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1000kit mvc library for the Quarkus framework
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/*
 * Copyright (c) 2011, 1000kit.org, and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This 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 software 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.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.tkit.jee.base.util;

import java.util.Collection;
import java.util.Iterator;

/**
 * Common string operations in one spot.
 *
 *
 * @author Matus_Majchrak
 */
public class StringUtils {

    private static final String EMPTY = "";

    /**
     * Check is a String is empty.
     *
     * @param str the String to check, may be null.
     * @return true if the String is null or empty.
     */
    public static boolean isEmpty(String str) {
        return str == null || str.isEmpty();
    }

    /**
     * 
     * Checks if a String is whitespace, empty ("") or null.
     * 
     *
     *      * StringUtils.isBlank(null)      = true
     * StringUtils.isBlank("")        = true
     * StringUtils.isBlank(" ")       = true
     * StringUtils.isBlank("bob")     = false
     * StringUtils.isBlank("  bob  ") = false
     * 
     *
     * @param str the String to check, may be null
     * @return true if the String is null, empty or whitespace
     */
    public static boolean isBlank(String str) {
        int strLen;
        if (str == null || (strLen = str.length()) == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if ((Character.isWhitespace(str.charAt(i)) == false)) {
                return false;
            }
        }
        return true;
    }

    /**
     * 
     * Checks if a String is not empty (""), not null and not whitespace only.
     * 
     *
     *      * StringUtils.isNotBlank(null)      = false
     * StringUtils.isNotBlank("")        = false
     * StringUtils.isNotBlank(" ")       = false
     * StringUtils.isNotBlank("bob")     = true
     * StringUtils.isNotBlank("  bob  ") = true
     * 
     *
     * @param str the String to check, may be null
     * @return true if the String is not empty and not null and not whitespace
     */
    public static boolean isNotBlank(String str) {
        return !StringUtils.isBlank(str);
    }

    public static String join(Collection items) {
        return join(items, ", ");
    }

    public static String join(Collection items, String separator) {
        if (items == null) {
            return null;
        }
        Iterator iterator = items.iterator();
        // handle null, zero and one elements before building a buffer
        if (iterator == null) {
            return null;
        }
        if (!iterator.hasNext()) {
            return EMPTY;
        }
        Object first = iterator.next();
        if (!iterator.hasNext()) {
            return ""+first;
        }

        // two or more elements
        StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small
        if (first != null) {
            buf.append(first);
        }

        while (iterator.hasNext()) {
            if (separator != null) {
                buf.append(separator);
            }
            Object obj = iterator.next();
            if (obj != null) {
                buf.append(obj);
            }
        }
        return buf.toString();
    }
}