com.google.common.collect.EnumHashBiMap Maven / Gradle / Ivy
/*
* 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 static com.google.common.base.Preconditions.checkNotNull;
import static java.util.Objects.requireNonNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A {@code BiMap} backed by an {@code EnumMap} instance for keys-to-values, and a {@code HashMap}
* instance for values-to-keys. Null keys are not permitted, but null values are. An {@code
* EnumHashBiMap} and its inverse are both serializable.
*
* See the Guava User Guide article on {@code BiMap}.
*
* @author Mike Bostock
* @since 2.0
*/
@GwtCompatible(emulated = true)
@J2ktIncompatible
@ElementTypesAreNonnullByDefault
public final class EnumHashBiMap, V extends @Nullable Object>
extends AbstractBiMap {
transient Class keyTypeOrObjectUnderJ2cl;
/**
* Returns a new, empty {@code EnumHashBiMap} using the specified key type.
*
* @param keyType the key type
*/
public static , V extends @Nullable Object> EnumHashBiMap create(
Class keyType) {
return new EnumHashBiMap<>(keyType);
}
/**
* Constructs a new bimap with the same mappings as the specified map. If the specified map is an
* {@code EnumHashBiMap} or an {@link EnumBiMap}, the new bimap has the same key type as the input
* bimap. Otherwise, the specified map must contain at least one mapping, in order to determine
* the key type.
*
* @param map the map whose mappings are to be placed in this map
* @throws IllegalArgumentException if map is not an {@code EnumBiMap} or an {@code EnumHashBiMap}
* instance and contains no mappings
*/
public static , V extends @Nullable Object> EnumHashBiMap create(
Map map) {
EnumHashBiMap bimap = create(EnumBiMap.inferKeyTypeOrObjectUnderJ2cl(map));
bimap.putAll(map);
return bimap;
}
private EnumHashBiMap(Class keyType) {
super(new EnumMap(keyType), new HashMap());
// TODO: cpovirk - Pre-size the HashMap based on the number of enum values?
this.keyTypeOrObjectUnderJ2cl = keyType;
}
// Overriding these 3 methods to show that values may be null (but not keys)
@Override
K checkKey(K key) {
return checkNotNull(key);
}
@CanIgnoreReturnValue
@Override
@SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
// TODO(b/192446998): Remove this override after tools understand nullness better.
@CheckForNull
public V put(K key, @ParametricNullness V value) {
return super.put(key, value);
}
@CanIgnoreReturnValue
@Override
@SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
// TODO(b/192446998): Remove this override after tools understand nullness better.
@CheckForNull
public V forcePut(K key, @ParametricNullness V value) {
return super.forcePut(key, value);
}
/** Returns the associated key type. */
@GwtIncompatible
public Class keyType() {
return keyTypeOrObjectUnderJ2cl;
}
/**
* @serialData the key class, number of entries, first key, first value, second key, second value,
* and so on.
*/
@GwtIncompatible // java.io.ObjectOutputStream
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(keyTypeOrObjectUnderJ2cl);
Serialization.writeMap(this, stream);
}
@SuppressWarnings("unchecked") // reading field populated by writeObject
@GwtIncompatible // java.io.ObjectInputStream
private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyTypeOrObjectUnderJ2cl = (Class) requireNonNull(stream.readObject());
/*
* TODO: cpovirk - Pre-size the HashMap based on the number of enum values? (But *not* based on
* the number of entries in the map, as that makes it easy for hostile inputs to trigger lots of
* allocation—not that any program should be deserializing hostile inputs to begin with!)
*/
setDelegates(new EnumMap(keyTypeOrObjectUnderJ2cl), new HashMap());
Serialization.populateMap(this, stream);
}
@GwtIncompatible // only needed in emulated source.
private static final long serialVersionUID = 0;
}