Fields (Lucene 9.11.1 core API)

java.lang.Object
- org.apache.lucene.index.Fields

All Implemented Interfaces:

Iterable<String>

Direct Known Subclasses:

FieldsProducer, FilterLeafReader.FilterFields, MultiFields
```
public abstract class Fields
extends Object
implements Iterable<String>
```
Provides a Terms index for fields that have it, and lists which fields do. This is primarily an internal/experimental API (see FieldsProducer), although it is also used to expose the set of term vectors per document.

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

Field Summary

Fields
Modifier and Type Field Description

static Fields[] EMPTY_ARRAY
Zero-length Fields array.

Constructor Summary

Constructors
Modifier Constructor Description

protected Fields()
Sole constructor.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`abstract Iterator<String>`	`iterator()`	Returns an iterator that will step through all fields names.
`abstract int`	`size()`	Returns the number of fields or -1 if the number of distinct field names is unknown.
`abstract Terms`	`terms(String field)`	Get the `Terms` for this field.

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

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Field Detail
  - EMPTY_ARRAY
```
public static final Fields[] EMPTY_ARRAY
```
    Zero-length Fields array.
- Constructor Detail
  - Fields
```
protected Fields()
```
    Sole constructor. (For invocation by subclass constructors, typically implicit.)
- Method Detail
  - iterator
```
public abstract Iterator<String> iterator()
```
    Returns an iterator that will step through all fields names. This will not return null.
    
    Specified by:
    
    iterator in interface Iterable<String>
  - terms
```
public abstract Terms terms(String field)
                     throws IOException
```
    Get the Terms for this field. This will return null if the field does not exist.
    
    Throws:
    
    IOException
  - size
```
public abstract int size()
```
    Returns the number of fields or -1 if the number of distinct field names is unknown. If >= 0, iterator() will return as many field names.