SequenceIterator.java :  » Science » Cougaar12_4 » org » cougaar » logistics » plugin » seanet » Java Open Source

/*
 * <copyright>
 *  
 *  Copyright 2003-2004 BBNT Solutions, LLC
 *  under sponsorship of the Defense Advanced Research Projects
 *  Agency (DARPA).
 * 
 *  You can redistribute this software and/or modify it under the
 *  terms of the Cougaar Open Source License as published on the
 *  Cougaar Open Source Website (www.cougaar.org).
 * 
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *  
 * </copyright>
 */
package org.cougaar.logistics.plugin.seanet;

import java.util.Iterator;

/**
 * A <code>SequenceIterator</code> iterates over the elements of two
 * iterators in sequence.
 *
 * @see Iterator */
public class SequenceIterator implements Iterator {
  Iterator a;
  Iterator b;

  public SequenceIterator(Iterator a, Iterator b) {
    this.a = a;
    this.b = b;
  }
  public boolean hasNext() {
    if (a.hasNext()) {
      return true;
    } 
    else if (b != null) {
      a = b;
      b = null;
      return this.hasNext();
    }
    else {
      return false;
    }
  }
  
  public Object next() {
    if (this.hasNext()) {
      return a.next();
    } else {
      throw new java.util.NoSuchElementException();
    }
  }

  public void remove() {
    throw new UnsupportedOperationException();
  }
}