001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.lang3;
018
019 /**
020 * Null-safe CharSequence utility methods.
021 *
022 * @author Gary Gregory
023 * @version $Id: CharSequenceUtils.java 967237 2010-07-23 20:08:57Z mbenson $
024 */
025 public class CharSequenceUtils {
026
027 /**
028 * Gets a CharSequence length or <code>0</code> if the CharSequence is
029 * <code>null</code>.
030 *
031 * @param cs
032 * a CharSequence or <code>null</code>
033 * @return CharSequence length or <code>0</code> if the CharSequence is
034 * <code>null</code>.
035 * @since 3.0
036 */
037 public static int length(CharSequence cs) {
038 return cs == null ? 0 : cs.length();
039 }
040
041 /**
042 * Returns a new <code>CharSequence</code> that is a subsequence of this
043 * sequence starting with the <code>char</code> value at the specified
044 * index. The length (in <code>char</code>s) of the returned sequence is
045 * <code>length() - start</code>, so if <code>start == end</code> then an
046 * empty sequence is returned. </p>
047 *
048 * @param cs
049 * the specified subsequence, may be null
050 * @param start
051 * the start index, inclusive
052 * @return a new subsequence or null
053 *
054 * @throws IndexOutOfBoundsException
055 * if <code>start</code> is negative or if <code>start</code> is
056 * greater than <code>length()</code>
057 * @since 3.0
058 */
059 public static CharSequence subSequence(CharSequence cs, int start) {
060 return cs == null ? null : cs.subSequence(start, cs.length());
061 }
062 }