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/**
* 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.
*/
/**
* Operations on {@link java.lang.String} that are
* <code>null</code> safe.
*
* @see java.lang.String
* @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a>
* @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
* @author Daniel L. Rall
* @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a>
* @author <a href="mailto:ed@apache.org">Ed Korthof</a>
* @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a>
* @author Stephen Colebourne
* @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
* @author Holger Krauth
* @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>
* @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
* @author Arun Mammen Thomas
* @author Gary Gregory
* @author Phil Steitz
* @author Al Chou
* @author Michael Davey
* @author Reuben Sivan
* @author Chris Hyzer
* @author Scott Johnson
* @since 1.0
* @version $Id: StringUtils.java 635447 2008-03-10 06:27:09Z bayard $
*/
public class Main {
/**
* Gets a substring from the specified String avoiding exceptions.
*
* A negative start position can be used to start/end <code>n</code>
* characters from the end of the String.
*
* The returned substring starts with the character in the <code>start</code>
* position and ends before the <code>end</code> position. All position counting is
* zero-based -- i.e., to start at the beginning of the string use
* <code>start = 0</code>. Negative start and end positions can be used to
* specify offsets relative to the end of the String.
*
* If <code>start</code> is not strictly to the left of <code>end</code>, ""
* is returned.
*
* <pre>
* StringUtils.substring(null, *, *) = null
* StringUtils.substring("", * , *) = "";
* StringUtils.substring("abc", 0, 2) = "ab"
* StringUtils.substring("abc", 2, 0) = ""
* StringUtils.substring("abc", 2, 4) = "c"
* StringUtils.substring("abc", 4, 6) = ""
* StringUtils.substring("abc", 2, 2) = ""
* StringUtils.substring("abc", -2, -1) = "b"
* StringUtils.substring("abc", -4, 2) = "ab"
* </pre>
*
* @param str the String to get the substring from, may be null
* @param start the position to start from, negative means
* count back from the end of the String by this many characters
* @param end the position to end at (exclusive), negative means
* count back from the end of the String by this many characters
* @return substring from start position to end positon,
* <code>null</code> if null String input
*/
public static String substring(String str, int start, int end) {
if (str == null) {
return null;
}
// handle negatives
if (end < 0) {
end = str.length() + end; // remember end is negative
}
if (start < 0) {
start = str.length() + start; // remember start is negative
}
// check length next
if (end > str.length()) {
end = str.length();
}
// if start is greater than end, return ""
if (start > end) {
return "";
}
if (start < 0) {
start = 0;
}
if (end < 0) {
end = 0;
}
return str.substring(start, end);
}
}
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