org.apache.lucene.document

Class Field

public final class Field extends Object implements Serializable

A field is a section of a Document. Each field has two parts, a name and a value. Values may be free text, provided as a String or as a Reader, or they may be atomic keywords, which are not further processed. Such keywords may be used to represent dates, urls, etc. Fields are optionally stored in the index, so that they may be returned with hits on the document.
Constructor Summary
Field(String name, String string, boolean store, boolean index, boolean token)
Create a field by specifying all parameters except for storeTermVector, which is set to false.
Field(String name, String string, boolean store, boolean index, boolean token, boolean storeTermVector)
Method Summary
floatgetBoost()
Returns the boost factor for hits on any field of this document.
booleanisIndexed()
True iff the value of the field is to be indexed, so that it may be searched on.
booleanisStored()
True iff the value of the field is to be stored in the index for return with search hits.
booleanisTermVectorStored()
True iff the term or terms used to index this field are stored as a term vector, available from {@link IndexReader#getTermFreqVector(int,String)}.
booleanisTokenized()
True iff the value of the field should be tokenized as text prior to indexing.
static FieldKeyword(String name, String value)
Constructs a String-valued Field that is not tokenized, but is indexed and stored.
static FieldKeyword(String name, Date value)
Constructs a Date-valued Field that is not tokenized and is indexed, and stored in the index, for return with hits.
Stringname()
The name of the field (e.g., "date", "subject", "title", or "body") as an interned string.
ReaderreaderValue()
The value of the field as a Reader, or null.
voidsetBoost(float boost)
Sets the boost factor hits on this field.
StringstringValue()
The value of the field as a String, or null.
StringtoString()
Prints a Field for human consumption.
static FieldText(String name, String value)
Constructs a String-valued Field that is tokenized and indexed, and is stored in the index, for return with hits.
static FieldText(String name, String value, boolean storeTermVector)
Constructs a String-valued Field that is tokenized and indexed, and is stored in the index, for return with hits.
static FieldText(String name, Reader value)
Constructs a Reader-valued Field that is tokenized and indexed, but is not stored in the index verbatim.
static FieldText(String name, Reader value, boolean storeTermVector)
Constructs a Reader-valued Field that is tokenized and indexed, but is not stored in the index verbatim.
static FieldUnIndexed(String name, String value)
Constructs a String-valued Field that is not tokenized nor indexed, but is stored in the index, for return with hits.
static FieldUnStored(String name, String value)
Constructs a String-valued Field that is tokenized and indexed, but that is not stored in the index.
static FieldUnStored(String name, String value, boolean storeTermVector)
Constructs a String-valued Field that is tokenized and indexed, but that is not stored in the index.

Constructor Detail

Field

public Field(String name, String string, boolean store, boolean index, boolean token)
Create a field by specifying all parameters except for storeTermVector, which is set to false.

Field

public Field(String name, String string, boolean store, boolean index, boolean token, boolean storeTermVector)

Parameters: name The name of the field string The string to process store true if the field should store the string index true if the field should be indexed token true if the field should be tokenized storeTermVector true if we should store the Term Vector info

Method Detail

getBoost

public float getBoost()
Returns the boost factor for hits on any field of this document.

The default value is 1.0.

Note: this value is not stored directly with the document in the index. Documents returned from {@link IndexReader#document(int)} and {@link Hits#doc(int)} may thus not have the same value present as when this field was indexed.

See Also: Field

isIndexed

public final boolean isIndexed()
True iff the value of the field is to be indexed, so that it may be searched on.

isStored

public final boolean isStored()
True iff the value of the field is to be stored in the index for return with search hits. It is an error for this to be true if a field is Reader-valued.

isTermVectorStored

public final boolean isTermVectorStored()
True iff the term or terms used to index this field are stored as a term vector, available from {@link IndexReader#getTermFreqVector(int,String)}. These methods do not provide access to the original content of the field, only to terms used to index it. If the original content must be preserved, use the stored attribute instead.

See Also: IndexReader

isTokenized

public final boolean isTokenized()
True iff the value of the field should be tokenized as text prior to indexing. Un-tokenized fields are indexed as a single word and may not be Reader-valued.

Keyword

public static final Field Keyword(String name, String value)
Constructs a String-valued Field that is not tokenized, but is indexed and stored. Useful for non-text fields, e.g. date or url.

Keyword

public static final Field Keyword(String name, Date value)
Constructs a Date-valued Field that is not tokenized and is indexed, and stored in the index, for return with hits.

name

public String name()
The name of the field (e.g., "date", "subject", "title", or "body") as an interned string.

readerValue

public Reader readerValue()
The value of the field as a Reader, or null. If null, the String value is used. Exactly one of stringValue() and readerValue() must be set.

setBoost

public void setBoost(float boost)
Sets the boost factor hits on this field. This value will be multiplied into the score of all hits on this this field of this document.

The boost is multiplied by {@link Document#getBoost()} of the document containing this field. If a document has multiple fields with the same name, all such values are multiplied together. This product is then multipled by the value {@link Similarity#lengthNorm(String,int)}, and rounded by {@link Similarity#encodeNorm(float)} before it is stored in the index. One should attempt to ensure that this product does not overflow the range of that encoding.

See Also: Document Similarity Similarity

stringValue

public String stringValue()
The value of the field as a String, or null. If null, the Reader value is used. Exactly one of stringValue() and readerValue() must be set.

toString

public final String toString()
Prints a Field for human consumption.

Text

public static final Field Text(String name, String value)
Constructs a String-valued Field that is tokenized and indexed, and is stored in the index, for return with hits. Useful for short text fields, like "title" or "subject". Term vector will not be stored for this field.

Text

public static final Field Text(String name, String value, boolean storeTermVector)
Constructs a String-valued Field that is tokenized and indexed, and is stored in the index, for return with hits. Useful for short text fields, like "title" or "subject".

Text

public static final Field Text(String name, Reader value)
Constructs a Reader-valued Field that is tokenized and indexed, but is not stored in the index verbatim. Useful for longer text fields, like "body". Term vector will not be stored for this field.

Text

public static final Field Text(String name, Reader value, boolean storeTermVector)
Constructs a Reader-valued Field that is tokenized and indexed, but is not stored in the index verbatim. Useful for longer text fields, like "body".

UnIndexed

public static final Field UnIndexed(String name, String value)
Constructs a String-valued Field that is not tokenized nor indexed, but is stored in the index, for return with hits.

UnStored

public static final Field UnStored(String name, String value)
Constructs a String-valued Field that is tokenized and indexed, but that is not stored in the index. Term vector will not be stored for this field.

UnStored

public static final Field UnStored(String name, String value, boolean storeTermVector)
Constructs a String-valued Field that is tokenized and indexed, but that is not stored in the index.
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