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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) 2002-2022 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.AbstractCollection;

/**
 * An abstract class providing basic methods for collections implementing a type-specific interface.
 *
 * 
 * In particular, this class provide {@link #iterator()}, {@code add()}, {@link #remove(Object)} and
 * {@link #contains(Object)} methods that just call the type-specific counterpart.
 *
 * 
 * Warning: Because of a name clash between the list and collection interfaces the
 * type-specific deletion method of a type-specific abstract collection is {@code rem()}, rather
 * then {@code remove()}. A subclass must thus override {@code rem()}, rather than {@code remove()},
 * to make all inherited methods work properly.
 */
public abstract class AbstractObjectCollection extends AbstractCollection implements ObjectCollection {
	protected AbstractObjectCollection() {
	}

	@Override
	public abstract ObjectIterator iterator();

	@Override
	public String toString() {
		final StringBuilder s = new StringBuilder();
		final ObjectIterator i = iterator();
		int n = size();
		Object k;
		boolean first = true;
		s.append("{");
		while (n-- != 0) {
			if (first) first = false;
			else s.append(", ");
			k = i.next();
			if (this == k) s.append("(this collection)");
			else s.append(String.valueOf(k));
		}
		s.append("}");
		return s.toString();
	}
}