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/*
* 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 com.google.common.annotations.GwtCompatible;
import static com.google.common.base.Preconditions.checkNotNull;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import javax.annotation.Nullable;
/**
* Implementation of {@code Multimap} whose keys and values are ordered by
* their natural ordering or by supplied comparators. In all cases, this
* implementation uses {@link Comparable#compareTo} or {@link
* Comparator#compare} instead of {@link Object#equals} to determine
* equivalence of instances.
*
* Warning: The comparators or comparables used must be consistent
* with equals as explained by the {@link Comparable} class specification.
* Otherwise, the resulting multiset will violate the general contract of {@link
* SetMultimap}, which it is specified in terms of {@link Object#equals}.
*
*
The collections returned by {@code keySet} and {@code asMap} iterate
* through the keys according to the key comparator ordering or the natural
* ordering of the keys. Similarly, {@code get}, {@code removeAll}, and {@code
* replaceValues} return collections that iterate through the values according
* to the value comparator ordering or the natural ordering of the values. The
* collections generated by {@code entries}, {@code keys}, and {@code values}
* iterate across the keys according to the above key ordering, and for each
* key they iterate across the values according to the value ordering.
*
*
The multimap does not store duplicate key-value pairs. Adding a new
* key-value pair equal to an existing key-value pair has no effect.
*
*
Depending on the comparators, null keys and values may or may not be
* supported. The natural ordering does not support nulls. All optional multimap
* methods are supported, and all returned views are modifiable.
*
*
This class is not threadsafe when any concurrent operations update the
* multimap. Concurrent read operations will work correctly. To allow concurrent
* update operations, wrap your multimap with a call to {@link
* Multimaps#synchronizedSortedSetMultimap}.
*
* @author Jared Levy
*/
@GwtCompatible(serializable = true)
public class TreeMultimap extends AbstractSortedSetMultimap {
private transient Comparator keyComparator;
private transient Comparator valueComparator;
/**
* Creates an empty {@code TreeMultimap} ordered by the natural ordering of
* its keys and values.
*/
@SuppressWarnings("unchecked") // eclipse doesn't like the raw Comparable
public static
TreeMultimap create() {
return new TreeMultimap(Ordering.natural(), Ordering.natural());
}
/**
* Creates an empty {@code TreeMultimap} instance using explicit comparators.
* Neither comparator may be null; use {@link Ordering#natural()} to specify
* natural order.
*
* @param keyComparator the comparator that determines the key ordering
* @param valueComparator the comparator that determines the value ordering
*/
public static TreeMultimap create(
Comparator keyComparator,
Comparator valueComparator) {
return new TreeMultimap(checkNotNull(keyComparator),
checkNotNull(valueComparator));
}
/**
* Constructs a {@code TreeMultimap}, ordered by the natural ordering of its
* keys and values, with the same mappings as the specified multimap.
*
* @param multimap the multimap whose contents are copied to this multimap
*/
@SuppressWarnings("unchecked") // eclipse doesn't like the raw Comparable
public static
TreeMultimap create(Multimap multimap) {
return new TreeMultimap(Ordering.natural(), Ordering.natural(),
multimap);
}
// Used by the TreeMultimap serialization test.
TreeMultimap() {
this(null, null);
}
// Must be package-private so multimaps with null comparators can be
// serialized (which can be created with Multimaps.newTreeMultimap()). Once
// that method is removed, this constructor can be made private.
TreeMultimap(@Nullable Comparator keyComparator,
@Nullable Comparator valueComparator) {
super((keyComparator == null)
? new TreeMap>()
: new TreeMap>(keyComparator));
this.keyComparator = keyComparator;
this.valueComparator = valueComparator;
}
private TreeMultimap(Comparator keyComparator,
Comparator valueComparator,
Multimap multimap) {
this(keyComparator, valueComparator);
putAll(multimap);
}
/**
* {@inheritDoc}
*
* Creates an empty {@code TreeSet} for a collection of values for one key.
*
* @return a new {@code TreeSet} containing a collection of values for one
* key
*/
@Override SortedSet createCollection() {
return (valueComparator == null)
? new TreeSet() : new TreeSet(valueComparator);
}
/**
* Returns the comparator that orders the multimap keys.
*/
public Comparator keyComparator() {
return keyComparator;
}
public Comparator valueComparator() {
return valueComparator;
}
/**
* {@inheritDoc}
*
* Because a {@code TreeMultimap} has unique sorted keys, this method
* returns a {@link SortedSet}, instead of the {@link Set} specified in the
* {@link Multimap} interface.
*/
@Override public SortedSet keySet() {
return (SortedSet) super.keySet();
}
/**
* {@inheritDoc}
*
* Because a {@code TreeMultimap} has unique sorted keys, this method
* returns a {@link SortedMap}, instead of the {@link java.util.Map} specified
* in the {@link Multimap} interface.
*/
@Override public SortedMap> asMap() {
return (SortedMap>) super.asMap();
}
/**
* @serialData key comparator, value comparator, number of distinct keys, and
* then for each distinct key: the key, number of values for that key, and
* key values
*/
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(keyComparator());
stream.writeObject(valueComparator());
Serialization.writeMultimap(this, stream);
}
@SuppressWarnings("unchecked") // reading data stored by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyComparator = (Comparator) stream.readObject();
valueComparator = (Comparator) stream.readObject();
setMap(new TreeMap>(keyComparator));
Serialization.populateMultimap(this, stream);
}
private static final long serialVersionUID = 0;
}