Package org.apache.lucene.index

# Class DocsWithFieldSet

java.lang.Object
org.apache.lucene.search.DocIdSet
org.apache.lucene.index.DocsWithFieldSet

All Implemented Interfaces:
  `Accountable`

public final class DocsWithFieldSet extends DocIdSet
Accumulator for documents that have a value for a field. This is optimized for the case that all documents have a value.

## Field Summary

### Fields inherited from class org.apache.lucene.search.DocIdSet

`EMPTY`

### Fields inherited from interface org.apache.lucene.util.Accountable

`NULL_ACCOUNTABLE`

## Constructor Summary

Constructors
Constructor
Description
`DocsWithFieldSet()`
Creates an empty DocsWithFieldSet.

## Method Summary

Modifier and Type
Method
Description
`void`
`add(int docID)`
Add a document to the set
`int`
`cardinality()`
Return the number of documents of this set.
`DocIdSetIterator`
`iterator()`
Provides a `DocIdSetIterator` to access the set.
`long`
`ramBytesUsed()`
Return the memory usage of this object in bytes.

### Methods inherited from class org.apache.lucene.search.DocIdSet

`all, bits`

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

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

### Methods inherited from interface org.apache.lucene.util.Accountable

`getChildResources`

## Constructor Details

### DocsWithFieldSet

public DocsWithFieldSet()
Creates an empty DocsWithFieldSet.

## Method Details

### add

public void add(int docID)
Add a document to the set

Parameters:
  `docID` - – document ID to be added

### ramBytesUsed

public long ramBytesUsed()
Description copied from interface: `Accountable`
Return the memory usage of this object in bytes. Negative values are illegal.

### iterator

public DocIdSetIterator iterator()
Description copied from class: `DocIdSet`
Provides a `DocIdSetIterator` to access the set. This implementation can return `null` if there are no docs that match.

Specified by:
  `iterator` in class `DocIdSet`

### cardinality

public int cardinality()
Return the number of documents of this set.