ratpack.util.MultiValueMap Maven / Gradle / Ivy
/*
* Copyright 2013 the original author or authors.
*
* Licensed 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 ratpack.util;
import ratpack.api.Nullable;
import java.util.List;
import java.util.Map;
/**
* A map that may contain multiple values for a given key, but typically only one value.
*
* Unlike other multi map types, this type is optimized for the case where there is only one value for a key.
* The map acts just like a normal {@link Map}, but has extra methods for getting all values for a key.
*
* All implementations of this type are immutable. Mutating operations throw {@link UnsupportedOperationException}.
*
* Where there is multiple values for a given key, retrieving a single value will return the first value,
* where the first value is intrinsic to the service in which the map is being used.
*
* @param The type of key objects
* @param The type of value objects
*/
public interface MultiValueMap extends Map {
/**
* All of the values for the given key. An empty list if there are no values for the key.
*
* The returned list is immutable.
*
* @param key The key to return all values of
* @return all of the values for the given key, or an empty list if there are no values for the key.
*/
public List getAll(K key);
/**
* Returns a new view of the map where each map value is a list of all the values for the given key (i.e. a traditional multi map).
*
* The returned map is immutable.
* @return A new view of the map where each map value is a list of all the values for the given key
*/
public Map> getAll();
/**
* Get the first value for the key, or {@code null} if there are no values for the key.
*
* @param key The key to obtain the first value for
* @return The first value for the given key, or {@code null} if there are no values for the given key
*/
@Nullable
public V get(Object key);
/**
* Throws {@link UnsupportedOperationException}.
*
* {@inheritDoc}
*/
V put(K key, V value);
/**
* Throws {@link UnsupportedOperationException}.
*
* {@inheritDoc}
*/
V remove(Object key);
/**
* Throws {@link UnsupportedOperationException}.
*
* {@inheritDoc}
*/
@SuppressWarnings("NullableProblems")
void putAll(Map m);
/**
* Throws {@link UnsupportedOperationException}.
*
* {@inheritDoc}
*/
void clear();
}