org.apache.lucene.index

## Class PostingsEnum

- java.lang.Object
- - org.apache.lucene.search.DocIdSetIterator
  - - org.apache.lucene.index.PostingsEnum

- Direct Known Subclasses:
    FilterLeafReader.FilterPostingsEnum, ImpactsEnum, MultiPostingsEnum

      public abstract class PostingsEnum
      extends DocIdSetIterator

  Iterates through the postings. NOTE: you must first call `DocIdSetIterator.nextDoc()` before using any of the per-doc methods.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static short` | `ALL` Flag to pass to `TermsEnum.postings(PostingsEnum, int)` to get positions, payloads and offsets in the returned enum
    `static short` | `FREQS` Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require term frequencies in the returned enum.
    `static short` | `NONE` Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you don't require per-document postings in the returned enum.
    `static short` | `OFFSETS` Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require offsets in the returned enum.
    `static short` | `PAYLOADS` Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require payloads in the returned enum.
    `static short` | `POSITIONS` Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require term positions in the returned enum.

    - ### Fields inherited from class org.apache.lucene.search.DocIdSetIterator

      `NO_MORE_DOCS`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `PostingsEnum()` Sole constructor.

  - ### Method Summary

    All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract int` | `endOffset()` Returns end offset for the current position, or -1 if offsets were not indexed.
    `static boolean` | `featureRequested(int flags, short feature)` Returns true if the given feature is requested in the flags, false otherwise.
    `abstract int` | `freq()` Returns term frequency in the current document, or 1 if the field was indexed with `IndexOptions.DOCS`.
    `abstract BytesRef` | `getPayload()` Returns the payload at this position, or null if no payload was indexed.
    `abstract int` | `nextPosition()` Returns the next position, or -1 if positions were not indexed.
    `abstract int` | `startOffset()` Returns start offset for the current position, or -1 if offsets were not indexed.

    - ### Methods inherited from class org.apache.lucene.search.DocIdSetIterator

      `advance, all, cost, docID, empty, nextDoc, range, slowAdvance`

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

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

- - ### Field Detail

    - #### NONE

          public static final short NONE

      Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you don't require per-document postings in the returned enum.
      See Also:
        Constant Field Values

    - #### FREQS

          public static final short FREQS

      Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require term frequencies in the returned enum.
      See Also:
        Constant Field Values

    - #### POSITIONS

          public static final short POSITIONS

      Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require term positions in the returned enum.
      See Also:
        Constant Field Values

    - #### OFFSETS

          public static final short OFFSETS

      Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require offsets in the returned enum.
      See Also:
        Constant Field Values

    - #### PAYLOADS

          public static final short PAYLOADS

      Flag to pass to `TermsEnum.postings(PostingsEnum, int)` if you require payloads in the returned enum.
      See Also:
        Constant Field Values

    - #### ALL

          public static final short ALL

      Flag to pass to `TermsEnum.postings(PostingsEnum, int)` to get positions, payloads and offsets in the returned enum
      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### PostingsEnum

          protected PostingsEnum()

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

  - ### Method Detail

    - #### featureRequested

          public static boolean featureRequested(int flags,
                                                 short feature)

      Returns true if the given feature is requested in the flags, false otherwise.

    - #### freq

          public abstract int freq()
                            throws IOException

      Returns term frequency in the current document, or 1 if the field was indexed with `IndexOptions.DOCS`. Do not call this before `DocIdSetIterator.nextDoc()` is first called, nor after `DocIdSetIterator.nextDoc()` returns `DocIdSetIterator.NO_MORE_DOCS`.

      NOTE: if the `PostingsEnum` was obtain with `NONE`, the result of this method is undefined.

      Throws:
        `IOException`

    - #### nextPosition

          public abstract int nextPosition()
                                    throws IOException

      Returns the next position, or -1 if positions were not indexed. Calling this more than `freq()` times is undefined.
      Throws:
        `IOException`

    - #### startOffset

          public abstract int startOffset()
                                   throws IOException

      Returns start offset for the current position, or -1 if offsets were not indexed.
      Throws:
        `IOException`

    - #### endOffset

          public abstract int endOffset()
                                 throws IOException

      Returns end offset for the current position, or -1 if offsets were not indexed.
      Throws:
        `IOException`

    - #### getPayload

          public abstract BytesRef getPayload()
                                       throws IOException

      Returns the payload at this position, or null if no payload was indexed. You should not modify anything (neither members of the returned BytesRef nor bytes in the byte[]).
      Throws:
        `IOException`

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