ru.yandex.clickhouse.util.apache.StringUtils Maven / Gradle / Ivy

/*
 * Copyright 2016 YANDEX LLC
 *
 * 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.
 */

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 ru.yandex.clickhouse.util.apache;

import java.util.Iterator;


public class StringUtils {
    public static boolean isBlank(final CharSequence cs) {
        int strLen;
        if (cs == null || (strLen = cs.length()) == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(cs.charAt(i))) {
                return false;
            }
        }
        return true;
    }

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

    public static String join(final Iterable iterable, final char separator) {

        Iterator iterator = iterable.iterator();

        // handle null, zero and one elements before building a buffer
        if (iterator == null) {
            return null;
        }
        if (!iterator.hasNext()) {
            return "";
        }
        final Object first = iterator.next();
        if (!iterator.hasNext()) {
            return first == null ? "" : first.toString();
        }

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

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

        return buf.toString();
    }
}