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Java example source code file (ImmutableEnumSet.java)
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The ImmutableEnumSet.java Java example source code
/*
* Copyright (C) 2009 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.io.Serializable;
import java.util.Collection;
import java.util.EnumSet;
/**
* Implementation of {@link ImmutableSet} backed by a non-empty {@link
* java.util.EnumSet}.
*
* @author Jared Levy
*/
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
final class ImmutableEnumSet<E extends Enum extends ImmutableSet {
@SuppressWarnings("rawtypes") // necessary to compile against Java 8
static ImmutableSet asImmutable(EnumSet set) {
switch (set.size()) {
case 0:
return ImmutableSet.of();
case 1:
return ImmutableSet.of(Iterables.getOnlyElement(set));
default:
return new ImmutableEnumSet(set);
}
}
/*
* Notes on EnumSet and <E extends Enum:
*
* This class isn't an arbitrary ForwardingImmutableSet because we need to
* know that calling {@code clone()} during deserialization will return an
* object that no one else has a reference to, allowing us to guarantee
* immutability. Hence, we support only {@link EnumSet}.
*/
private final transient EnumSet<E> delegate;
private ImmutableEnumSet(EnumSet<E> delegate) {
this.delegate = delegate;
}
@Override
boolean isPartialView() {
return false;
}
@Override
public UnmodifiableIterator<E> iterator() {
return Iterators.unmodifiableIterator(delegate.iterator());
}
@Override
public int size() {
return delegate.size();
}
@Override
public boolean contains(Object object) {
return delegate.contains(object);
}
@Override
public boolean containsAll(Collection<?> collection) {
if (collection instanceof ImmutableEnumSet<?>) {
collection = ((ImmutableEnumSet<?>) collection).delegate;
}
return delegate.containsAll(collection);
}
@Override
public boolean isEmpty() {
return delegate.isEmpty();
}
@Override
public boolean equals(Object object) {
if (object == this) {
return true;
}
if (object instanceof ImmutableEnumSet) {
object = ((ImmutableEnumSet<?>) object).delegate;
}
return delegate.equals(object);
}
@Override
boolean isHashCodeFast() {
return true;
}
private transient int hashCode;
@Override
public int hashCode() {
int result = hashCode;
return (result == 0) ? hashCode = delegate.hashCode() : result;
}
@Override
public String toString() {
return delegate.toString();
}
// All callers of the constructor are restricted to <E extends Enum.
@Override
Object writeReplace() {
return new EnumSerializedForm<E>(delegate);
}
/*
* This class is used to serialize ImmutableEnumSet instances.
*/
private static class EnumSerializedForm<E extends Enum implements Serializable {
final EnumSet<E> delegate;
EnumSerializedForm(EnumSet<E> delegate) {
this.delegate = delegate;
}
Object readResolve() {
// EJ2 #76: Write readObject() methods defensively.
return new ImmutableEnumSet<E>(delegate.clone());
}
private static final long serialVersionUID = 0;
}
}
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