Commons Collections example source code file (AbstractEmptyIterator.java)

This example Commons Collections source code file (AbstractEmptyIterator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Collections tags/keywords

abstractemptyiterator, abstractemptyiterator, illegalstateexception, illegalstateexception, iterator, iterator, nosuchelementexception, object, object, unsupportedoperationexception, util

The Commons Collections AbstractEmptyIterator.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.commons.collections.iterators;

import java.util.NoSuchElementException;

/** 
 * Provides an implementation of an empty iterator.
 *
 * @since Commons Collections 3.1
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Stephen Colebourne
 */
abstract class AbstractEmptyIterator {
 
    /**
     * Constructor.
     */
    protected AbstractEmptyIterator() {
        super();
    }

    public boolean hasNext() {
        return false;
    }

    public Object next() {
        throw new NoSuchElementException("Iterator contains no elements");
    }

    public boolean hasPrevious() {
        return false;
    }

    public Object previous() {
        throw new NoSuchElementException("Iterator contains no elements");
    }

    public int nextIndex() {
        return 0;
    }

    public int previousIndex() {
        return -1;
    }

    public void add(Object obj) {
        throw new UnsupportedOperationException("add() not supported for empty Iterator");
    }

    public void set(Object obj) {
        throw new IllegalStateException("Iterator contains no elements");
    }

    public void remove() {
        throw new IllegalStateException("Iterator contains no elements");
    }

    public Object getKey() {
        throw new IllegalStateException("Iterator contains no elements");
    }

    public Object getValue() {
        throw new IllegalStateException("Iterator contains no elements");
    }

    public Object setValue(Object value) {
        throw new IllegalStateException("Iterator contains no elements");
    }

    public void reset() {
        // do nothing
    }

}