org.apache.lucene.search

## Class PrefixQuery

- java.lang.Object
- - org.apache.lucene.search.Query
  - - org.apache.lucene.search.MultiTermQuery
    - - org.apache.lucene.search.AutomatonQuery
      - - org.apache.lucene.search.PrefixQuery

-     public class PrefixQuery
      extends AutomatonQuery

  A Query that matches documents containing terms with a specified prefix. A PrefixQuery is built by QueryParser for input like `app*`.

  This query uses the `MultiTermQuery.CONSTANT_SCORE_REWRITE` rewrite method.

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class org.apache.lucene.search.MultiTermQuery

      `MultiTermQuery.RewriteMethod, MultiTermQuery.TopTermsBlendedFreqScoringRewrite, MultiTermQuery.TopTermsBoostOnlyBooleanQueryRewrite, MultiTermQuery.TopTermsScoringBooleanQueryRewrite`

  - ### Field Summary

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

      `automaton, compiled, term`

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

      `CONSTANT_SCORE_BOOLEAN_REWRITE, CONSTANT_SCORE_REWRITE, field, rewriteMethod, SCORING_BOOLEAN_REWRITE`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `PrefixQuery(Term prefix)` Constructs a query for terms starting with `prefix`.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `equals(Object obj)` Override and implement query instance equivalence properly in a subclass.
    `Term` | `getPrefix()` Returns the prefix of this query.
    `int` | `hashCode()` Override and implement query hash code properly in a subclass.
    `static Automaton` | `toAutomaton(BytesRef prefix)` Build an automaton accepting all terms with the specified prefix.
    `String` | `toString(String field)` Prints a user-readable version of this query.

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

      `getAutomaton, getTermsEnum`

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

      `getField, getRewriteMethod, getTermsEnum, rewrite, setRewriteMethod`

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

      `classHash, createWeight, sameClassAs, toString`

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

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### PrefixQuery

          public PrefixQuery(Term prefix)

      Constructs a query for terms starting with `prefix`.

  - ### Method Detail

    - #### toAutomaton

          public static Automaton toAutomaton(BytesRef prefix)

      Build an automaton accepting all terms with the specified prefix.

    - #### getPrefix

          public Term getPrefix()

      Returns the prefix of this query.

    - #### toString

          public String toString(String field)

      Prints a user-readable version of this query.
      Overrides:
        `toString` in class `AutomatonQuery`

    - #### hashCode

          public int hashCode()

      Description copied from class: `Query`
      Override and implement query hash code properly in a subclass. This is required so that `QueryCache` works properly.
      Overrides:
        `hashCode` in class `AutomatonQuery`
      See Also:
        `Query.equals(Object)`

    - #### equals

          public boolean equals(Object obj)

      Description copied from class: `Query`
      Override and implement query instance equivalence properly in a subclass. This is required so that `QueryCache` works properly. Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.
      Overrides:
        `equals` in class `AutomatonQuery`
      See Also:
        `Query.sameClassAs(Object)`, `Query.classHash()`

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