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/*
* Copyright (C) 2008 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 java.util.Collection;
import javax.annotation.Nullable;
/**
* An empty immutable multiset.
*
* @author Jared Levy
* @author Louis Wasserman
*/
@GwtCompatible(serializable = true)
final class EmptyImmutableMultiset extends ImmutableMultiset<Object> {
static final EmptyImmutableMultiset INSTANCE = new EmptyImmutableMultiset();
@Override
public int count(@Nullable Object element) {
return 0;
}
@Override
public boolean contains(@Nullable Object object) {
return false;
}
@Override
public boolean containsAll(Collection<?> targets) {
return targets.isEmpty();
}
@Override
public UnmodifiableIterator<Object> iterator() {
return Iterators.emptyIterator();
}
@Override
public boolean equals(@Nullable Object object) {
if (object instanceof Multiset) {
Multiset<?> other = (Multiset<?>) object;
return other.isEmpty();
}
return false;
}
@Override
public int hashCode() {
return 0;
}
@Override
public ImmutableSet<Object> elementSet() {
return ImmutableSet.of();
}
@Override
public ImmutableSet<Entry<Object>> entrySet() {
return ImmutableSet.of();
}
@Override
ImmutableSet<Entry<Object>> createEntrySet() {
throw new AssertionError("should never be called");
}
@Override
public int size() {
return 0;
}
@Override
boolean isPartialView() {
return false;
}
@Override
public Object[] toArray() {
return ObjectArrays.EMPTY_ARRAY;
}
@Override
public <T> T[] toArray(T[] other) {
return asList().toArray(other);
}
@Override
public ImmutableList<Object> asList() {
return ImmutableList.of();
}
Object readResolve() {
return INSTANCE; // preserve singleton property
}
private static final long serialVersionUID = 0;
}
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