StringSupport.java

/*
 * Copyright (c) 2015, Nils Braden
 *
 * This file is part of ttrss-reader-fork. This program is free software; you
 * can redistribute it and/or modify it under the terms of the GNU
 * General Public License as published by the Free Software Foundation;
 * either version 3 of the License, or (at your option) any later
 * version.
 *
 * This program 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
 * General Public License for more details. You should have received a
 * copy of the GNU General Public License along with this program; If
 * not, see http://www.gnu.org/licenses/.
 */

package org.ttrssreader.utils;

import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

// contains code from the Apache Software foundation
public class StringSupport {

	/**
	 * Splits the ids into Sets of Strings with maxCount ids each.
	 *
	 * @param values   the set of ids to be split
	 * @param maxCount the maximum length of each list
	 * @return a set of Strings with comma-separated ids
	 */
	public static <T> Set<String> convertListToString(Collection<T> values, int maxCount) {
		Set<String> ret = new HashSet<>();
		if (values == null || values.isEmpty()) return ret;

		StringBuilder sb = new StringBuilder();
		int count = 0;

		for (T t : values) {
			sb.append(t);

			if (count == maxCount) {
				ret.add(sb.substring(0, sb.length() - 1));
				sb = new StringBuilder();
				count = 0;
			} else {
				sb.append(",");
				count++;
			}
		}

		if (sb.length() > 0) ret.add(sb.substring(0, sb.length() - 1));

		return ret;
	}

	public static String[] setToArray(Set<String> set) {
		String[] ret = new String[set.size()];
		int i = 0;
		for (String s : set) {
			ret[i++] = s;
		}
		return ret;
	}

	public static boolean isEmpty(String string) {
		return string == null || string.isEmpty();
	}

}