001    /*
002     * Copyright (C) 2008 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.Iterator;
022    
023    /**
024     * An iterator that does not support {@link #remove}.
025     *
026     * @author Jared Levy
027     * @since 2 (imported from Google Collections Library)
028     */
029    @GwtCompatible
030    public abstract class UnmodifiableIterator<E> implements Iterator<E> {
031      /** Constructor for use by subclasses. */
032      protected UnmodifiableIterator() {}
033      
034      /**
035       * Guaranteed to throw an exception and leave the underlying data unmodified.
036       *
037       * @throws UnsupportedOperationException always
038       */
039      @Override
040      public final void remove() {
041        throw new UnsupportedOperationException();
042      }
043    }