/*

 * 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.commons.collections4;

import java.util.Collection;

import java.util.Set;

/**

 * The "read" subset of the {@link java.util.Map} interface.

 *

 * @param <K> the type of the keys in this map

 * @param <V> the type of the values in this map

 *

 * @since 4.0

 * @see Put

 */

public interface Get<K, V> {

    /**

     * @param key key whose presence in this map is to be tested

     * @return <code>true</code> if this map contains a mapping for the specified

     *         key

     * @see java.util.Map#containsKey(Object)

     */

    boolean containsKey(Object key);

    /**

     * @param value value whose presence in this map is to be tested

     * @return <code>true</code> if this map maps one or more keys to the

     *         specified value

     * @see java.util.Map#containsValue(Object)

     */

    boolean containsValue(Object value);

    /**

     * @return a set view of the mappings contained in this map

     * @see java.util.Map#entrySet()

     */

    Set<java.util.Map.Entry<K, V>> entrySet();

    /**

     * @param key the key whose associated value is to be returned

     * @return the value to which the specified key is mapped, or

     *         {@code null} if this map contains no mapping for the key

     * @see java.util.Map#get(Object)

     */

    V get(Object key);

    /**

     * @param key key whose mapping is to be removed from the map

     * @return the previous value associated with <code>key</code>, or

     *         <code>null</code> if there was no mapping for <code>key</code>.

     * @see java.util.Map#remove(Object)

     */

    V remove(Object key);

    /**

     * @return <code>true</code> if this map contains no key-value mappings

     * @see java.util.Map#isEmpty()

     */

    boolean isEmpty();

    /**

     * @return a set view of the keys contained in this map

     * @see java.util.Map#keySet()

     */

    Set<K> keySet();

    /**

     * @return the number of key-value mappings in this map

     * @see java.util.Map#size()

     */

    int size();

    /**

     * @return a collection view of the values contained in this map

     * @see java.util.Map#values()

     */

    Collection<V> values();

}