java.lang.Object
- org.apache.lucene.index.IndexReader
- - org.apache.lucene.index.MultiReader

All Implemented Interfaces:

Closeable, AutoCloseable, Cloneable

Direct Known Subclasses:

SlowMultiReaderWrapper
```
public class MultiReader
extends IndexReader
implements Cloneable
```
An IndexReader which reads multiple indexes, appending their content.

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader
  IndexReader.ReaderClosedListener

Field Summary

Fields
Modifier and Type Field Description

protected int[] starts

protected IndexReader[] subReaders
- Fields inherited from class org.apache.lucene.index.IndexReader
  hasChanges

Constructor Summary

Constructors
Constructor	Description
`MultiReader(IndexReader... subReaders)`	Construct a MultiReader aggregating the named set of (sub)readers.
`MultiReader(IndexReader[] subReaders, boolean closeSubReaders)`	Construct a MultiReader aggregating the named set of (sub)readers.

Method Summary

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`Object`	`clone()`	Efficiently clones the IndexReader (sharing most internal state).
`IndexReader`	`clone(boolean openReadOnly)`	Deprecated. Write support will be removed in Lucene 4.0.
`int`	`docFreq(Term t)`	Returns the number of documents containing the term `t`.
`protected void`	`doClose()`	Implements close.
`protected void`	`doCommit(Map<String,String> commitUserData)`	Deprecated.
`Document`	`document(int n, FieldSelector fieldSelector)`	Get the `Document` at the `n` ^th position.
`protected void`	`doDelete(int n)`	Deprecated.
`protected IndexReader`	`doOpenIfChanged()`	If the index has changed since it was opened, open and return a new reader; else, return `null`.
`protected IndexReader`	`doOpenIfChanged(boolean openReadOnly)`	Deprecated. Write support will be removed in Lucene 4.0.
`protected void`	`doSetNorm(int n, String field, byte value)`	Deprecated.
`protected void`	`doUndeleteAll()`	Deprecated.
`FieldInfos`	`getFieldInfos()`	Get the `FieldInfos` describing all fields in this reader.
`IndexReader[]`	`getSequentialSubReaders()`	Expert: returns the sequential sub readers that this reader is logically composed of.
`TermFreqVector`	`getTermFreqVector(int n, String field)`	Return a term frequency vector for the specified document and field.
`void`	`getTermFreqVector(int docNumber, String field, TermVectorMapper mapper)`	Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of the `TermFreqVector`.
`void`	`getTermFreqVector(int docNumber, TermVectorMapper mapper)`	Map all the term vectors for all fields in a Document
`TermFreqVector[]`	`getTermFreqVectors(int n)`	Return an array of term frequency vectors for the specified document.
`long`	`getVersion()`	Not implemented.
`boolean`	`hasDeletions()`	Returns true if any documents have been deleted
`boolean`	`hasNorms(String field)`	Returns true if there are norms stored for this field.
`boolean`	`isCurrent()`	Checks recursively if all subreaders are up to date.
`boolean`	`isDeleted(int n)`	Returns true if document n has been deleted
`boolean`	`isOptimized()`	Deprecated.
`int`	`maxDoc()`	Returns one greater than the largest possible document number.
`byte[]`	`norms(String field)`	Returns the byte-encoded normalization factor for the named field of every document.
`void`	`norms(String field, byte[] result, int offset)`	Reads the byte-encoded normalization factor for the named field of every document.
`int`	`numDocs()`	Returns the number of documents in this index.
`protected int`	`readerIndex(int n)`
`TermDocs`	`termDocs()`	Returns an unpositioned `TermDocs` enumerator.
`TermDocs`	`termDocs(Term term)`	Returns an enumeration of all the documents which contain `term`.
`TermPositions`	`termPositions()`	Returns an unpositioned `TermPositions` enumerator.
`TermEnum`	`terms()`	Returns an enumeration of all the terms in the index.
`TermEnum`	`terms(Term term)`	Returns an enumeration of all terms starting at a given term.

Methods inherited from class org.apache.lucene.index.IndexReader
acquireWriteLock, addReaderClosedListener, close, commit, commit, decRef, deleteDocument, deleteDocuments, directory, document, doOpenIfChanged, doOpenIfChanged, ensureOpen, flush, flush, getCommitUserData, getCommitUserData, getCoreCacheKey, getCurrentVersion, getDeletesCacheKey, getIndexCommit, getRefCount, getTermInfosIndexDivisor, getUniqueTermCount, incRef, indexExists, lastModified, listCommits, numDeletedDocs, open, open, open, open, open, open, open, open, open, open, open, openIfChanged, openIfChanged, openIfChanged, openIfChanged, removeReaderClosedListener, reopen, reopen, reopen, reopen, setNorm, setNorm, termPositions, toString, tryIncRef, undeleteAll

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

- Field Detail
  - subReaders
```
protected final IndexReader[] subReaders
```
  - starts
```
protected final int[] starts
```
- Constructor Detail
  - MultiReader
```
public MultiReader(IndexReader... subReaders)
```
    Construct a MultiReader aggregating the named set of (sub)readers. Directory locking for delete, undeleteAll, and setNorm operations is left to the subreaders.
    
    Note that all subreaders are closed if this Multireader is closed.
    
    Parameters:
    
    subReaders - set of (sub)readers
  - MultiReader
```
public MultiReader(IndexReader[] subReaders,
                   boolean closeSubReaders)
```
    Construct a MultiReader aggregating the named set of (sub)readers. Directory locking for delete, undeleteAll, and setNorm operations is left to the subreaders.
    
    Parameters:
    
    closeSubReaders - indicates whether the subreaders should be closed when this MultiReader is closed
    
    subReaders - set of (sub)readers
- Method Detail
  - getFieldInfos
```
public FieldInfos getFieldInfos()
```
    Description copied from class: IndexReader
    
    Get the FieldInfos describing all fields in this reader. NOTE: do not make any changes to the returned FieldInfos!
    
    Specified by:
    
    getFieldInfos in class IndexReader
  - doOpenIfChanged
```
protected IndexReader doOpenIfChanged()
                               throws CorruptIndexException,
                                      IOException
```
    Description copied from class: IndexReader
    
    If the index has changed since it was opened, open and return a new reader; else, return null.
    
    Overrides:
    
    doOpenIfChanged in class IndexReader
    
    Throws:
    
    CorruptIndexException
    
    IOException
    
    See Also:
    
    IndexReader.openIfChanged(IndexReader)
  - doOpenIfChanged
```
@Deprecated
protected IndexReader doOpenIfChanged(boolean openReadOnly)
                               throws CorruptIndexException,
                                      IOException
```
    Deprecated.
    Write support will be removed in Lucene 4.0. Use doOpenIfChanged() instead.
    
    Description copied from class: IndexReader
    
    If the index has changed since it was opened, open and return a new reader; else, return null.
    
    Overrides:
    
    doOpenIfChanged in class IndexReader
    
    Throws:
    
    UnsupportedOperationException - MultiReaders cannot support changing the readOnly flag
    
    CorruptIndexException
    
    IOException
    
    See Also:
    
    IndexReader.openIfChanged(IndexReader, boolean)
  - clone
```
public Object clone()
```
    Description copied from class: IndexReader
    
    Efficiently clones the IndexReader (sharing most internal state).
    On cloning a reader with pending changes (deletions, norms), the original reader transfers its write lock to the cloned reader. This means only the cloned reader may make further changes to the index, and commit the changes to the index on close, but the old reader still reflects all changes made up until it was cloned.
    Like IndexReader.openIfChanged(IndexReader), it's safe to make changes to either the original or the cloned reader: all shared mutable state obeys "copy on write" semantics to ensure the changes are not seen by other readers.
    
    Overrides:
    
    clone in class IndexReader
  - clone
```
@Deprecated
public IndexReader clone(boolean openReadOnly)
                  throws CorruptIndexException,
                         IOException
```
    Deprecated.
    Write support will be removed in Lucene 4.0. Use clone() instead.
    
    Description copied from class: IndexReader
    
    Clones the IndexReader and optionally changes readOnly. A readOnly reader cannot open a writeable reader.
    
    Overrides:
    
    clone in class IndexReader
    
    Throws:
    
    UnsupportedOperationException - MultiReaders cannot support changing the readOnly flag
    
    CorruptIndexException - if the index is corrupt
    
    IOException - if there is a low-level IO error
  - getTermFreqVectors
```
public TermFreqVector[] getTermFreqVectors(int n)
                                    throws IOException
```
    Description copied from class: IndexReader
    
    Return an array of term frequency vectors for the specified document. The array contains a vector for each vectorized field in the document. Each vector contains terms and frequencies for all terms in a given vectorized field. If no such fields existed, the method returns null. The term vectors that are returned may either be of type TermFreqVector or of type TermPositionVector if positions or offsets have been stored.
    
    Specified by:
    
    getTermFreqVectors in class IndexReader
    
    Parameters:
    
    n - document for which term frequency vectors are returned
    
    Returns:
    
    array of term frequency vectors. May be null if no term vectors have been stored for the specified document.
    
    Throws:
    
    IOException - if index cannot be accessed
    
    See Also:
    
    Field.TermVector
  - getTermFreqVector
```
public TermFreqVector getTermFreqVector(int n,
                                        String field)
                                 throws IOException
```
    Description copied from class: IndexReader
    
    Return a term frequency vector for the specified document and field. The returned vector contains terms and frequencies for the terms in the specified field of this document, if the field had the storeTermVector flag set. If termvectors had been stored with positions or offsets, a TermPositionVector is returned.
    
    Specified by:
    
    getTermFreqVector in class IndexReader
    
    Parameters:
    
    n - document for which the term frequency vector is returned
    
    field - field for which the term frequency vector is returned.
    
    Returns:
    
    term frequency vector May be null if field does not exist in the specified document or term vector was not stored.
    
    Throws:
    
    IOException - if index cannot be accessed
    
    See Also:
    
    Field.TermVector
  - getTermFreqVector
```
public void getTermFreqVector(int docNumber,
                              String field,
                              TermVectorMapper mapper)
                       throws IOException
```
    Description copied from class: IndexReader
    
    Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of the TermFreqVector.
    
    Specified by:
    
    getTermFreqVector in class IndexReader
    
    Parameters:
    
    docNumber - The number of the document to load the vector for
    
    field - The name of the field to load
    
    mapper - The TermVectorMapper to process the vector. Must not be null
    
    Throws:
    
    IOException - if term vectors cannot be accessed or if they do not exist on the field and doc. specified.
  - getTermFreqVector
```
public void getTermFreqVector(int docNumber,
                              TermVectorMapper mapper)
                       throws IOException
```
    Description copied from class: IndexReader
    
    Map all the term vectors for all fields in a Document
    
    Specified by:
    
    getTermFreqVector in class IndexReader
    
    Parameters:
    
    docNumber - The number of the document to load the vector for
    
    mapper - The TermVectorMapper to process the vector. Must not be null
    
    Throws:
    
    IOException - if term vectors cannot be accessed or if they do not exist on the field and doc. specified.
  - isOptimized
```
@Deprecated
public boolean isOptimized()
```
    Deprecated.
    
    Overrides:
    
    isOptimized in class IndexReader
  - numDocs
```
public int numDocs()
```
    Description copied from class: IndexReader
    
    Returns the number of documents in this index.
    
    Specified by:
    
    numDocs in class IndexReader
  - maxDoc
```
public int maxDoc()
```
    Description copied from class: IndexReader
    
    Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.
    
    Specified by:
    
    maxDoc in class IndexReader
  - document
```
public Document document(int n,
                         FieldSelector fieldSelector)
                  throws CorruptIndexException,
                         IOException
```
    Description copied from class: IndexReader
    
    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 this 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.
    NOTE: for performance reasons, this method does not check if the requested document is deleted, and therefore asking for a deleted document may yield unspecified results. Usually this is not required, however you can call IndexReader.isDeleted(int) with the requested document ID to verify the document is not deleted.
    
    Specified by:
    
    document in class IndexReader
    
    Parameters:
    
    n - 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:
    
    Fieldable, FieldSelector, SetBasedFieldSelector, LoadFirstFieldSelector
  - isDeleted
```
public boolean isDeleted(int n)
```
    Description copied from class: IndexReader
    
    Returns true if document n has been deleted
    
    Specified by:
    
    isDeleted in class IndexReader
  - hasDeletions
```
public boolean hasDeletions()
```
    Description copied from class: IndexReader
    
    Returns true if any documents have been deleted
    
    Specified by:
    
    hasDeletions in class IndexReader
  - doDelete
```
@Deprecated
protected void doDelete(int n)
                 throws CorruptIndexException,
                        IOException
```
    Deprecated.
    
    Implements deletion of the document numbered docNum. Applications should call IndexReader.deleteDocument(int) or IndexReader.deleteDocuments(Term).
    
    Specified by:
    
    doDelete in class IndexReader
    
    Throws:
    
    CorruptIndexException
    
    IOException
  - doUndeleteAll
```
@Deprecated
protected void doUndeleteAll()
                      throws CorruptIndexException,
                             IOException
```
    Deprecated.
    
    Implements actual undeleteAll() in subclass.
    
    Specified by:
    
    doUndeleteAll in class IndexReader
    
    Throws:
    
    CorruptIndexException
    
    IOException
  - readerIndex
```
protected int readerIndex(int n)
```
  - hasNorms
```
public boolean hasNorms(String field)
                 throws IOException
```
    Description copied from class: IndexReader
    
    Returns true if there are norms stored for this field.
    
    Overrides:
    
    hasNorms in class IndexReader
    
    Throws:
    
    IOException
  - norms
```
public byte[] norms(String field)
             throws IOException
```
    Description copied from class: IndexReader
    
    Returns the byte-encoded normalization factor for the named field of every document. This is used by the search code to score documents. Returns null if norms were not indexed for this field.
    
    Specified by:
    
    norms in class IndexReader
    
    Throws:
    
    IOException
    
    See Also:
    
    AbstractField.setBoost(float)
  - norms
```
public void norms(String field,
                  byte[] result,
                  int offset)
           throws IOException
```
    Description copied from class: IndexReader
    
    Reads the byte-encoded normalization factor for the named field of every document. This is used by the search code to score documents.
    
    Specified by:
    
    norms in class IndexReader
    
    Throws:
    
    IOException
    
    See Also:
    
    AbstractField.setBoost(float)
  - doSetNorm
```
@Deprecated
protected void doSetNorm(int n,
                         String field,
                         byte value)
                  throws CorruptIndexException,
                         IOException
```
    Deprecated.
    
    Implements setNorm in subclass.
    
    Specified by:
    
    doSetNorm in class IndexReader
    
    Throws:
    
    CorruptIndexException
    
    IOException
  - terms
```
public TermEnum terms()
               throws IOException
```
    Description copied from class: IndexReader
    
    Returns an enumeration of all the terms in the index. The enumeration is ordered by Term.compareTo(). Each term is greater than all that precede it in the enumeration. Note that after calling terms(), TermEnum.next() must be called on the resulting enumeration before calling other methods such as TermEnum.term().
    
    Specified by:
    
    terms in class IndexReader
    
    Throws:
    
    IOException - if there is a low-level IO error
  - terms
```
public TermEnum terms(Term term)
               throws IOException
```
    Description copied from class: IndexReader
    
    Returns an enumeration of all terms starting at a given term. If the given term does not exist, the enumeration is positioned at the first term greater than the supplied term. The enumeration is ordered by Term.compareTo(). Each term is greater than all that precede it in the enumeration.
    
    Specified by:
    
    terms in class IndexReader
    
    Throws:
    
    IOException - if there is a low-level IO error
  - docFreq
```
public int docFreq(Term t)
            throws IOException
```
    Description copied from class: IndexReader
    
    Returns the number of documents containing the term t.
    
    Specified by:
    
    docFreq in class IndexReader
    
    Throws:
    
    IOException - if there is a low-level IO error
  - termDocs
```
public TermDocs termDocs()
                  throws IOException
```
    Description copied from class: IndexReader
    
    Returns an unpositioned TermDocs enumerator.
    Note: the TermDocs returned is unpositioned. Before using it, ensure that you first position it with TermDocs.seek(Term) or TermDocs.seek(TermEnum).
    
    Specified by:
    
    termDocs in class IndexReader
    
    Throws:
    
    IOException - if there is a low-level IO error
  - termDocs
```
public TermDocs termDocs(Term term)
                  throws IOException
```
    Description copied from class: IndexReader
    Returns an enumeration of all the documents which contain term. For each document, the document number, the frequency of the term in that document is also provided, for use in search scoring. If term is null, then all non-deleted docs are returned with freq=1. Thus, this method implements the mapping:
    Term => <docNum, freq>^*
    
    The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.
    Overrides:
    
    termDocs in class IndexReader
    
    Throws:
    
    IOException - if there is a low-level IO error
  - termPositions
```
public TermPositions termPositions()
                            throws IOException
```
    Description copied from class: IndexReader
    
    Returns an unpositioned TermPositions enumerator.
    
    Specified by:
    
    termPositions in class IndexReader
    
    Throws:
    
    IOException - if there is a low-level IO error
  - doCommit
```
@Deprecated
protected void doCommit(Map<String,String> commitUserData)
                 throws IOException
```
    Deprecated.
    
    Implements commit.
    
    Specified by:
    
    doCommit in class IndexReader
    
    Throws:
    
    IOException
  - doClose
```
protected void doClose()
                throws IOException
```
    Description copied from class: IndexReader
    
    Implements close.
    
    Specified by:
    
    doClose in class IndexReader
    
    Throws:
    
    IOException
  - isCurrent
```
public boolean isCurrent()
                  throws CorruptIndexException,
                         IOException
```
    Checks recursively if all subreaders are up to date.
    
    Overrides:
    
    isCurrent in class IndexReader
    
    Throws:
    
    CorruptIndexException - if the index is corrupt
    
    IOException - if there is a low-level IO error
  - getVersion
```
public long getVersion()
```
    Not implemented.
    
    Overrides:
    
    getVersion in class IndexReader
    
    Throws:
    
    UnsupportedOperationException
  - getSequentialSubReaders
```
public IndexReader[] getSequentialSubReaders()
```
    Description copied from class: IndexReader
    
    Expert: returns the sequential sub readers that this reader is logically composed of. For example, IndexSearcher uses this API to drive searching by one sub reader at a time. If this reader is not composed of sequential child readers, it should return null. If this method returns an empty array, that means this reader is a null reader (for example a MultiReader that has no sub readers).
    NOTE: You should not try using sub-readers returned by this method to make any changes (setNorm, deleteDocument, etc.). While this might succeed for one composite reader (like MultiReader), it will most likely lead to index corruption for other readers (like DirectoryReader obtained through IndexReader.open(org.apache.lucene.store.Directory). Use the parent reader directly.
    
    Overrides:
    
    getSequentialSubReaders in class IndexReader

Modifier and Type	Field	Description
`protected int[]`	`starts`
`protected IndexReader[]`	`subReaders`

Class MultiReader

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader

Field Summary

Fields inherited from class org.apache.lucene.index.IndexReader

Constructor Summary

Method Summary

Methods inherited from class org.apache.lucene.index.IndexReader

Methods inherited from class java.lang.Object

Field Detail

subReaders

starts

Constructor Detail

MultiReader

MultiReader

Method Detail

getFieldInfos

doOpenIfChanged

doOpenIfChanged

clone

clone

getTermFreqVectors

getTermFreqVector

getTermFreqVector

getTermFreqVector

isOptimized

numDocs

maxDoc

document

isDeleted

hasDeletions

doDelete

doUndeleteAll

readerIndex

hasNorms

norms

norms

doSetNorm

terms

terms

docFreq

termDocs

termDocs

termPositions

doCommit

doClose

isCurrent

getVersion

getSequentialSubReaders