com.google.common.collect.LinkedHashMultiset Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of google-collect Show documentation
Google Collections Library is a suite of new collections and collection-related goodness for Java 5.0
The newest version!
/*
 * Copyright (C) 2007 Google Inc.
 *
 * 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 java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.util.LinkedHashMap;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * A {@code Multiset} implementation with predictable iteration order. Its
 * iterator orders elements according to when the first occurrence of the
 * element was added. When the multiset contains multiple instances of an
 * element, those instances are consecutive in the iteration order. If all
 * occurrences of an element are removed, after which that element is added to
 * the multiset, the element will appear at the end of the iteration.
 * 
 * @author Kevin Bourrillion
 * @author Jared Levy
 */
@SuppressWarnings("serial") // we're overriding default serialization
public final class LinkedHashMultiset extends AbstractMapBasedMultiset {
  /**
   * Constructs a new empty {@code LinkedHashMultiset} using the default initial
   * capacity (16 distinct elements) and load factor (0.75).
   */
  public LinkedHashMultiset() {
    super(new LinkedHashMap());
  }

  /**
   * Constructs a new empty {@code LinkedHashMultiset} with the specified
   * expected number of distinct elements and the default load factor (0.75).
   *
   * @param distinctElements the expected number of distinct elements
   * @throws IllegalArgumentException if {@code distinctElements} is negative
   */
  public LinkedHashMultiset(int distinctElements) {
    // Could use newLinkedHashMapWithExpectedSize() if it existed
    super(new LinkedHashMap(Maps.capacity(distinctElements)));
  }

  /**
   * Constructs a new {@code LinkedHashMultiset} containing the specified
   * elements.
   * 
   * @param elements the elements that the multiset should contain
   */
  public LinkedHashMultiset(Iterable elements) {
    this(Multisets.inferDistinctElements(elements));
    Iterables.addAll(this, elements); // careful if we make this class non-final
  }

  private static class SerializedForm extends MultisetSerializedForm {
    SerializedForm(Multiset multiset) {
      super(multiset);
    }
    @Override protected Multiset createEmpty() {
      return new LinkedHashMultiset(elementCount());
    }
    private static final long serialVersionUID = 0;
  }

  private void readObject(ObjectInputStream stream)
      throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  private Object writeReplace() {
    return new SerializedForm(this);
  }
}