    Return the IndexReader this searches.
  - getSubReaders
```
public IndexReader[] getSubReaders()
```
    Returns the atomic subReaders used by this searcher.
  - maxDoc
```
public int maxDoc()
```
    Expert: Returns one greater than the largest possible document number.
    
    Specified by:
    
    maxDoc in interface Searchable
    
    Specified by:
    
    maxDoc in class Searcher
    
    See Also:
    
    IndexReader.maxDoc()
  - docFreq
```
public int docFreq(Term term)
            throws IOException
```
    Returns total docFreq for this term.
    
    Specified by:
    
    docFreq in interface Searchable
    
    Specified by:
    
    docFreq in class Searcher
    
    Throws:
    
    IOException
    
    See Also:
    
    IndexReader.docFreq(Term)
  - doc
```
public Document doc(int docID)
             throws CorruptIndexException,
                    IOException
```
    Description copied from interface: Searchable
    
    Returns the stored fields of document i.
    
    Specified by:
    
    doc in interface Searchable
    
    Specified by:
    
    doc in class Searcher
    
    Throws:
    
    CorruptIndexException - if the index is corrupt
    
    IOException - if there is a low-level IO error
    
    See Also:
    
    IndexReader.document(int)
  - doc
```
public Document doc(int docID,
                    FieldSelector fieldSelector)
             throws CorruptIndexException,
                    IOException
```
    Description copied from interface: Searchable
    
    Get the Document at the n^th position. The FieldSelector may be used to determine what Fields to load and how they should be loaded. NOTE: If the underlying Reader (more specifically, the underlying FieldsReader) is closed before the lazy Field is loaded an exception may be thrown. If you want the value of a lazy Field to be available after closing you must explicitly load it or fetch the Document again with a new loader.
    
    Specified by:
    
    doc in interface Searchable
    
    Specified by:
    
    doc in class Searcher
    
    Parameters:
    
    docID - Get the document at the n^th position
    
    fieldSelector - The FieldSelector to use to determine what Fields should be loaded on the Document. May be null, in which case all Fields will be loaded.
    
    Returns:
    
    The stored fields of the Document at the nth position
    
    Throws:
    
    CorruptIndexException - if the index is corrupt
    
    IOException - if there is a low-level IO error
    
    See Also:
    
    IndexReader.document(int, FieldSelector), Fieldable, FieldSelector, SetBasedFieldSelector, LoadFirstFieldSelector
  - setSimilarity
```
public void setSimilarity(Similarity similarity)
```
    Expert: Set the Similarity implementation used by this Searcher.
    
    Overrides:
    
    setSimilarity in class Searcher
    
    See Also:
    
    Similarity.setDefault(Similarity)
  - getSimilarity
```
public Similarity getSimilarity()
```
    Description copied from class: Searcher
    
    Expert: Return the Similarity implementation used by this Searcher.
    This defaults to the current value of Similarity.getDefault().
    
    Overrides:
    
    getSimilarity in class Searcher
  - close
```
public void close()
           throws IOException
```
    Note that the underlying IndexReader is not closed, if IndexSearcher was constructed with IndexSearcher(IndexReader r). If the IndexReader was supplied implicitly by specifying a directory, then the IndexReader is closed.
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface Searchable
    
    Specified by:
    
    close in class Searcher
    
    Throws:
    
    IOException
  - 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
    
    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
    
    IOException
  - search
```
public TopDocs search(Query query,
                      int n)
               throws IOException
```
    Finds the top n hits for query.
    
    Overrides:
    
    search in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    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.
    
    Overrides:
    
    search in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    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.
    Collector-based access to remote indexes is discouraged.
    Applications should only use this if they need all of the matching documents. The high-level search API (Searcher.search(Query, Filter, int)) is usually more efficient, as it skips non-high-scoring hits.
    
    Overrides:
    
    search in class Searcher
    
    Parameters:
    
    query - to match documents
    
    filter - if non-null, used to permit documents to be collected.
    
    results - to receive hits
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - search
```
public void search(Query query,
                   Collector results)
            throws IOException
```
    Lower-level search API.
    Collector.collect(int) is called for every matching document.
    Applications should only use this if they need all of the matching documents. The high-level search API (Searcher.search(Query, int)) is usually more efficient, as it skips non-high-scoring hits.
    Note: The score passed to this method is a raw score. In other words, the score will not necessarily be a float whose value is between 0 and 1.
    
    Overrides:
    
    search in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    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 setDefaultFieldSortScoring(boolean, boolean) to enable scoring.
    
    Overrides:
    
    search in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - search
```
public TopFieldDocs search(Query query,
                           int n,
                           Sort sort)
                    throws IOException
```
    Search implementation with arbitrary sorting and no filter.
    
    Overrides:
    
    search in class Searcher
    
    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
  - search
```
public TopDocs search(Weight weight,
                      Filter filter,
                      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 Searcher.search(Query,int) or Searcher.search(Query,Filter,int) instead.
    
    Specified by:
    
    search in interface Searchable
    
    Specified by:
    
    search in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - search
```
protected TopDocs search(Weight weight,
                         Filter filter,
                         ScoreDoc after,
                         int nDocs)
                  throws IOException
```
    Expert: Low-level search implementation. Finds the top n hits for query, applying filter if non-null, returning results after after.
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - search
```
public TopFieldDocs search(Weight weight,
                           Filter filter,
                           int nDocs,
                           Sort sort)
                    throws IOException
```
    Expert: Low-level 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.
    Applications should usually call Searcher.search(Query,Filter,int,Sort) instead.
    
    Specified by:
    
    search in interface Searchable
    
    Specified by:
    
    search in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - search
```
protected TopFieldDocs search(Weight weight,
                              Filter filter,
                              int nDocs,
                              Sort sort,
                              boolean fillFields)
                       throws IOException
```
    Just like search(Weight, Filter, int, Sort), but you choose whether or not the fields in the returned FieldDoc instances should be set by specifying fillFields.
    NOTE: this does not compute scores by default. If you need scores, create a TopFieldCollector instance by calling TopFieldCollector.create(org.apache.lucene.search.Sort, int, boolean, boolean, boolean, boolean) and then pass that to search(Weight, Filter, Collector).
    
    Throws:
    
    IOException
  - search
```
public void search(Weight weight,
                   Filter filter,
                   Collector collector)
            throws IOException
```
    Lower-level search API.
    Collector.collect(int) is called for every document.
    Collector-based access to remote indexes is discouraged.
    Applications should only use this if they need all of the matching documents. The high-level search API (Searcher.search(Query,int)) is usually more efficient, as it skips non-high-scoring hits.
    
    Specified by:
    
    search in interface Searchable
    
    Specified by:
    
    search in class Searcher
    
    Parameters:
    
    weight - to match documents
    
    filter - if non-null, used to permit documents to be collected.
    
    collector - to receive hits
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - rewrite
```
public Query rewrite(Query original)
              throws IOException
```
    Expert: called to re-write queries into primitive queries.
    
    Specified by:
    
    rewrite in interface Searchable
    
    Specified by:
    
    rewrite in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    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.
    
    Overrides:
    
    explain in class Searcher
    
    Throws:
    
    IOException
  - explain
```
public 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 Searcher.explain(Query, int).
    
    Specified by:
    
    explain in interface Searchable
    
    Specified by:
    
    explain in class Searcher
    
    Throws:
    
    BooleanQuery.TooManyClauses
    
    IOException
  - setDefaultFieldSortScoring
```
public void setDefaultFieldSortScoring(boolean doTrackScores,
                                       boolean doMaxScore)
```
    By default, no scores are computed when sorting by field (using search(Query,Filter,int,Sort)). You can change that, per IndexSearcher instance, by calling this method. Note that this will incur a CPU cost.
    
    Parameters:
    
    doTrackScores - If true, then scores are returned for every matching document in TopFieldDocs.
    
    doMaxScore - If true, then the max score for all matching docs is computed.
  - 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.Searcher) called, afterwards the Weight is normalized. The returned Weight can then directly be used to get a Scorer.
    
    Overrides:
    
    createNormalizedWeight in class Searcher
    
    Throws:
    
    IOException
    
    NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Modifier and Type	Field	Description
`protected int[]`	`docStarts`
`protected IndexReader[]`	`subReaders`
`protected IndexSearcher[]`	`subSearchers`

Class IndexSearcher

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.lucene.search.Searcher

Methods inherited from class java.lang.Object

Field Detail

subReaders

docStarts

subSearchers

Constructor Detail

IndexSearcher

IndexSearcher

IndexSearcher

IndexSearcher

IndexSearcher

IndexSearcher

Method Detail

gatherSubReaders

getIndexReader

getSubReaders

maxDoc

docFreq

doc

doc

setSimilarity

getSimilarity

close

searchAfter

searchAfter

search

search

search

search

search

search

search

search

search

search

search

rewrite

explain

explain

setDefaultFieldSortScoring

createNormalizedWeight

toString