    001    /*
    002     * Copyright (C) 2010 The Guava Authors
    003     *
    004     * Licensed under the Apache License, Version 2.0 (the "License");
    005     * you may not use this file except in compliance with the License.
    006     * You may obtain a copy of the License at
    007     *
    008     * http://www.apache.org/licenses/LICENSE-2.0
    009     *
    010     * Unless required by applicable law or agreed to in writing, software
    011     * distributed under the License is distributed on an "AS IS" BASIS,
    012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    013     * See the License for the specific language governing permissions and
    014     * limitations under the License.
    015     */
    016
    017    package com.google.common.collect;
    018
    019    import com.google.common.annotations.GwtCompatible;
    020
    021    import java.util.ListIterator;
    022
    023    /**
    024     * A list iterator that does not support {@link #remove}, {@link #add}, or
    025     * {@link #set}.
    026     *
    027     * @since 7.0
    028     * @author Louis Wasserman
    029     */
    030    @GwtCompatible
    031    public abstract class UnmodifiableListIterator<E>
    032        extends UnmodifiableIterator<E> implements ListIterator<E> {
    033      /** Constructor for use by subclasses. */
    034      protected UnmodifiableListIterator() {}
    035
    036      /**
    037       * Guaranteed to throw an exception and leave the underlying data unmodified.
    038       *
    039       * @throws UnsupportedOperationException always
    040       */
    041      @Override public final void add(E e) {
    042        throw new UnsupportedOperationException();
    043      }
    044
    045      /**
    046       * Guaranteed to throw an exception and leave the underlying data unmodified.
    047       *
    048       * @throws UnsupportedOperationException always
    049       */
    050      @Override public final void set(E e) {
    051        throw new UnsupportedOperationException();
    052      }
    053    }