com.rapiddweller.common.iterator.BidirectionalListIterator Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of rd-lib-common Show documentation

'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

There is a newer version: 2.0.1-jdk-11

Show newest version

/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * Licensed 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 com.rapiddweller.common.iterator;

import java.util.List;

/**
 * A {@link BidirectionalIterator} for {@link List}s.
 * Created: 08.05.2007 19:50:20
 *
 * @param  the type to iterate
 * @author Volker Bergmann
 */
public class BidirectionalListIterator implements BidirectionalIterator {

  private final List list;
  private int index;

  /**
   * Instantiates a new Bidirectional list iterator.
   *
   * @param list the list
   */
  public BidirectionalListIterator(List list) {
    this.list = list;
    this.index = -1;
  }

  @Override
  public E first() {
    index = 0;
    return list.get(index);
  }

  @Override
  public boolean hasPrevious() {
    return (index > 0);
  }

  @Override
  public E previous() {
    if (!hasPrevious()) {
      throw new IllegalStateException("No previous object exists");
    }
    index--;
    return list.get(index);
  }

  @Override
  public E last() {
    index = list.size() - 1;
    return list.get(index);
  }

  @Override
  public boolean hasNext() {
    return (index < list.size() - 1);
  }

  @Override
  public E next() {
    if (!hasNext()) {
      throw new IllegalStateException("No next object exists");
    }
    index++;
    return list.get(index);
  }

  @Override
  public void remove() {
    throw new UnsupportedOperationException("Not implemented");
  }

}