alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (ForwardingList.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, beta, canignorereturnvalue, collection, forwardingcollection, forwardinglist, gwtcompatible, iterable, listiterator, object, override, util

The ForwardingList.java Java example source code

/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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.google.common.collect;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

import javax.annotation.Nullable;

/**
 * A list which forwards all its method calls to another list. Subclasses should
 * override one or more methods to modify the behavior of the backing list as
 * desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>This class does not implement {@link java.util.RandomAccess}. If the
 * delegate supports random access, the {@code ForwardingList} subclass should
 * implement the {@code RandomAccess} interface.
 *
 * <p>Warning: The methods of {@code ForwardingList} forward
 * <b>indiscriminately to the methods of the delegate. For example,
 * overriding {@link #add} alone <b>will not change the behavior of {@link
 * #addAll}, which can lead to unexpected behavior. In this case, you should
 * override {@code addAll} as well, either providing your own implementation, or
 * delegating to the provided {@code standardAddAll} method.
 *
 * <p>{@code default} method warning: This class does not forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingList}.
 *
 * <p>The {@code standard} methods and any collection views they return are not
 * guaranteed to be thread-safe, even when all of the methods that they depend
 * on are thread-safe.
 *
 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingList<E> extends ForwardingCollection implements List {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingList() {}

  @Override
  protected abstract List<E> delegate();

  @Override
  public void add(int index, E element) {
    delegate().add(index, element);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean addAll(int index, Collection<? extends E> elements) {
    return delegate().addAll(index, elements);
  }

  @Override
  public E get(int index) {
    return delegate().get(index);
  }

  @Override
  public int indexOf(Object element) {
    return delegate().indexOf(element);
  }

  @Override
  public int lastIndexOf(Object element) {
    return delegate().lastIndexOf(element);
  }

  @Override
  public ListIterator<E> listIterator() {
    return delegate().listIterator();
  }

  @Override
  public ListIterator<E> listIterator(int index) {
    return delegate().listIterator(index);
  }

  @CanIgnoreReturnValue
  @Override
  public E remove(int index) {
    return delegate().remove(index);
  }

  @CanIgnoreReturnValue
  @Override
  public E set(int index, E element) {
    return delegate().set(index, element);
  }

  @Override
  public List<E> subList(int fromIndex, int toIndex) {
    return delegate().subList(fromIndex, toIndex);
  }

  @Override
  public boolean equals(@Nullable Object object) {
    return object == this || delegate().equals(object);
  }

  @Override
  public int hashCode() {
    return delegate().hashCode();
  }

  /**
   * A sensible default implementation of {@link #add(Object)}, in terms of
   * {@link #add(int, Object)}. If you override {@link #add(int, Object)}, you
   * may wish to override {@link #add(Object)} to forward to this
   * implementation.
   *
   * @since 7.0
   */
  protected boolean standardAdd(E element) {
    add(size(), element);
    return true;
  }

  /**
   * A sensible default implementation of {@link #addAll(int, Collection)}, in
   * terms of the {@code add} method of {@link #listIterator(int)}. If you
   * override {@link #listIterator(int)}, you may wish to override {@link
   * #addAll(int, Collection)} to forward to this implementation.
   *
   * @since 7.0
   */
  protected boolean standardAddAll(int index, Iterable<? extends E> elements) {
    return Lists.addAllImpl(this, index, elements);
  }

  /**
   * A sensible default implementation of {@link #indexOf}, in terms of {@link
   * #listIterator()}. If you override {@link #listIterator()}, you may wish to
   * override {@link #indexOf} to forward to this implementation.
   *
   * @since 7.0
   */
  protected int standardIndexOf(@Nullable Object element) {
    return Lists.indexOfImpl(this, element);
  }

  /**
   * A sensible default implementation of {@link #lastIndexOf}, in terms of
   * {@link #listIterator(int)}. If you override {@link #listIterator(int)}, you
   * may wish to override {@link #lastIndexOf} to forward to this
   * implementation.
   *
   * @since 7.0
   */
  protected int standardLastIndexOf(@Nullable Object element) {
    return Lists.lastIndexOfImpl(this, element);
  }

  /**
   * A sensible default implementation of {@link #iterator}, in terms of
   * {@link #listIterator()}. If you override {@link #listIterator()}, you may
   * wish to override {@link #iterator} to forward to this implementation.
   *
   * @since 7.0
   */
  protected Iterator<E> standardIterator() {
    return listIterator();
  }

  /**
   * A sensible default implementation of {@link #listIterator()}, in terms of
   * {@link #listIterator(int)}. If you override {@link #listIterator(int)}, you
   * may wish to override {@link #listIterator()} to forward to this
   * implementation.
   *
   * @since 7.0
   */
  protected ListIterator<E> standardListIterator() {
    return listIterator(0);
  }

  /**
   * A sensible default implementation of {@link #listIterator(int)}, in terms
   * of {@link #size}, {@link #get(int)}, {@link #set(int, Object)}, {@link
   * #add(int, Object)}, and {@link #remove(int)}. If you override any of these
   * methods, you may wish to override {@link #listIterator(int)} to forward to
   * this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected ListIterator<E> standardListIterator(int start) {
    return Lists.listIteratorImpl(this, start);
  }

  /**
   * A sensible default implementation of {@link #subList(int, int)}. If you
   * override any other methods, you may wish to override {@link #subList(int,
   * int)} to forward to this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected List<E> standardSubList(int fromIndex, int toIndex) {
    return Lists.subListImpl(this, fromIndex, toIndex);
  }

  /**
   * A sensible definition of {@link #equals(Object)} in terms of {@link #size}
   * and {@link #iterator}. If you override either of those methods, you may
   * wish to override {@link #equals(Object)} to forward to this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected boolean standardEquals(@Nullable Object object) {
    return Lists.equalsImpl(this, object);
  }

  /**
   * A sensible definition of {@link #hashCode} in terms of {@link #iterator}.
   * If you override {@link #iterator}, you may wish to override {@link
   * #hashCode} to forward to this implementation.
   *
   * @since 7.0
   */
  @Beta
  protected int standardHashCode() {
    return Lists.hashCodeImpl(this);
  }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java ForwardingList.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.