https://lucene.apache.org/lucene-parent/lucene-core: Apache Lucene Java Core (The Apache Software Foundation) 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.lucene.search;

import java.io.IOException;
import java.util.Collection;


Reports the positions and optionally offsets of all matching terms in a query for a single document To obtain a MatchesIterator for a particular field, call getMatches(String). Note that you can call getMatches(String) multiple times to retrieve new iterators, but it is not thread-safe. 
@lucene.experimental
/**
 * Reports the positions and optionally offsets of all matching terms in a query
 * for a single document
 *
 * To obtain a {@link MatchesIterator} for a particular field, call {@link #getMatches(String)}.
 * Note that you can call {@link #getMatches(String)} multiple times to retrieve new
 * iterators, but it is not thread-safe.
 *
 * @lucene.experimental
 */
public interface Matches extends Iterable<String> {

  
Returns a MatchesIterator over the matches for a single field, or null if there are no matches in that field. 
/**
   * Returns a {@link MatchesIterator} over the matches for a single field,
   * or {@code null} if there are no matches in that field.
   */
  MatchesIterator getMatches(String field) throws IOException;

  
Returns a collection of Matches that make up this instance; if it is not
a composite, then this returns an empty list

/**
   * Returns a collection of Matches that make up this instance; if it is not
   * a composite, then this returns an empty list
   */
  Collection<Matches> getSubMatches();

}