org.apache.lucene.document
Class Document

java.lang.Object
  org.apache.lucene.document.Document

All Implemented Interfaces:

Serializable

public final class Document
extends Object
implements Serializable

Documents are the unit of indexing and search. A Document is a set of fields. Each field has a name and a textual value. A field may be stored with the document, in which case it is returned with search hits on the document. Thus each document should typically contain one or more stored fields which uniquely identify it.

Note that fields which are not stored are not available in documents retrieved from the index, e.g. with ScoreDoc.doc, Searcher.doc(int) or IndexReader.document(int).

See Also:

Serialized Form

Constructor Summary

Document()
Constructs a new document with no fields.

Method Summary

void	add(Fieldable field) Adds a field to a document.
String	get(String name) Returns the string value of the field with the given name if any exist in this document, or null.
byte[]	getBinaryValue(String name) Returns an array of bytes for the first (or only) field that has the name specified as the method parameter.
byte[][]	getBinaryValues(String name) Returns an array of byte arrays for of the fields that have the name specified as the method parameter.
float	getBoost() Returns, at indexing time, the boost factor as set by setBoost(float).
Field	getField(String name) Returns a field with the given name if any exist in this document, or null.
Fieldable	getFieldable(String name) Returns a field with the given name if any exist in this document, or null.
Fieldable[]	getFieldables(String name) Returns an array of Fieldables with the given name.
List<Fieldable>	getFields() Returns a List of all the fields in a document.
Field[]	getFields(String name) Returns an array of Fields with the given name.
String[]	getValues(String name) Returns an array of values of the field specified as the method parameter.
void	removeField(String name) Removes field with the specified name from the document.
void	removeFields(String name) Removes all fields with the given name from the document.
void	setBoost(float boost) Sets a boost factor for hits on any field of this document.
String	toString() Prints the fields of a document for human consumption.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Document

public Document()

Constructs a new document with no fields.

Method Detail

setBoost

public void setBoost(float boost)

Sets a boost factor for hits on any field of this document. This value will be multiplied into the score of all hits on this document.

The default value is 1.0.

Values are multiplied into the value of Fieldable.getBoost() of each field in this document. Thus, this method in effect sets a default boost for the fields of this document.

See Also:

Fieldable.setBoost(float)

getBoost

public float getBoost()

Returns, at indexing time, the boost factor as set by setBoost(float).

Note that once a document is indexed this value is no longer available from the index. At search time, for retrieved documents, this method always returns 1. This however does not mean that the boost value set at indexing time was ignored - it was just combined with other indexing time factors and stored elsewhere, for better indexing and search performance. (For more information see the "norm(t,d)" part of the scoring formula in Similarity.)

See Also:

setBoost(float)

add

public final void add(Fieldable field)

Adds a field to a document. Several fields may be added with the same name. In this case, if the fields are indexed, their text is treated as though appended for the purposes of search.

Note that add like the removeField(s) methods only makes sense prior to adding a document to an index. These methods cannot be used to change the content of an existing index! In order to achieve this, a document has to be deleted from an index and a new changed version of that document has to be added.

removeField

public final void removeField(String name)

Removes field with the specified name from the document. If multiple fields exist with this name, this method removes the first field that has been added. If there is no field with the specified name, the document remains unchanged.

Note that the removeField(s) methods like the add method only make sense prior to adding a document to an index. These methods cannot be used to change the content of an existing index! In order to achieve this, a document has to be deleted from an index and a new changed version of that document has to be added.

removeFields

public final void removeFields(String name)

Removes all fields with the given name from the document. If there is no field with the specified name, the document remains unchanged.

Note that the removeField(s) methods like the add method only make sense prior to adding a document to an index. These methods cannot be used to change the content of an existing index! In order to achieve this, a document has to be deleted from an index and a new changed version of that document has to be added.

getField

public final Field getField(String name)

Returns a field with the given name if any exist in this document, or null. If multiple fields exists with this name, this method returns the first value added. Do not use this method with lazy loaded fields.

getFieldable

public Fieldable getFieldable(String name)

Returns a field with the given name if any exist in this document, or null. If multiple fields exists with this name, this method returns the first value added.

get

public final String get(String name)

Returns the string value of the field with the given name if any exist in this document, or null. If multiple fields exist with this name, this method returns the first value added. If only binary fields with this name exist, returns null.

getFields

public final List<Fieldable> getFields()

Returns a List of all the fields in a document.

Note that fields which are not stored are not available in documents retrieved from the index, e.g. Searcher.doc(int) or IndexReader.document(int).

getFields

public final Field[] getFields(String name)

Returns an array of Fields with the given name. Do not use with lazy loaded fields. This method returns an empty array when there are no matching fields. It never returns null.

Parameters:

name - the name of the field

Returns:

a Field[] array

getFieldables

public Fieldable[] getFieldables(String name)

Returns an array of Fieldables with the given name. This method returns an empty array when there are no matching fields. It never returns null.

Parameters:

name - the name of the field

Returns:

a Fieldable[] array

getValues

public final String[] getValues(String name)

Returns an array of values of the field specified as the method parameter. This method returns an empty array when there are no matching fields. It never returns null.

Parameters:

name - the name of the field

Returns:

a String[] of field values

getBinaryValues

public final byte[][] getBinaryValues(String name)

Returns an array of byte arrays for of the fields that have the name specified as the method parameter. This method returns an empty array when there are no matching fields. It never returns null.

Parameters:

name - the name of the field

Returns:

a byte[][] of binary field values

getBinaryValue

public final byte[] getBinaryValue(String name)

Returns an array of bytes for the first (or only) field that has the name specified as the method parameter. This method will return null if no binary fields with the specified name are available. There may be non-binary fields with the same name.

Parameters:

name - the name of the field.

Returns:

a byte[] containing the binary field value or null

toString

public final String toString()

Prints the fields of a document for human consumption.

Overrides:

toString in class Object