/
MinimalSet.java
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/
MinimalSet.java
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/*
* 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.testing;
import com.google.common.annotations.GwtCompatible;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A simplistic set which implements the bare minimum so that it can be used in tests without
* relying on any specific Set implementations. Slow. Explicitly allows null elements so that they
* can be used in the testers.
*
* @author Regina O'Dell
*/
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class MinimalSet<E extends @Nullable Object> extends MinimalCollection<E> implements Set<E> {
@SuppressWarnings("unchecked") // empty Object[] as E[]
public static <E extends @Nullable Object> MinimalSet<E> of(E... contents) {
return ofClassAndContents(Object.class, (E[]) new Object[0], Arrays.asList(contents));
}
@SuppressWarnings("unchecked") // empty Object[] as E[]
public static <E extends @Nullable Object> MinimalSet<E> from(Collection<? extends E> contents) {
return ofClassAndContents(Object.class, (E[]) new Object[0], contents);
}
public static <E extends @Nullable Object> MinimalSet<E> ofClassAndContents(
Class<? super @NonNull E> type, E[] emptyArrayForContents, Iterable<? extends E> contents) {
List<E> setContents = new ArrayList<>();
for (E e : contents) {
if (!setContents.contains(e)) {
setContents.add(e);
}
}
return new MinimalSet<>(type, setContents.toArray(emptyArrayForContents));
}
private MinimalSet(Class<? super @NonNull E> type, E... contents) {
super(type, true, contents);
}
/*
* equals() and hashCode() are more specific in the Set contract.
*/
@Override
public boolean equals(@Nullable Object object) {
if (object instanceof Set) {
Set<?> that = (Set<?>) object;
return (this.size() == that.size()) && this.containsAll(that);
}
return false;
}
@Override
public int hashCode() {
int hashCodeSum = 0;
for (Object o : this) {
hashCodeSum += (o == null) ? 0 : o.hashCode();
}
return hashCodeSum;
}
}