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This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * 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.GwtCompatible;
import com.google.common.base.Preconditions;
import com.google.errorprone.annotations.concurrent.LazyInit;

/**
 * Implementation of {@link ImmutableSet} with exactly one element.
 *
 * @author Kevin Bourrillion
 * @author Nick Kralevich
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
final class SingletonImmutableSet extends ImmutableSet {

  final transient E element;
  // This is transient because it will be recalculated on the first
  // call to hashCode().
  //
  // A race condition is avoided since threads will either see that the value
  // is zero and recalculate it themselves, or two threads will see it at
  // the same time, and both recalculate it.  If the cachedHashCode is 0,
  // it will always be recalculated, unfortunately.
  @LazyInit private transient int cachedHashCode;

  SingletonImmutableSet(E element) {
    this.element = Preconditions.checkNotNull(element);
  }

  SingletonImmutableSet(E element, int hashCode) {
    // Guaranteed to be non-null by the presence of the pre-computed hash code.
    this.element = element;
    cachedHashCode = hashCode;
  }

  @Override
  public int size() {
    return 1;
  }

  @Override
  public boolean contains(Object target) {
    return element.equals(target);
  }

  @Override
  public UnmodifiableIterator iterator() {
    return Iterators.singletonIterator(element);
  }

  @Override
  ImmutableList createAsList() {
    return ImmutableList.of(element);
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  int copyIntoArray(Object[] dst, int offset) {
    dst[offset] = element;
    return offset + 1;
  }

  @Override
  public final int hashCode() {
    // Racy single-check.
    int code = cachedHashCode;
    if (code == 0) {
      cachedHashCode = code = element.hashCode();
    }
    return code;
  }

  @Override
  boolean isHashCodeFast() {
    return cachedHashCode != 0;
  }

  @Override
  public String toString() {
    return '[' + element.toString() + ']';
  }
}