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.Beta;
020    import com.google.common.annotations.GwtCompatible;
021    
022    import java.util.ListIterator;
023    
024    /**
025     * A list iterator that does not support {@link #remove}, {@link #add}, or
026     * {@link #set}.
027     *
028     * @since 7
029     * @author Louis Wasserman
030     */
031    @Beta
032    @GwtCompatible
033    public abstract class UnmodifiableListIterator<E> 
034        extends UnmodifiableIterator<E> implements ListIterator<E> {
035      /** Constructor for use by subclasses. */
036      protected UnmodifiableListIterator(){}
037      
038      /**
039       * Guaranteed to throw an exception and leave the underlying data unmodified.
040       *
041       * @throws UnsupportedOperationException always
042       */
043      @Override public final void add(E e) {
044        throw new UnsupportedOperationException();
045      }
046    
047      /**
048       * Guaranteed to throw an exception and leave the underlying data unmodified.
049       *
050       * @throws UnsupportedOperationException always
051       */
052      @Override public final void set(E e) {
053        throw new UnsupportedOperationException();
054      }
055    }