EmptyMap.java

/*******************************************************************************
 * Copyright (c) 2013 Stephen F. Siegel, University of Delaware.
 * 
 * This file is part of SARL.
 * 
 * SARL is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * SARL is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with SARL. If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package edu.udel.cis.vsl.sarl.util;

import java.util.Collection;
import java.util.Map;
import java.util.Set;

public class EmptyMap<K, V> implements Map<K, V> {

	@Override
	public int size() {
		return 0;
	}

	@Override
	public boolean isEmpty() {
		return true;
	}

	@Override
	public boolean containsKey(Object key) {
		return false;
	}

	@Override
	public boolean containsValue(Object value) {
		return false;
	}

	@Override
	public V get(Object key) {
		return null;
	}

	@Override
	public V put(K key, V value) {
		throw new UnsupportedOperationException("This is an immutable map");
	}

	@Override
	public V remove(Object key) {
		throw new UnsupportedOperationException("This is an immutable map");
	}

	@Override
	public void putAll(Map<? extends K, ? extends V> m) {
		throw new UnsupportedOperationException("This is an immutable map");
	}

	@Override
	public void clear() {
		throw new UnsupportedOperationException("This is an immutable map");
	}

	@Override
	public Set<K> keySet() {
		return new EmptySet<K>();
	}

	@Override
	public Collection<V> values() {
		return new EmptySet<V>();
	}

	@Override
	public Set<java.util.Map.Entry<K, V>> entrySet() {
		return new EmptySet<Entry<K, V>>();
	}
}