68 lines
2.6 KiB
Java
68 lines
2.6 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.collections4;
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import java.util.Set;
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/**
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* Defines a map that holds a set of values against each key.
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* <p>
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* A {@code SetValuedMap} is a Map with slightly different semantics:
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* </p>
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* <ul>
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* <li>Putting a value into the map will add the value to a {@link Set} at that key.</li>
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* <li>Getting a value will return a {@link Set}, holding all the values put to that key.</li>
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* </ul>
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*
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* @param <K> the type of the keys in this map
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* @param <V> the type of the values in this map
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* @since 4.1
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*/
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public interface SetValuedMap<K, V> extends MultiValuedMap<K, V> {
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/**
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* Gets the set of values associated with the specified key.
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* <p>
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* Implementations typically return an empty {@code Set} if no values
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* have been mapped to the key.
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* <p>
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*
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* @param key the key to retrieve
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* @return the {@code Set} of values, implementations should return an
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* empty {@code Set} for no mapping
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* @throws NullPointerException if the key is null and null keys are invalid
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*/
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@Override
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Set<V> get(K key);
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/**
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* Removes all values associated with the specified key.
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* <p>
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* The returned set <i>may</i> be modifiable, but updates will not be
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* propagated to this set-valued map. In case no mapping was stored for the
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* specified key, an empty, unmodifiable set will be returned.
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*
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* @param key the key to remove values from
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* @return the {@code Set} of values removed, implementations should
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* return null for no mapping found, but may return an empty collection
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* @throws UnsupportedOperationException if the map is unmodifiable
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* @throws NullPointerException if the key is null and null keys are invalid
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*/
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@Override
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Set<V> remove(Object key);
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}
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