SetUtil.java

/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 */

package com.liferay.portal.kernel.util;

import com.liferay.portal.kernel.io.unsync.UnsyncBufferedReader;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

/**
 * @author Brian Wing Shun Chan
 */
public class SetUtil {

	public static Set<Boolean> fromArray(boolean[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Boolean> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Byte> fromArray(byte[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Byte> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Character> fromArray(char[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Character> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Double> fromArray(double[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Double> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static <E> Set<E> fromArray(E[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<E> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Float> fromArray(float[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Float> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Integer> fromArray(int[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Integer> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Long> fromArray(long[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Long> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static Set<Short> fromArray(short[] array) {
		if (ArrayUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		Set<Short> set = new HashSet<>(array.length);

		for (int i = 0; i < array.length; i++) {
			set.add(array[i]);
		}

		return set;
	}

	public static <E> Set<E> fromCollection(Collection<? extends E> c) {
		if ((c != null) && (c instanceof Set)) {
			return (Set<E>)c;
		}

		if ((c == null) || c.isEmpty()) {
			return new HashSet<>();
		}

		return new HashSet<>(c);
	}

	public static <E> Set<E> fromEnumeration(Enumeration<? extends E> enu) {
		Set<E> set = new HashSet<>();

		while (enu.hasMoreElements()) {
			set.add(enu.nextElement());
		}

		return set;
	}

	public static Set<String> fromFile(File file) throws IOException {
		Set<String> set = new HashSet<>();

		try (UnsyncBufferedReader unsyncBufferedReader =
				new UnsyncBufferedReader(new FileReader(file))) {

			String s = StringPool.BLANK;

			while ((s = unsyncBufferedReader.readLine()) != null) {
				set.add(s);
			}
		}

		return set;
	}

	public static Set<String> fromFile(String fileName) throws IOException {
		return fromFile(new File(fileName));
	}

	public static <E> Set<E> fromIterator(Iterator<E> itr) {
		Set<E> set = new HashSet<>();

		while (itr.hasNext()) {
			set.add(itr.next());
		}

		return set;
	}

	public static <E> Set<E> fromList(List<? extends E> array) {
		if (ListUtil.isEmpty(array)) {
			return new HashSet<>();
		}

		return new HashSet<>(array);
	}

	public static Set<String> fromString(String s) {
		return fromArray(StringUtil.splitLines(s));
	}

	public static <T> Set<T> intersect(
		Collection<T> collection1, Collection<T> collection2) {

		if (collection1.isEmpty() || collection2.isEmpty()) {
			return Collections.emptySet();
		}

		Set<T> set1 = _toSet(collection1);
		Set<T> set2 = _toSet(collection2);

		if (set1.size() > set2.size()) {
			set2.retainAll(set1);

			return set2;
		}

		set1.retainAll(set2);

		return set1;
	}

	public static Set<Long> intersect(long[] array1, long[] array2) {
		return intersect(fromArray(array1), fromArray(array2));
	}

	public static boolean isEmpty(Set<?> set) {
		if ((set == null) || set.isEmpty()) {
			return true;
		}

		return false;
	}

	public static boolean isNotEmpty(Set<?> set) {
		return !isEmpty(set);
	}

	public static <T> Set<T> symmetricDifference(
		Collection<T> collection1, Collection<T> collection2) {

		if (collection1.isEmpty()) {
			return _toSet(collection2);
		}

		if (collection2.isEmpty()) {
			return _toSet(collection1);
		}

		Set<T> set1 = _toSet(collection1);
		Set<T> set2 = _toSet(collection2);

		Set<T> intersection = intersect(set1, set2);

		if (set1.size() > set2.size()) {
			set1.addAll(set2);
		}
		else {
			set2.addAll(set1);

			set1 = set2;
		}

		set1.removeAll(intersection);

		return set1;
	}

	public static Set<Long> symmetricDifference(long[] array1, long[] array2) {
		return symmetricDifference(fromArray(array1), fromArray(array2));
	}

	private static <T> Set<T> _toSet(Collection<T> collection) {
		if (collection instanceof Set) {
			return (Set<T>)collection;
		}

		return new HashSet<>(collection);
	}

}