## org.apache.lucene.search
Class BooleanClause.Occur

    java.lang.Object
      org.apache.lucene.util.Parameter
          org.apache.lucene.search.BooleanClause.Occur

All Implemented Interfaces:
  java.io.Serializable

Enclosing class:
  BooleanClause

    public static final class BooleanClause.Occur

extends Parameter
implements java.io.Serializable

Specifies how clauses are to occur in matching documents.

See Also:
  Serialized Form

Field Summary
`static BooleanClause.Occur` `MUST` Use this operator for clauses that must appear in the matching documents.
`static BooleanClause.Occur` `MUST_NOT` Use this operator for clauses that must not appear in the matching documents.
`static BooleanClause.Occur` `SHOULD` Use this operator for clauses that should appear in the matching documents.

Method Summary
`java.lang.String` `toString()`

Methods inherited from class org.apache.lucene.util.Parameter
`readResolve`

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

Field Detail

### MUST

    public static final BooleanClause.Occur MUST

  Use this operator for clauses that must appear in the matching documents.

### SHOULD

    public static final BooleanClause.Occur SHOULD

  Use this operator for clauses that should appear in the matching documents. For a BooleanQuery with no `MUST` clauses one or more `SHOULD` clauses must match a document for the BooleanQuery to match.

  See Also:
    `BooleanQuery.setMinimumNumberShouldMatch(int)`

### MUST_NOT

    public static final BooleanClause.Occur MUST_NOT

  Use this operator for clauses that must not appear in the matching documents. Note that it is not possible to search for queries that only consist of a `MUST_NOT` clause.

Method Detail

### toString

    public java.lang.String toString()

  Overrides:
    `toString` in class `Parameter`

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