Java example source code file (ForwardingSortedSet.java)

This example Java source code file (ForwardingSortedSet.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, classcastexception, comparable, comparator, forwardingset, forwardingsortedset, gwtcompatible, nosuchelementexception, nullpointerexception, object, override, sortedset, suppresswarnings, util

The ForwardingSortedSet.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 java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.SortedSet;

import javax.annotation.Nullable;

/**
 * A sorted set which forwards all its method calls to another sorted set.
 * Subclasses should override one or more methods to modify the behavior of the
 * backing sorted set as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>Warning: The methods of {@code ForwardingSortedSet} forward
 * <i>indiscriminately to the methods of the delegate. For example,
 * overriding {@link #add} alone <i>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 ForwardingSortedSet}.
 *
 * <p>Each of the {@code standard} methods, where appropriate, uses the set's
 * comparator (or the natural ordering of the elements, if there is no
 * comparator) to test element equality. As a result, if the comparator is not
 * consistent with equals, some of the standard implementations may violate the
 * {@code Set} contract.
 *
 * <p>The {@code standard} methods and the 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 ForwardingSortedSet<E> extends ForwardingSet implements SortedSet {

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

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

  @Override
  public Comparator<? super E> comparator() {
    return delegate().comparator();
  }

  @Override
  public E first() {
    return delegate().first();
  }

  @Override
  public SortedSet<E> headSet(E toElement) {
    return delegate().headSet(toElement);
  }

  @Override
  public E last() {
    return delegate().last();
  }

  @Override
  public SortedSet<E> subSet(E fromElement, E toElement) {
    return delegate().subSet(fromElement, toElement);
  }

  @Override
  public SortedSet<E> tailSet(E fromElement) {
    return delegate().tailSet(fromElement);
  }

  // unsafe, but worst case is a CCE is thrown, which callers will be expecting
  @SuppressWarnings("unchecked")
  private int unsafeCompare(Object o1, Object o2) {
    Comparator<? super E> comparator = comparator();
    return (comparator == null)
        ? ((Comparable<Object>) o1).compareTo(o2)
        : ((Comparator<Object>) comparator).compare(o1, o2);
  }

  /**
   * A sensible definition of {@link #contains} in terms of the {@code first()}
   * method of {@link #tailSet}. If you override {@link #tailSet}, you may wish
   * to override {@link #contains} to forward to this implementation.
   *
   * @since 7.0
   */
  @Override
  @Beta
  protected boolean standardContains(@Nullable Object object) {
    try {
      // any ClassCastExceptions are caught
      @SuppressWarnings("unchecked")
      SortedSet<Object> self = (SortedSet