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fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists, and queues with a small memory footprint and fast operations; it provides also big (64-bit) arrays, sets, and lists, sorting algorithms, fast, practical I/O classes for binary and text files, and facilities for memory mapping large files. This jar (fastutil-core.jar) contains data structures based on integers, longs, doubles, and objects, only; fastutil.jar contains all classes. If you have both jars in your dependencies, this jar should be excluded.

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/*
	* Copyright (C) 2002-2021 Sebastiano Vigna
	*
	* 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 it.unimi.dsi.fastutil.objects;
import java.util.Set;
/**
 * An abstract class providing basic methods for sets implementing a
 * type-specific interface.
 *
 * 
 * Note that the type-specific {@link Set} interface adds a type-specific
 * {@code remove()} method, as it is no longer harmful for subclasses. Thus,
 * concrete subclasses of this class must implement {@code remove()} (the
 * {@code rem()} implementation of this class just delegates to
 * {@code remove()}).
 */
public abstract class AbstractObjectSet extends AbstractObjectCollection implements Cloneable, ObjectSet {
	protected AbstractObjectSet() {
	}
	@Override
	public abstract ObjectIterator iterator();
	@Override
	public boolean equals(final Object o) {
		if (o == this)
			return true;
		if (!(o instanceof Set))
			return false;
		Set s = (Set) o;
		if (s.size() != size())
			return false;
		return containsAll(s);
	}
	/**
	 * Returns a hash code for this set.
	 *
	 * The hash code of a set is computed by summing the hash codes of its elements.
	 *
	 * @return a hash code for this set.
	 */
	@Override
	public int hashCode() {
		int h = 0, n = size();
		ObjectIterator i = iterator();
		K k;
		while (n-- != 0) {
			k = i.next(); // We need k because KEY2JAVAHASH() is a macro with repeated evaluation.
			h += ((k) == null ? 0 : (k).hashCode());
		}
		return h;
	}
}