org.conqat.lib.commons.collections.UnmodifiableList Maven / Gradle / Ivy

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Provides common utility functions
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/*
 * Copyright (c) CQSE GmbH
 *
 * 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 org.conqat.lib.commons.collections;

import java.util.Collection;
import java.util.Collections;
import java.util.List;

import com.fasterxml.jackson.annotation.JsonIgnore;

/**
 * This is a wrapper for a {@link List} prohibiting all calls which would modify its contents. As
 * the construction of this class is performed in constant time it is preferred over copying the
 * list (which takes linear time). Using this class is also preferred to using the
 * unmodifiableX() in class {@link Collections} as they return the collection base type
 * that does not signal that the object is unmodifiable. Using the classes in this package makes
 * unmodifiability more explicit.
 * 
 * All prohibited methods throw an {@link UnsupportedOperationException}. The class is nearly the
 * same as the one returned by {@link Collections#unmodifiableList(List)}, but by making it a public
 * class we can make the return value of some methods more explicit.
 * 
 * This list is serializable if the wrapped list is serializable.
 * 
 * @author Benjamin Hummel
 */
public class UnmodifiableList extends UnmodifiableCollection implements List {

	/** Version used for serialization. */
	private static final long serialVersionUID = 1;

	/** The underlying list. */
	@JsonIgnore
	protected final List l;

	/**
	 * Creates a new unmodifiable list from another list. All modifications to the underlying list will
	 * directly be visible in this wrapper.
	 */
	public UnmodifiableList(List l) {
		super(l);
		this.l = l;
	}

	/** {@inheritDoc} */
	@Override
	public E get(int index) {
		return l.get(index);
	}

	/** {@inheritDoc} */
	@Override
	public int indexOf(Object o) {
		return l.indexOf(o);
	}

	/** {@inheritDoc} */
	@Override
	public int lastIndexOf(Object o) {
		return l.lastIndexOf(o);
	}

	/** {@inheritDoc} */
	@Override
	public UnmodifiableListIterator listIterator() {
		return new UnmodifiableListIterator<>(l.listIterator());
	}

	/** {@inheritDoc} */
	@Override
	public UnmodifiableListIterator listIterator(int index) {
		return new UnmodifiableListIterator<>(l.listIterator(index));
	}

	/** {@inheritDoc} */
	@Override
	public List subList(int fromIndex, int toIndex) {
		return new UnmodifiableList<>(l.subList(fromIndex, toIndex));
	}

	/**
	 * Operation is not supported.
	 */
	@Override
	public void add(int arg0, E arg1) {
		throw new UnsupportedOperationException();
	}

	/**
	 * Operation is not supported.
	 */
	@Override
	public boolean addAll(int arg0, Collection arg1) {
		throw new UnsupportedOperationException();
	}

	/**
	 * Operation is not supported.
	 */
	@Override
	public E remove(int arg0) {
		throw new UnsupportedOperationException();
	}

	/**
	 * Operation is not supported.
	 */
	@Override
	public E set(int arg0, E arg1) {
		throw new UnsupportedOperationException();
	}
}