Package org.apache.lucene.index

# Class Terms

java.lang.Object
org.apache.lucene.index.Terms

Direct Known Subclasses:
  `FieldReader`, `FilterLeafReader.FilterTerms`, `MultiTerms`

public abstract class Terms extends Object
Access to the terms in a specific field. See `Fields`.

WARNING: This API is experimental and might change in incompatible ways in the next release.

## Field Summary

Fields
Modifier and Type
Field
Description
`static final Terms[]`
`EMPTY_ARRAY`
Zero-length array of `Terms`.

## Constructor Summary

Constructors
Modifier
Constructor
Description
`protected`
`Terms()`
Sole constructor.

## Method Summary

Modifier and Type
Method
Description
`abstract int`
`getDocCount()`
Returns the number of documents that have at least one term for this field.
`BytesRef`
`getMax()`
Returns the largest term (in lexicographic order) in the field.
`BytesRef`
`getMin()`
Returns the smallest term (in lexicographic order) in the field.
`Object`
`getStats()`
Expert: returns additional information about this Terms instance for debugging purposes.
`abstract long`
`getSumDocFreq()`
Returns the sum of `TermsEnum.docFreq()` for all terms in this field.
`abstract long`
`getSumTotalTermFreq()`
Returns the sum of `TermsEnum.totalTermFreq()` for all terms in this field.
`static Terms`
`getTerms(LeafReader reader, String field)`
Returns the `Terms` index for this field, or `EMPTY` if it has none.
`abstract boolean`
`hasFreqs()`
Returns true if documents in this field store per-document term frequency (`PostingsEnum.freq()`).
`abstract boolean`
`hasOffsets()`
Returns true if documents in this field store offsets.
`abstract boolean`
`hasPayloads()`
Returns true if documents in this field store payloads.
`abstract boolean`
`hasPositions()`
Returns true if documents in this field store positions.
`TermsEnum`
`intersect(CompiledAutomaton compiled, BytesRef startTerm)`
Returns a TermsEnum that iterates over all terms and documents that are accepted by the provided `CompiledAutomaton`.
`abstract TermsEnum`
`iterator()`
Returns an iterator that will step through all terms.
`abstract long`
`size()`
Returns the number of terms for this field, or -1 if this measure isn't stored by the codec.

### Methods inherited from class java.lang.Object

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

## Field Details

### EMPTY_ARRAY

public static final Terms[] EMPTY_ARRAY
Zero-length array of `Terms`.

## Constructor Details

### Terms

protected Terms()
Sole constructor. (For invocation by subclass constructors, typically implicit.)

## Method Details

### getTerms

public static Terms getTerms(LeafReader reader, String field) throws IOException
Returns the `Terms` index for this field, or `EMPTY` if it has none.

Returns:
  terms instance, or an empty instance if `field` does not exist in this reader
Throws:
  `IOException` - if an I/O error occurs.

### iterator

public abstract TermsEnum iterator() throws IOException
Returns an iterator that will step through all terms. This method will not return null.

Throws:
  `IOException`

### intersect

public TermsEnum intersect(CompiledAutomaton compiled, BytesRef startTerm) throws IOException
Returns a TermsEnum that iterates over all terms and documents that are accepted by the provided `CompiledAutomaton`. If the `startTerm` is provided then the returned enum will only return terms `> startTerm`, but you still must call next() first to get to the first term. Note that the provided `startTerm` must be accepted by the automaton.

This is an expert low-level API and will only work for `NORMAL` compiled automata. To handle any compiled automata you should instead use `CompiledAutomaton.getTermsEnum(org.apache.lucene.index.Terms)` instead.

NOTE: the returned TermsEnum cannot seek.

Throws:
  `IOException`

### size

public abstract long size() throws IOException
Returns the number of terms for this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.

Throws:
  `IOException`

### getSumTotalTermFreq

public abstract long getSumTotalTermFreq() throws IOException
Returns the sum of `TermsEnum.totalTermFreq()` for all terms in this field. Note that, just like other term measures, this measure does not take deleted documents into account.

Throws:
  `IOException`

### getSumDocFreq

public abstract long getSumDocFreq() throws IOException
Returns the sum of `TermsEnum.docFreq()` for all terms in this field. Note that, just like other term measures, this measure does not take deleted documents into account.

Throws:
  `IOException`

### getDocCount

public abstract int getDocCount() throws IOException
Returns the number of documents that have at least one term for this field. Note that, just like other term measures, this measure does not take deleted documents into account.

Throws:
  `IOException`

### hasFreqs

public abstract boolean hasFreqs()
Returns true if documents in this field store per-document term frequency (`PostingsEnum.freq()`).

### hasOffsets

public abstract boolean hasOffsets()
Returns true if documents in this field store offsets.

### hasPositions

public abstract boolean hasPositions()
Returns true if documents in this field store positions.

### hasPayloads

public abstract boolean hasPayloads()
Returns true if documents in this field store payloads.

### getMin

public BytesRef getMin() throws IOException
Returns the smallest term (in lexicographic order) in the field. Note that, just like other term measures, this measure does not take deleted documents into account. This returns null when there are no terms.

Throws:
  `IOException`

### getMax

public BytesRef getMax() throws IOException
Returns the largest term (in lexicographic order) in the field. Note that, just like other term measures, this measure does not take deleted documents into account. This returns null when there are no terms.

Throws:
  `IOException`

### getStats

public Object getStats() throws IOException
Expert: returns additional information about this Terms instance for debugging purposes.

Throws:
  `IOException`