org.apache.lucene.search

## Class BoostQuery

- java.lang.Object
- - org.apache.lucene.search.Query
  - - org.apache.lucene.search.BoostQuery

-     public final class BoostQuery
      extends Query

  A `Query` wrapper that allows to give a boost to the wrapped query. Boost values that are less than one will give less importance to this query compared to other ones while values that are greater than one will give more importance to the scores returned by this query. More complex boosts can be applied by using FunctionScoreQuery in the lucene-queries module

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `BoostQuery(Query query, float boost)` Sole constructor: wrap `query` in such a way that the produced scores will be boosted by `boost`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Weight` | `createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost)` Expert: Constructs an appropriate Weight implementation for this query.
    `boolean` | `equals(Object other)` Override and implement query instance equivalence properly in a subclass.
    `float` | `getBoost()` Return the applied boost.
    `Query` | `getQuery()` Return the wrapped `Query`.
    `int` | `hashCode()` Override and implement query hash code properly in a subclass.
    `Query` | `rewrite(IndexReader reader)` Expert: called to re-write queries into primitive queries.
    `String` | `toString(String field)` Prints a query to a string, with `field` assumed to be the default field and omitted.
    `void` | `visit(QueryVisitor visitor)` Recurse through the query tree, visiting any child queries

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

      `classHash, sameClassAs, toString`

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

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

- - ### Constructor Detail

    - #### BoostQuery

          public BoostQuery(Query query,
                            float boost)

      Sole constructor: wrap `query` in such a way that the produced scores will be boosted by `boost`.

  - ### Method Detail

    - #### getQuery

          public Query getQuery()

      Return the wrapped `Query`.

    - #### getBoost

          public float getBoost()

      Return the applied boost.

    - #### equals

          public boolean equals(Object other)

      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.
      Specified by:
        `equals` in class `Query`
      See Also:
        `Query.sameClassAs(Object)`, `Query.classHash()`

    - #### 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.
      Specified by:
        `hashCode` in class `Query`
      See Also:
        `Query.equals(Object)`

    - #### rewrite

          public Query rewrite(IndexReader reader)
                        throws IOException

      Description copied from class: `Query`
      Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.

      Callers are expected to call `rewrite` multiple times if necessary, until the rewritten query is the same as the original query.

      Overrides:
        `rewrite` in class `Query`
      Throws:
        `IOException`
      See Also:
        `IndexSearcher.rewrite(Query)`

    - #### visit

          public void visit(QueryVisitor visitor)

      Description copied from class: `Query`
      Recurse through the query tree, visiting any child queries
      Overrides:
        `visit` in class `Query`
      Parameters:
        `visitor` - a QueryVisitor to be called by each query in the tree

    - #### toString

          public String toString(String field)

      Description copied from class: `Query`
      Prints a query to a string, with `field` assumed to be the default field and omitted.
      Specified by:
        `toString` in class `Query`

    - #### createWeight

          public Weight createWeight(IndexSearcher searcher,
                                     ScoreMode scoreMode,
                                     float boost)
                              throws IOException

      Description copied from class: `Query`
      Expert: Constructs an appropriate Weight implementation for this query.

      Only implemented by primitive queries, which re-write to themselves.

      Overrides:
        `createWeight` in class `Query`
        `scoreMode` - How the produced scorers will be consumed.
        `boost` - The boost that is propagated by the parent queries.
      Throws:
        `IOException`

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