StringUtils

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
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 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.codehaus.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
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package org.codehaus.plexus.util;

import java.util.Arrays;
import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.StringTokenizer;

/**
 * <p>
 * Common <code>String</code> manipulation routines.
 * </p>
 * <p>
 * Originally from <a href="http://jakarta.apache.org/turbine/">Turbine</a> and the GenerationJavaCore library.
 * </p>
 *
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
 * @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a>
 * @author <a href="mailto:bayard@generationjava.com">Henri Yandell</a>
 * @author <a href="mailto:ed@codehaus.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:vincent.siveton@gmail.com">Vincent Siveton</a>
 * @since 1.0
 *
 */
public class StringUtils {
    /**
     * <p>
     * <code>StringUtils</code> instances should NOT be constructed in standard programming. Instead, the class should
     * be used as <code>StringUtils.trim(" foo ");</code>.
     * </p>
     * <p>
     * This constructor is public to permit tools that require a JavaBean manager to operate.
     * </p>
     */
    public StringUtils() {}

    // Empty
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Removes control characters, including whitespace, from both ends of this String, handling <code>null</code> by
     * returning an empty String.
     * </p>
     *
     * @see java.lang.String#trim()
     * @param str the String to check
     * @return the trimmed text (never <code>null</code>)
     */
    public static String clean(String str) {
        return (str == null ? "" : str.trim());
    }

    /**
     * <p>
     * Removes control characters, including whitespace, from both ends of this String, handling <code>null</code> by
     * returning <code>null</code>.
     * </p>
     *
     * @see java.lang.String#trim()
     * @param str the String to check
     * @return the trimmed text (or <code>null</code>)
     */
    public static String trim(String str) {
        return (str == null ? null : str.trim());
    }

    /**
     * <p>
     * Deletes all whitespaces from a String.
     * </p>
     * <p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}.
     * </p>
     *
     * @param str String target to delete whitespace from
     * @return the String without whitespaces
     */
    public static String deleteWhitespace(String str) {
        StringBuilder buffer = new StringBuilder();
        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                buffer.append(str.charAt(i));
            }
        }
        return buffer.toString();
    }

    /**
     * Checks if a String is non <code>null</code> and is not empty (<code>length &gt; 0</code>).
     *
     * @param str the String to check
     * @return true if the String is non-null, and not length zero
     */
    public static boolean isNotEmpty(String str) {
        return ((str != null) && (!str.isEmpty()));
    }

    /**
     * Checks if a String is <code>null</code> or empty.
     * <p>
     * <strong>Note:</strong> In releases prior 3.5.0, this method trimmed the input string such that it worked
     * the same as {@link #isBlank(String)}. Since release 3.5.0 it no longer returns {@code true} for strings
     * containing only whitespace characters.
     *
     * @param str the String to check
     * @return <code>true</code> if the String is <code>null</code>, or length zero
     */
    public static boolean isEmpty(String str) {
        return ((str == null) || (str.isEmpty()));
    }

    /**
     * <p>
     * Checks if a String is whitespace, empty ("") or null.
     * </p>
     *
     * <pre>
     * StringUtils.isBlank(null)      = true
     * StringUtils.isBlank("")        = true
     * StringUtils.isBlank(" ")       = true
     * StringUtils.isBlank("bob")     = false
     * StringUtils.isBlank("  bob  ") = false
     * </pre>
     *
     * @param str the String to check, may be null
     * @return <code>true</code> if the String is null, empty or whitespace
     * @since 1.5.2
     */
    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))) {
                return false;
            }
        }
        return true;
    }

    /**
     * <p>
     * Checks if a String is not empty (""), not null and not whitespace only.
     * </p>
     *
     * <pre>
     * StringUtils.isNotBlank(null)      = false
     * StringUtils.isNotBlank("")        = false
     * StringUtils.isNotBlank(" ")       = false
     * StringUtils.isNotBlank("bob")     = true
     * StringUtils.isNotBlank("  bob  ") = true
     * </pre>
     *
     * @param str the String to check, may be null
     * @return <code>true</code> if the String is not empty and not null and not whitespace
     * @since 1.5.2
     */
    public static boolean isNotBlank(String str) {
        return !StringUtils.isBlank(str);
    }

    // Equals and IndexOf
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Compares two Strings, returning <code>true</code> if they are equal.
     * </p>
     * <p>
     * <code>null</code>s are handled without exceptions. Two <code>null</code> references are considered to be equal.
     * The comparison is case sensitive.
     * </p>
     *
     * @see java.lang.String#equals(Object)
     * @param str1 the first string
     * @param str2 the second string
     * @return <code>true</code> if the Strings are equal, case sensitive, or both <code>null</code>
     * @see Objects#equals(Object, Object)
     */
    @Deprecated
    public static boolean equals(String str1, String str2) {
        return Objects.equals(str1, str2);
    }

    /**
     * <p>
     * Compares two Strings, returning <code>true</code> if they are equal ignoring the case.
     * </p>
     * <p>
     * <code>Nulls</code> are handled without exceptions. Two <code>null</code> references are considered equal.
     * Comparison is case insensitive.
     * </p>
     *
     * @see java.lang.String#equalsIgnoreCase(String)
     * @param str1 the first string
     * @param str2 the second string
     * @return <code>true</code> if the Strings are equal, case insensitive, or both <code>null</code>
     */
    public static boolean equalsIgnoreCase(String str1, String str2) {
        return (str1 == null ? str2 == null : str1.equalsIgnoreCase(str2));
    }

    /**
     * <p>
     * Find the first index of any of a set of potential substrings.
     * </p>
     * <p>
     * <code>null</code> String will return <code>-1</code>.
     * </p>
     *
     * @param str the String to check
     * @param searchStrs the Strings to search for
     * @return the first index of any of the searchStrs in str
     * @throws NullPointerException if any of searchStrs[i] is <code>null</code>
     */
    public static int indexOfAny(String str, String[] searchStrs) {
        if ((str == null) || (searchStrs == null)) {
            return -1;
        }
        int sz = searchStrs.length;

        // String's can't have a MAX_VALUEth index.
        int ret = Integer.MAX_VALUE;

        int tmp;
        for (String searchStr : searchStrs) {
            tmp = str.indexOf(searchStr);
            if (tmp == -1) {
                continue;
            }

            if (tmp < ret) {
                ret = tmp;
            }
        }

        return (ret == Integer.MAX_VALUE) ? -1 : ret;
    }

    /**
     * <p>
     * Find the latest index of any of a set of potential substrings.
     * </p>
     * <p>
     * <code>null</code> string will return <code>-1</code>.
     * </p>
     *
     * @param str the String to check
     * @param searchStrs the Strings to search for
     * @return the last index of any of the Strings
     * @throws NullPointerException if any of searchStrs[i] is <code>null</code>
     */
    public static int lastIndexOfAny(String str, String[] searchStrs) {
        if ((str == null) || (searchStrs == null)) {
            return -1;
        }
        int ret = -1;
        int tmp;
        for (String searchStr : searchStrs) {
            tmp = str.lastIndexOf(searchStr);
            if (tmp > ret) {
                ret = tmp;
            }
        }
        return ret;
    }

    // Substring
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Gets a substring from the specified string avoiding exceptions.
     * </p>
     * <p>
     * A negative start position can be used to start <code>n</code> characters from the end of the String.
     * </p>
     *
     * @param str the String to get the substring from
     * @param start the position to start from, negative means count back from the end of the String by this many
     *            characters
     * @return substring from start position
     */
    public static String substring(String str, int start) {
        if (str == null) {
            return null;
        }

        // handle negatives, which means last n characters
        if (start < 0) {
            start = str.length() + start; // remember start is negative
        }

        if (start < 0) {
            start = 0;
        }
        if (start > str.length()) {
            return "";
        }

        return str.substring(start);
    }

    /**
     * <p>
     * Gets a substring from the specified String avoiding exceptions.
     * </p>
     * <p>
     * A negative start position can be used to start/end <code>n</code> characters from the end of the String.
     * </p>
     *
     * @param str the String to get the substring from
     * @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 position
     */
    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()) {
            // check this works.
            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);
    }

    /**
     * <p>
     * Gets the leftmost <code>n</code> characters of a String.
     * </p>
     * <p>
     * If <code>n</code> characters are not available, or the String is <code>null</code>, the String will be returned
     * without an exception.
     * </p>
     *
     * @param str the String to get the leftmost characters from
     * @param len the length of the required String
     * @return the leftmost characters
     * @throws IllegalArgumentException if len is less than zero
     */
    public static String left(String str, int len) {
        if (len < 0) {
            throw new IllegalArgumentException("Requested String length " + len + " is less than zero");
        }
        if ((str == null) || (str.length() <= len)) {
            return str;
        } else {
            return str.substring(0, len);
        }
    }

    /**
     * <p>
     * Gets the rightmost <code>n</code> characters of a String.
     * </p>
     * <p>
     * If <code>n</code> characters are not available, or the String is <code>null</code>, the String will be returned
     * without an exception.
     * </p>
     *
     * @param str the String to get the rightmost characters from
     * @param len the length of the required String
     * @return the leftmost characters
     * @throws IllegalArgumentException if len is less than zero
     */
    public static String right(String str, int len) {
        if (len < 0) {
            throw new IllegalArgumentException("Requested String length " + len + " is less than zero");
        }
        if ((str == null) || (str.length() <= len)) {
            return str;
        } else {
            return str.substring(str.length() - len);
        }
    }

    /**
     * <p>
     * Gets <code>n</code> characters from the middle of a String.
     * </p>
     * <p>
     * If <code>n</code> characters are not available, the remainder of the String will be returned without an
     * exception. If the String is <code>null</code>, <code>null</code> will be returned.
     * </p>
     *
     * @param str the String to get the characters from
     * @param pos the position to start from
     * @param len the length of the required String
     * @return the leftmost characters
     * @throws IndexOutOfBoundsException if pos is out of bounds
     * @throws IllegalArgumentException if len is less than zero
     */
    public static String mid(String str, int pos, int len) {
        if ((pos < 0) || ((str != null) && (pos > str.length()))) {
            throw new StringIndexOutOfBoundsException("String index " + pos + " is out of bounds");
        }
        if (len < 0) {
            throw new IllegalArgumentException("Requested String length " + len + " is less than zero");
        }
        if (str == null) {
            return null;
        }
        if (str.length() <= (pos + len)) {
            return str.substring(pos);
        } else {
            return str.substring(pos, pos + len);
        }
    }

    // Splitting
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Splits the provided text into a array, using whitespace as the separator.
     * </p>
     * <p>
     * The separator is not included in the returned String array.
     * </p>
     *
     * @param str the String to parse
     * @return an array of parsed Strings
     */
    public static String[] split(String str) {
        return split(str, null, -1);
    }

    /**
     * @param text The string to parse.
     * @param separator Characters used as the delimiters. If <code>null</code>, splits on whitespace.
     * @return an array of parsed Strings
     */
    public static String[] split(String text, String separator) {
        return split(text, separator, -1);
    }

    /**
     * <p>
     * Splits the provided text into a array, based on a given separator.
     * </p>
     * <p>
     * The separator is not included in the returned String array. The maximum number of splits to perform can be
     * controlled. A <code>null</code> separator will cause parsing to be on whitespace.
     * </p>
     * <p>
     * This is useful for quickly splitting a String directly into an array of tokens, instead of an enumeration of
     * tokens (as <code>StringTokenizer</code> does).
     * </p>
     *
     * @param str The string to parse.
     * @param separator Characters used as the delimiters. If <code>null</code>, splits on whitespace.
     * @param max The maximum number of elements to include in the array. A zero or negative value implies no limit.
     * @return an array of parsed Strings
     */
    public static String[] split(String str, String separator, int max) {
        StringTokenizer tok;
        if (separator == null) {
            // Null separator means we're using StringTokenizer's default
            // delimiter, which comprises all whitespace characters.
            tok = new StringTokenizer(str);
        } else {
            tok = new StringTokenizer(str, separator);
        }

        int listSize = tok.countTokens();
        if ((max > 0) && (listSize > max)) {
            listSize = max;
        }

        String[] list = new String[listSize];
        int i = 0;
        int lastTokenBegin;
        int lastTokenEnd = 0;
        while (tok.hasMoreTokens()) {
            if ((max > 0) && (i == listSize - 1)) {
                // In the situation where we hit the max yet have
                // tokens left over in our input, the last list
                // element gets all remaining text.
                String endToken = tok.nextToken();
                lastTokenBegin = str.indexOf(endToken, lastTokenEnd);
                list[i] = str.substring(lastTokenBegin);
                break;
            } else {
                list[i] = tok.nextToken();
                lastTokenBegin = str.indexOf(list[i], lastTokenEnd);
                lastTokenEnd = lastTokenBegin + list[i].length();
            }
            i++;
        }
        return list;
    }

    // Joining
    // --------------------------------------------------------------------------
    /**
     * <p>
     * Concatenates elements of an array into a single String.
     * </p>
     * <p>
     * The difference from join is that concatenate has no delimiter.
     * </p>
     *
     * @param array the array of values to concatenate.
     * @return the concatenated string.
     */
    public static String concatenate(Object[] array) {
        return join(array, "");
    }

    /**
     * <p>
     * Joins the elements of the provided array into a single String containing the provided list of elements.
     * </p>
     * <p>
     * No delimiter is added before or after the list. A <code>null</code> separator is the same as a blank String.
     * </p>
     *
     * @param array the array of values to join together
     * @param separator the separator character to use
     * @return the joined String
     */
    public static String join(Object[] array, String separator) {
        if (separator == null) {
            separator = "";
        }
        int arraySize = array.length;
        int bufSize = (arraySize == 0 ? 0 : (array[0].toString().length() + separator.length()) * arraySize);
        StringBuilder buf = new StringBuilder(bufSize);

        for (int i = 0; i < arraySize; i++) {
            if (i > 0) {
                buf.append(separator);
            }
            buf.append(array[i]);
        }
        return buf.toString();
    }

    /**
     * <p>
     * Joins the elements of the provided <code>Iterator</code> into a single String containing the provided elements.
     * </p>
     * <p>
     * No delimiter is added before or after the list. A <code>null</code> separator is the same as a blank String.
     * </p>
     *
     * @param iterator the <code>Iterator</code> of values to join together
     * @param separator the separator character to use
     * @return the joined String
     */
    public static String join(Iterator<?> iterator, String separator) {
        if (separator == null) {
            separator = "";
        }
        StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small
        while (iterator.hasNext()) {
            buf.append(iterator.next());
            if (iterator.hasNext()) {
                buf.append(separator);
            }
        }
        return buf.toString();
    }

    // Replacing
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Replace a char with another char inside a larger String, once.
     * </p>
     * <p>
     * A <code>null</code> reference passed to this method is a no-op.
     * </p>
     *
     * @see #replace(String text, char repl, char with, int max)
     * @param text text to search and replace in
     * @param repl char to search for
     * @param with char to replace with
     * @return the text with any replacements processed
     */
    public static String replaceOnce(String text, char repl, char with) {
        return replace(text, repl, with, 1);
    }

    /**
     * <p>
     * Replace all occurrences of a char within another char.
     * </p>
     * <p>
     * A <code>null</code> reference passed to this method is a no-op.
     * </p>
     *
     * @see #replace(String text, char repl, char with, int max)
     * @param text text to search and replace in
     * @param repl char to search for
     * @param with char to replace with
     * @return the text with any replacements processed
     */
    public static String replace(String text, char repl, char with) {
        return replace(text, repl, with, -1);
    }

    /**
     * <p>
     * Replace a char with another char inside a larger String, for the first <code>max</code> values of the search
     * char.
     * </p>
     * <p>
     * A <code>null</code> reference passed to this method is a no-op.
     * </p>
     *
     * @param text text to search and replace in
     * @param repl char to search for
     * @param with char to replace with
     * @param max maximum number of values to replace, or <code>-1</code> if no maximum
     * @return the text with any replacements processed
     */
    public static String replace(String text, char repl, char with, int max) {
        return replace(text, String.valueOf(repl), String.valueOf(with), max);
    }

    /**
     * <p>
     * Replace a String with another String inside a larger String, once.
     * </p>
     * <p>
     * A <code>null</code> reference passed to this method is a no-op.
     * </p>
     *
     * @see #replace(String text, String repl, String with, int max)
     * @param text text to search and replace in
     * @param repl String to search for
     * @param with String to replace with
     * @return the text with any replacements processed
     */
    public static String replaceOnce(String text, String repl, String with) {
        return replace(text, repl, with, 1);
    }

    /**
     * <p>
     * Replace all occurrences of a String within another String.
     * </p>
     * <p>
     * A <code>null</code> reference passed to this method is a no-op.
     * </p>
     *
     * @see #replace(String text, String repl, String with, int max)
     * @param text text to search and replace in
     * @param repl String to search for
     * @param with String to replace with
     * @return the text with any replacements processed
     */
    public static String replace(String text, String repl, String with) {
        return replace(text, repl, with, -1);
    }

    /**
     * <p>
     * Replace a String with another String inside a larger String, for the first <code>max</code> values of the search
     * String.
     * </p>
     * <p>
     * A <code>null</code> reference passed to this method is a no-op.
     * </p>
     *
     * @param text text to search and replace in
     * @param repl String to search for
     * @param with String to replace with
     * @param max maximum number of values to replace, or <code>-1</code> if no maximum
     * @return the text with any replacements processed
     */
    public static String replace(String text, String repl, String with, int max) {
        if ((text == null) || (repl == null) || (with == null) || (repl.length() == 0)) {
            return text;
        }

        StringBuilder buf = new StringBuilder(text.length());
        int start = 0, end;
        while ((end = text.indexOf(repl, start)) != -1) {
            buf.append(text, start, end).append(with);
            start = end + repl.length();

            if (--max == 0) {
                break;
            }
        }
        buf.append(text, start, text.length());
        return buf.toString();
    }

    /**
     * <p>
     * Overlay a part of a String with another String.
     * </p>
     *
     * @param text String to do overlaying in
     * @param overlay String to overlay
     * @param start int to start overlaying at
     * @param end int to stop overlaying before
     * @return String with overlayed text
     * @throws NullPointerException if text or overlay is <code>null</code>
     */
    public static String overlayString(String text, String overlay, int start, int end) {
        return new StringBuilder(start + overlay.length() + text.length() - end + 1)
                .append(text, 0, start)
                .append(overlay)
                .append(text, end, text.length())
                .toString();
    }

    // Centering
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Center a String in a larger String of size <code>n</code>.
     * </p>
     * <p>
     * Uses spaces as the value to buffer the String with. Equivalent to <code>center(str, size, " ")</code>.
     * </p>
     *
     * @param str String to center
     * @param size int size of new String
     * @return String containing centered String
     * @throws NullPointerException if str is <code>null</code>
     */
    public static String center(String str, int size) {
        return center(str, size, " ");
    }

    /**
     * <p>
     * Center a String in a larger String of size <code>n</code>.
     * </p>
     * <p>
     * Uses a supplied String as the value to buffer the String with.
     * </p>
     *
     * @param str String to center
     * @param size int size of new String
     * @param delim String to buffer the new String with
     * @return String containing centered String
     * @throws NullPointerException if str or delim is <code>null</code>
     * @throws ArithmeticException if delim is the empty String
     */
    public static String center(String str, int size, String delim) {
        int sz = str.length();
        int p = size - sz;
        if (p < 1) {
            return str;
        }
        str = leftPad(str, sz + p / 2, delim);
        str = rightPad(str, size, delim);
        return str;
    }

    // Chomping
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Remove the last newline, and everything after it from a String.
     * </p>
     *
     * @param str String to chomp the newline from
     * @return String without chomped newline
     * @throws NullPointerException if str is <code>null</code>
     */
    public static String chomp(String str) {
        return chomp(str, "\n");
    }

    /**
     * <p>
     * Remove the last value of a supplied String, and everything after it from a String.
     * </p>
     *
     * @param str String to chomp from
     * @param sep String to chomp
     * @return String without chomped ending
     * @throws NullPointerException if str or sep is <code>null</code>
     */
    public static String chomp(String str, String sep) {
        int idx = str.lastIndexOf(sep);
        if (idx != -1) {
            return str.substring(0, idx);
        } else {
            return str;
        }
    }

    /**
     * <p>
     * Remove a newline if and only if it is at the end of the supplied String.
     * </p>
     *
     * @param str String to chomp from
     * @return String without chomped ending
     * @throws NullPointerException if str is <code>null</code>
     */
    public static String chompLast(String str) {
        return chompLast(str, "\n");
    }

    /**
     * <p>
     * Remove a value if and only if the String ends with that value.
     * </p>
     *
     * @param str String to chomp from
     * @param sep String to chomp
     * @return String without chomped ending
     * @throws NullPointerException if str or sep is <code>null</code>
     */
    public static String chompLast(String str, String sep) {
        if (str.length() == 0) {
            return str;
        }
        String sub = str.substring(str.length() - sep.length());
        if (sep.equals(sub)) {
            return str.substring(0, str.length() - sep.length());
        } else {
            return str;
        }
    }

    /**
     * <p>
     * Remove everything and return the last value of a supplied String, and everything after it from a String.
     * </p>
     *
     * @param str String to chomp from
     * @param sep String to chomp
     * @return String chomped
     * @throws NullPointerException if str or sep is <code>null</code>
     */
    public static String getChomp(String str, String sep) {
        int idx = str.lastIndexOf(sep);
        if (idx == str.length() - sep.length()) {
            return sep;
        } else if (idx != -1) {
            return str.substring(idx);
        } else {
            return "";
        }
    }

    /**
     * <p>
     * Remove the first value of a supplied String, and everything before it from a String.
     * </p>
     *
     * @param str String to chomp from
     * @param sep String to chomp
     * @return String without chomped beginning
     * @throws NullPointerException if str or sep is <code>null</code>
     */
    public static String prechomp(String str, String sep) {
        int idx = str.indexOf(sep);
        if (idx != -1) {
            return str.substring(idx + sep.length());
        } else {
            return str;
        }
    }

    /**
     * <p>
     * Remove and return everything before the first value of a supplied String from another String.
     * </p>
     *
     * @param str String to chomp from
     * @param sep String to chomp
     * @return String prechomped
     * @throws NullPointerException if str or sep is <code>null</code>
     */
    public static String getPrechomp(String str, String sep) {
        int idx = str.indexOf(sep);
        if (idx != -1) {
            return str.substring(0, idx + sep.length());
        } else {
            return "";
        }
    }

    // Chopping
    // --------------------------------------------------------------------------

    /**
     * <p>
     * Remove the last character from a String.
     * </p>
     * <p>
     * If the String ends in <code>\r\n</code>, then remove both of them.
     * </p>
     *
     * @param str String to chop last character from
     * @return String without last character
     * @throws NullPointerException if str is <code>null</code>
     */
    public static String chop(String str) {
        if ("".equals(str)) {
            return "";
        }
        if (str.length() == 1) {
            return "";
        }
        int lastIdx = str.length() - 1;
         String ret = str.substring(0, lastIdx);
         char last = str.charAt(lastIdx);
         if (last == '\n') {
             if (ret.charAt(lastIdx - 1) == '\r') {
                 return ret.substring(0, lastIdx - 1);
             }
         }
         return ret;
     }

     /**
      * <p>
      * Remove <code>\n</code> from end of a String if it's there. If a <code>\r</code> precedes it, then remove that
      * too.
      * </p>
      *
      * @param str String to chop a newline from
      * @return String without newline
      * @throws NullPointerException if str is <code>null</code>
      */
     public static String chopNewline(String str) {
         int lastIdx = str.length() - 1;
         char last = str.charAt(lastIdx);
         if (last == '\n') {
             if (str.charAt(lastIdx - 1) == '\r') {
                 lastIdx--;
             }
         } else {
             lastIdx++;
         }
         return str.substring(0, lastIdx);
     }

     // Conversion
     // --------------------------------------------------------------------------

     // spec 3.10.6
     /**
      * <p>
      * Escapes any values it finds into their String form.
      * </p>
      * <p>
      * So a tab becomes the characters <code>'\\'</code> and <code>'t'</code>.
      * </p>
      *
      * @param str String to escape values in
      * @return String with escaped values
      * @throws NullPointerException if str is <code>null</code>
      */
     public static String escape(String str) {
         // improved with code from cybertiger@cyberiantiger.org
         // unicode from him, and default for < 32's.
         int sz = str.length();
         StringBuilder buffer = new StringBuilder(2 * sz);
         for (int i = 0; i < sz; i++) {
             char ch = str.charAt(i);

             // handle unicode
             if (ch > 0xfff) {
                 buffer.append("\\u" + Integer.toHexString(ch));
             } else if (ch > 0xff) {
                 buffer.append("\\u0" + Integer.toHexString(ch));
             } else if (ch > 0x7f) {
                 buffer.append("\\u00" + Integer.toHexString(ch));
             } else if (ch < 32) {
                 switch (ch) {
                     case '\b':
                         buffer.append('\\');
                         buffer.append('b');
                         break;
                     case '\n':
                         buffer.append('\\');
                         buffer.append('n');
                         break;
                     case '\t':
                         buffer.append('\\');
                         buffer.append('t');
                         break;
                     case '\f':
                         buffer.append('\\');
                         buffer.append('f');
                         break;
                     case '\r':
                         buffer.append('\\');
                         buffer.append('r');
                         break;
                     default:
                         if (ch > 0xf) {
                             buffer.append("\\u00" + Integer.toHexString(ch));
                         } else {
                             buffer.append("\\u000" + Integer.toHexString(ch));
                         }
                         break;
                 }
             } else {
                 switch (ch) {
                     case '\'':
                         buffer.append('\\');
                         buffer.append('\'');
                         break;
                     case '"':
                         buffer.append('\\');
                         buffer.append('"');
                         break;
                     case '\\':
                         buffer.append('\\');
                         buffer.append('\\');
                         break;
                     default:
                         buffer.append(ch);
                         break;
                 }
             }
         }
         return buffer.toString();
     }

     // Padding
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Repeat a String <code>n</code> times to form a new string.
      * </p>
      *
      * @param str String to repeat
      * @param repeat number of times to repeat str
      * @return String with repeated String
      * @throws NegativeArraySizeException if <code>repeat &lt; 0</code>
      * @throws NullPointerException if str is <code>null</code>
      */
     public static String repeat(String str, int repeat) {
         StringBuilder buffer = new StringBuilder(repeat * str.length());
         for (int i = 0; i < repeat; i++) {
             buffer.append(str);
         }
         return buffer.toString();
     }

     /**
      * <p>
      * Right pad a String with spaces.
      * </p>
      * <p>
      * The String is padded to the size of <code>n</code>.
      * </p>
      *
      * @param str String to repeat
      * @param size number of times to repeat str
      * @return right padded String
      * @throws NullPointerException if str is <code>null</code>
      */
     public static String rightPad(String str, int size) {
         return rightPad(str, size, " ");
     }

     /**
      * <p>
      * Right pad a String with a specified string.
      * </p>
      * <p>
      * The String is padded to the size of <code>n</code>.
      * </p>
      *
      * @param str String to pad out
      * @param size size to pad to
      * @param delim String to pad with
      * @return right padded String
      * @throws NullPointerException if str or delim is <code>null</code>
      * @throws ArithmeticException if delim is the empty String
      */
     public static String rightPad(String str, int size, String delim) {
         size = (size - str.length()) / delim.length();
         if (size > 0) {
             str += repeat(delim, size);
         }
         return str;
     }

     /**
      * <p>
      * Left pad a String with spaces.
      * </p>
      * <p>
      * The String is padded to the size of <code>n</code>.
      * </p>
      *
      * @param str String to pad out
      * @param size size to pad to
      * @return left padded String
      * @throws NullPointerException if str or delim is <code>null</code>
      */
     public static String leftPad(String str, int size) {
         return leftPad(str, size, " ");
     }

     /**
      * Left pad a String with a specified string. Pad to a size of n.
      *
      * @param str String to pad out
      * @param size size to pad to
      * @param delim String to pad with
      * @return left padded String
      * @throws NullPointerException if str or delim is null
      * @throws ArithmeticException if delim is the empty string
      */
     public static String leftPad(String str, int size, String delim) {
         size = (size - str.length()) / delim.length();
         if (size > 0) {
             str = repeat(delim, size) + str;
         }
         return str;
     }

     // Stripping
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Remove whitespace from the front and back of a String.
      * </p>
      *
      * @param str the String to remove whitespace from
      * @return the stripped String
      */
     public static String strip(String str) {
         return strip(str, null);
     }

     /**
      * <p>
      * Remove a specified String from the front and back of a String.
      * </p>
      * <p>
      * If whitespace is wanted to be removed, used the {@link #strip(java.lang.String)} method.
      * </p>
      *
      * @param str the String to remove a string from
      * @param delim the String to remove at start and end
      * @return the stripped String
      */
     public static String strip(String str, String delim) {
         str = stripStart(str, delim);
         return stripEnd(str, delim);
     }

     /**
      * <p>
      * Strip whitespace from the front and back of every String in the array.
      * </p>
      *
      * @param strs the Strings to remove whitespace from
      * @return the stripped Strings
      */
     public static String[] stripAll(String[] strs) {
         return stripAll(strs, null);
     }

     /**
      * <p>
      * Strip the specified delimiter from the front and back of every String in the array.
      * </p>
      *
      * @param strs the Strings to remove a String from
      * @param delimiter the String to remove at start and end
      * @return the stripped Strings
      */
     public static String[] stripAll(String[] strs, String delimiter) {
         if ((strs == null) || (strs.length == 0)) {
             return strs;
         }
         int sz = strs.length;
         String[] newArr = new String[sz];
         for (int i = 0; i < sz; i++) {
             newArr[i] = strip(strs[i], delimiter);
         }
         return newArr;
     }

     /**
      * <p>
      * Strip any of a supplied String from the end of a String.
      * </p>
      * <p>
      * If the strip String is <code>null</code>, whitespace is stripped.
      * </p>
      *
      * @param str the String to remove characters from
      * @param strip the String to remove
      * @return the stripped String
      */
     public static String stripEnd(String str, String strip) {
         if (str == null) {
             return null;
         }
         int end = str.length();

         if (strip == null) {
             while ((end != 0) && Character.isWhitespace(str.charAt(end - 1))) {
                 end--;
             }
         } else {
             while ((end != 0) && (strip.indexOf(str.charAt(end - 1)) != -1)) {
                 end--;
             }
         }
         return str.substring(0, end);
     }

     /**
      * <p>
      * Strip any of a supplied String from the start of a String.
      * </p>
      * <p>
      * If the strip String is <code>null</code>, whitespace is stripped.
      * </p>
      *
      * @param str the String to remove characters from
      * @param strip the String to remove
      * @return the stripped String
      */
     public static String stripStart(String str, String strip) {
         if (str == null) {
             return null;
         }

         int start = 0;

         int sz = str.length();

         if (strip == null) {
             while ((start != sz) && Character.isWhitespace(str.charAt(start))) {
                 start++;
             }
         } else {
             while ((start != sz) && (strip.indexOf(str.charAt(start)) != -1)) {
                 start++;
             }
         }
         return str.substring(start);
     }

     // Case conversion
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Convert a String to upper case, <code>null</code> String returns <code>null</code>.
      * </p>
      *
      * @param str the String to uppercase
      * @return the upper cased String
      */
     public static String upperCase(String str) {
         if (str == null) {
             return null;
         }
         return str.toUpperCase();
     }

     /**
      * <p>
      * Convert a String to lower case, <code>null</code> String returns <code>null</code>.
      * </p>
      *
      * @param str the string to lowercase
      * @return the lower cased String
      */
     public static String lowerCase(String str) {
         if (str == null) {
             return null;
         }
         return str.toLowerCase();
     }

     /**
      * <p>
      * Uncapitalise a String.
      * </p>
      * <p>
      * That is, convert the first character into lower-case. <code>null</code> is returned as <code>null</code>.
      * </p>
      *
      * @param str the String to uncapitalise
      * @return uncapitalised String
      */
     public static String uncapitalise(String str) {
         if (str == null) {
             return null;
         } else if (str.length() == 0) {
             return "";
         } else {
             return new StringBuilder(str.length())
                     .append(Character.toLowerCase(str.charAt(0)))
                     .append(str, 1, str.length())
                     .toString();
         }
     }

     /**
      * <p>
      * Capitalise a String.
      * </p>
      * <p>
      * That is, convert the first character into title-case. <code>null</code> is returned as <code>null</code>.
      * </p>
      *
      * @param str the String to capitalise
      * @return capitalised String
      */
     public static String capitalise(String str) {
         if (str == null) {
             return null;
         } else if (str.length() == 0) {
             return "";
         } else {
             return new StringBuilder(str.length())
                     .append(Character.toTitleCase(str.charAt(0)))
                     .append(str, 1, str.length())
                     .toString();
         }
     }

     /**
      * <p>
      * Swaps the case of String.
      * </p>
      * <p>
      * Properly looks after making sure the start of words are Titlecase and not Uppercase.
      * </p>
      * <p>
      * <code>null</code> is returned as <code>null</code>.
      * </p>
      *
      * @param str the String to swap the case of
      * @return the modified String
      */
     public static String swapCase(String str) {
         if (str == null) {
             return null;
         }
         int sz = str.length();
         StringBuilder buffer = new StringBuilder(sz);

         boolean whitespace = false;
         char ch;
         char tmp;

         for (int i = 0; i < sz; i++) {
             ch = str.charAt(i);
             if (Character.isUpperCase(ch)) {
                 tmp = Character.toLowerCase(ch);
             } else if (Character.isTitleCase(ch)) {
                 tmp = Character.toLowerCase(ch);
             } else if (Character.isLowerCase(ch)) {
                 if (whitespace) {
                     tmp = Character.toTitleCase(ch);
                 } else {
                     tmp = Character.toUpperCase(ch);
                 }
             } else {
                 tmp = ch;
             }
             buffer.append(tmp);
             whitespace = Character.isWhitespace(ch);
         }
         return buffer.toString();
     }

     /**
      * <p>
      * Capitalise all the words in a String.
      * </p>
      * <p>
      * Uses {@link Character#isWhitespace(char)} as a separator between words.
      * </p>
      * <p>
      * <code>null</code> will return <code>null</code>.
      * </p>
      *
      * @param str the String to capitalise
      * @return capitalised String
      */
     public static String capitaliseAllWords(String str) {
         if (str == null) {
             return null;
         }
         int sz = str.length();
         StringBuilder buffer = new StringBuilder(sz);
         boolean space = true;
         for (int i = 0; i < sz; i++) {
             char ch = str.charAt(i);
             if (Character.isWhitespace(ch)) {
                 buffer.append(ch);
                 space = true;
             } else if (space) {
                 buffer.append(Character.toTitleCase(ch));
                 space = false;
             } else {
                 buffer.append(ch);
             }
         }
         return buffer.toString();
     }

     /**
      * <p>
      * Uncapitalise all the words in a string.
      * </p>
      * <p>
      * Uses {@link Character#isWhitespace(char)} as a separator between words.
      * </p>
      * <p>
      * <code>null</code> will return <code>null</code>.
      * </p>
      *
      * @param str the string to uncapitalise
      * @return uncapitalised string
      */
     public static String uncapitaliseAllWords(String str) {
         if (str == null) {
             return null;
         }
         int sz = str.length();
         StringBuilder buffer = new StringBuilder(sz);
         boolean space = true;
         for (int i = 0; i < sz; i++) {
             char ch = str.charAt(i);
             if (Character.isWhitespace(ch)) {
                 buffer.append(ch);
                 space = true;
             } else if (space) {
                 buffer.append(Character.toLowerCase(ch));
                 space = false;
             } else {
                 buffer.append(ch);
             }
         }
         return buffer.toString();
     }

     // Nested extraction
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Get the String that is nested in between two instances of the same String.
      * </p>
      * <p>
      * If <code>str</code> is <code>null</code>, will return <code>null</code>.
      * </p>
      *
      * @param str the String containing nested-string
      * @param tag the String before and after nested-string
      * @return the String that was nested, or <code>null</code>
      * @throws NullPointerException if tag is <code>null</code>
      */
     public static String getNestedString(String str, String tag) {
         return getNestedString(str, tag, tag);
     }

     /**
      * <p>
      * Get the String that is nested in between two Strings.
      * </p>
      *
      * @param str the String containing nested-string
      * @param open the String before nested-string
      * @param close the String after nested-string
      * @return the String that was nested, or <code>null</code>
      * @throws NullPointerException if open or close is <code>null</code>
      */
     public static String getNestedString(String str, String open, String close) {
         if (str == null) {
             return null;
         }
         int start = str.indexOf(open);
         if (start != -1) {
             int end = str.indexOf(close, start + open.length());
             if (end != -1) {
                 return str.substring(start + open.length(), end);
             }
         }
         return null;
     }

     /**
      * <p>
      * How many times is the substring in the larger String.
      * </p>
      * <p>
      * <code>null</code> returns <code>0</code>.
      * </p>
      *
      * @param str the String to check
      * @param sub the substring to count
      * @return the number of occurrences, 0 if the String is <code>null</code>
      * @throws NullPointerException if sub is <code>null</code>
      */
     public static int countMatches(String str, String sub) {
         if (sub.equals("")) {
             return 0;
         }
         if (str == null) {
             return 0;
         }
         int count = 0;
         int idx = 0;
         while ((idx = str.indexOf(sub, idx)) != -1) {
             count++;
             idx += sub.length();
         }
         return count;
     }

     // Character Tests
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Checks if the String contains only unicode letters.
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains letters, and is non-null
      */
     public static boolean isAlpha(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if (Character.isLetter(str.charAt(i)) == false) {
                 return false;
             }
         }
         return true;
     }

     /**
      * <p>
      * Checks if the String contains only whitespace.
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains whitespace, and is non-null
      */
     public static boolean isWhitespace(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if ((Character.isWhitespace(str.charAt(i)) == false)) {
                 return false;
             }
         }
         return true;
     }

     /**
      * <p>
      * Checks if the String contains only unicode letters and space (<code>' '</code>).
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains letters and space, and is non-null
      */
     public static boolean isAlphaSpace(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if ((Character.isLetter(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
                 return false;
             }
         }
         return true;
     }

     /**
      * <p>
      * Checks if the String contains only unicode letters or digits.
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains letters or digits, and is non-null
      */
     public static boolean isAlphanumeric(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if (Character.isLetterOrDigit(str.charAt(i)) == false) {
                 return false;
             }
         }
         return true;
     }

     /**
      * <p>
      * Checks if the String contains only unicode letters, digits or space (<code>' '</code>).
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains letters, digits or space, and is non-null
      */
     public static boolean isAlphanumericSpace(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if ((Character.isLetterOrDigit(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
                 return false;
             }
         }
         return true;
     }

     /**
      * <p>
      * Checks if the String contains only unicode digits.
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains digits, and is non-null
      */
     public static boolean isNumeric(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if (Character.isDigit(str.charAt(i)) == false) {
                 return false;
             }
         }
         return true;
     }

     /**
      * <p>
      * Checks if the String contains only unicode digits or space (<code>' '</code>).
      * </p>
      * <p>
      * <code>null</code> will return <code>false</code>. An empty String will return <code>true</code>.
      * </p>
      *
      * @param str the String to check
      * @return <code>true</code> if only contains digits or space, and is non-null
      */
     public static boolean isNumericSpace(String str) {
         if (str == null) {
             return false;
         }
         int sz = str.length();
         for (int i = 0; i < sz; i++) {
             if ((Character.isDigit(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
                 return false;
             }
         }
         return true;
     }

     // Defaults
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Returns either the passed in <code>Object</code> as a String, or, if the <code>Object</code> is
      * <code>null</code>, an empty String.
      * </p>
      *
      * @param obj the Object to check
      * @return the passed in Object's toString, or blank if it was <code>null</code>
      * @see Objects#toString(Object, String)
      */
     @Deprecated
     public static String defaultString(Object obj) {
         return defaultString(obj, "");
     }

     /**
      * <p>
      * Returns either the passed in <code>Object</code> as a String, or, if the <code>Object</code> is
      * <code>null</code>, a passed in default String.
      * </p>
      *
      * @param obj the Object to check
      * @param defaultString the default String to return if str is <code>null</code>
      * @return the passed in string, or the default if it was <code>null</code>
      * @see Objects#toString(Object, String)
      */
     @Deprecated
     public static String defaultString(Object obj, String defaultString) {
         return Objects.toString(obj, defaultString);
     }

     // Reversing
     // --------------------------------------------------------------------------

     /**
      * <p>
      * Reverse a String.
      * </p>
      * <p>
      * <code>null</code> String returns <code>null</code>.
      * </p>
      *
      * @param str the String to reverse
      * @return the reversed String
      */
     public static String reverse(String str) {
         if (str == null) {
             return null;
         }
         return new StringBuilder(str).reverse().toString();
     }

     /**
      * <p>
      * Reverses a String that is delimited by a specific character.
      * </p>
      * <p>
      * The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the
      * delimiter is <code>'.'</code>).
      * </p>
      *
      * @param str the String to reverse
      * @param delimiter the delimiter to use
      * @return the reversed String
      */
     public static String reverseDelimitedString(String str, String delimiter) {
         // could implement manually, but simple way is to reuse other,
         // probably slower, methods.
         String[] strs = split(str, delimiter);
         reverseArray(strs);
         return join(strs, delimiter);
     }

     /**
      * <p>
      * Reverses an array.
      * </p>
      * <p>
      * TAKEN FROM CollectionsUtils.
      * </p>
      *
      * @param array the array to reverse
      */
     private static void reverseArray(Object[] array) {
         int i = 0;
         int j = array.length - 1;
         Object tmp;

         while (j > i) {
             tmp = array[j];
             array[j] = array[i];
             array[i] = tmp;
             j--;
             i++;
         }
     }

     // Abbreviating
     // --------------------------------------------------------------------------

     /**
      * @return Turn "Now is the time for all good men" into "Now is the time for..."
      * <p>
      * Specifically:
      * <p>
      * If str is less than max characters long, return it. Else abbreviate it to (substring(str, 0, max-3) + "..."). If
      * maxWidth is less than 3, throw an IllegalArgumentException. In no case will it return a string of length greater
      * than maxWidth.
      * @param s string
      * @param maxWidth maximum length of result string
      **/
     public static String abbreviate(String s, int maxWidth) {
         return abbreviate(s, 0, maxWidth);
     }

     /**
      * @return Turn "Now is the time for all good men" into "...is the time for..."
      *
      * Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is
      * not necessarily going to be the leftmost character in the result, or the first character following the ellipses,
      * but it will appear somewhere in the result. In no case will it return a string of length greater than maxWidth.
      * @param s string
      * @param offset left edge of source string
      * @param maxWidth maximum length of result string
      **/
     public static String abbreviate(String s, int offset, int maxWidth) {
         if (maxWidth < 4) {
             throw new IllegalArgumentException("Minimum abbreviation width is 4");
         }
         if (s.length() <= maxWidth) {
             return s;
         }
         if (offset > s.length()) {
             offset = s.length();
         }
         if ((s.length() - offset) < (maxWidth - 3)) {
             offset = s.length() - (maxWidth - 3);
         }
         if (offset <= 4) {
             return s.substring(0, maxWidth - 3) + "...";
         }
         if (maxWidth < 7) {
             throw new IllegalArgumentException("Minimum abbreviation width with offset is 7");
         }
         if ((offset + (maxWidth - 3)) < s.length()) {
             return "..." + abbreviate(s.substring(offset), maxWidth - 3);
         }
         return "..." + s.substring(s.length() - (maxWidth - 3));
     }

     // Difference
     // --------------------------------------------------------------------------

     /**
      * Compare two strings, and return the portion where they differ. (More precisely, return the remainder of the
      * second string, starting from where it's different from the first.)
      * <p>
      * E.g. strdiff("i am a machine", "i am a robot") -&gt; "robot"
      * @param s1 string
      * @param s2 string
      * @return the portion of s2 where it differs from s1; returns the empty string ("") if they are equal
      **/
     public static String difference(String s1, String s2) {
         int at = differenceAt(s1, s2);
         if (at == -1) {
             return "";
         }
         return s2.substring(at);
     }

     /**
      * Compare two strings, and return the index at which the strings begin to differ.
      * <p>
      * E.g. strdiff("i am a machine", "i am a robot") -&gt; 7
      * </p>
      * @param s1 string
      * @param s2 string
      * @return the index where s2 and s1 begin to differ; -1 if they are equal
      **/
     public static int differenceAt(String s1, String s2) {
         int i;
         for (i = 0; (i < s1.length()) && (i < s2.length()); ++i) {
             if (s1.charAt(i) != s2.charAt(i)) {
                 break;
             }
         }
         if ((i < s2.length()) || (i < s1.length())) {
             return i;
         }
         return -1;
     }

     public static String interpolate(String text, Map<?, ?> namespace) {
         Iterator<?> keys = namespace.keySet().iterator();

         while (keys.hasNext()) {
             String key = keys.next().toString();

             Object obj = namespace.get(key);

             if (obj == null) {
                 throw new NullPointerException("The value of the key '" + key + "' is null.");
             }

             String value = obj.toString();

             text = replace(text, "${" + key + "}", value);

             if (!key.contains(" ")) {
                 text = replace(text, "$" + key, value);
             }
         }
         return text;
     }

     public static String removeAndHump(String data, String replaceThis) {
         String temp;

         StringBuilder out = new StringBuilder();

         temp = data;

         StringTokenizer st = new StringTokenizer(temp, replaceThis);

         while (st.hasMoreTokens()) {
             String element = (String) st.nextElement();

             out.append(capitalizeFirstLetter(element));
         }

         return out.toString();
     }

     public static String capitalizeFirstLetter(String data) {
         char firstLetter = Character.toTitleCase(data.substring(0, 1).charAt(0));

         String restLetters = data.substring(1);

         return firstLetter + restLetters;
     }

     public static String lowercaseFirstLetter(String data) {
         char firstLetter = Character.toLowerCase(data.substring(0, 1).charAt(0));

         String restLetters = data.substring(1);

         return firstLetter + restLetters;
     }

     public static String addAndDeHump(String view) {
         StringBuilder sb = new StringBuilder();

         for (int i = 0; i < view.length(); i++) {
             if ((i != 0) && Character.isUpperCase(view.charAt(i))) {
                 sb.append('-');
             }

             sb.append(view.charAt(i));
         }

         return sb.toString().trim().toLowerCase(Locale.ENGLISH);
     }

     /**
      * <p>
      * Quote and escape a String with the given character, handling <code>null</code>.
      * </p>
      *
      * <pre>
      * StringUtils.quoteAndEscape(null, *)    = null
      * StringUtils.quoteAndEscape("", *)      = ""
      * StringUtils.quoteAndEscape("abc", '"') = abc
      * StringUtils.quoteAndEscape("a\"bc", '"') = "a\"bc"
      * StringUtils.quoteAndEscape("a\"bc", '\'') = 'a\"bc'
      * </pre>
      *
      * @param source the source String
      * @param quoteChar the char used to quote
      * @return the String quoted and escaped
      * @since 1.5.1
      * @see #quoteAndEscape(String, char, char[], char[], char, boolean)
      */
     public static String quoteAndEscape(String source, char quoteChar) {
         return quoteAndEscape(source, quoteChar, new char[] {quoteChar}, new char[] {' '}, '\\', false);
     }

     /**
      * <p>
      * Quote and escape a String with the given character, handling <code>null</code>.
      * </p>
      *
      * @param source the source String
      * @param quoteChar the char used to quote
      * @param quotingTriggers chars generating a quote
      * @return the String quoted and escaped
      * @since 1.5.1
      * @see #quoteAndEscape(String, char, char[], char[], char, boolean)
      */
     public static String quoteAndEscape(String source, char quoteChar, char[] quotingTriggers) {
         return quoteAndEscape(source, quoteChar, new char[] {quoteChar}, quotingTriggers, '\\', false);
     }

     /**
      * @param source the source String
      * @param quoteChar the char used to quote
      * @param escapedChars chars to escape
      * @param escapeChar char used for escaping
      * @param force force the quoting
      * @return the String quoted and escaped
      * @since 1.5.1
      * @see #quoteAndEscape(String, char, char[], char[], char, boolean)
      */
     public static String quoteAndEscape(
             String source, char quoteChar, final char[] escapedChars, char escapeChar, boolean force) {
         return quoteAndEscape(source, quoteChar, escapedChars, new char[] {' '}, escapeChar, force);
     }

     /**
      * @param source the source String
      * @param quoteChar the char used to quote
      * @param escapedChars chars to escape
      * @param quotingTriggers chars generating a quote
      * @param escapeChar char used for escaping
      * @param force force the quoting
      * @return the String quoted and escaped
      * @since 1.5.1
      */
     public static String quoteAndEscape(
             String source,
             char quoteChar,
             final char[] escapedChars,
             final char[] quotingTriggers,
             char escapeChar,
             boolean force) {
         return quoteAndEscape(source, quoteChar, escapedChars, quotingTriggers, escapeChar + "%s", force);
     }

     /**
      * @param source the source String
      * @param quoteChar the char used to quote
      * @param escapedChars chars to escape
      * @param quotingTriggers chars generating a quote
      * @param escapePattern pattern used for escaping
      * @param force force the quoting
      * @return the String quoted and escaped
      * @since 3.0.4
      */
     public static String quoteAndEscape(
             String source,
             char quoteChar,
             final char[] escapedChars,
             final char[] quotingTriggers,
             String escapePattern,
             boolean force) {
         if (source == null) {
             return null;
         }

         if (!force
                 && source.startsWith(Character.toString(quoteChar))
                 && source.endsWith(Character.toString(quoteChar))) {
             return source;
         }

         String escaped = escape(source, escapedChars, escapePattern);

         boolean quote = false;
         if (force) {
             quote = true;
         } else if (!escaped.equals(source)) {
             quote = true;
         } else {
             for (char quotingTrigger : quotingTriggers) {
                 if (escaped.indexOf(quotingTrigger) > -1) {
                     quote = true;
                     break;
                 }
             }
         }

         if (quote) {
             return quoteChar + escaped + quoteChar;
         }

         return escaped;
     }

     /**
      * @param source the source String
      * @param escapedChars chars to escape
      * @param escapeChar char used for escaping
      * @return the String escaped
      * @since 1.5.1
      */
     public static String escape(String source, final char[] escapedChars, char escapeChar) {
         return escape(source, escapedChars, escapeChar + "%s");
     }

     /**
      * @param source the source String
      * @param escapedChars chars to escape
      * @param escapePattern pattern used for escaping
      * @return the String escaped
      * @since 3.0.4
      */
     public static String escape(String source, final char[] escapedChars, String escapePattern) {
         if (source == null) {
             return null;
         }

         char[] eqc = new char[escapedChars.length];
         System.arraycopy(escapedChars, 0, eqc, 0, escapedChars.length);
         Arrays.sort(eqc);

         StringBuilder buffer = new StringBuilder(source.length());

         for (int i = 0; i < source.length(); i++) {
             final char c = source.charAt(i);
             int result = Arrays.binarySearch(eqc, c);

             if (result > -1) {
                 buffer.append(String.format(escapePattern, c));
             } else {
                 buffer.append(c);
             }
         }

         return buffer.toString();
     }

     /**
      * Remove all duplicate whitespace characters and line terminators are replaced with a single space.
      *
      * @param s a not null String
      * @return a string with unique whitespace.
      * @since 1.5.7
      */
     public static String removeDuplicateWhitespace(String s) {
         StringBuilder result = new StringBuilder();
         int length = s.length();
         boolean isPreviousWhiteSpace = false;
         for (int i = 0; i < length; i++) {
             char c = s.charAt(i);
             boolean thisCharWhiteSpace = Character.isWhitespace(c);
             if (!(isPreviousWhiteSpace && thisCharWhiteSpace)) {
                 result.append(c);
             }
             isPreviousWhiteSpace = thisCharWhiteSpace;
         }
         return result.toString();
     }

     /**
      * Parses the given String and replaces all occurrences of '\n', '\r' and '\r\n' with the system line separator.
      *
      * @param s a not null String
      * @return a String that contains only System line separators.
      * @see #unifyLineSeparators(String, String)
      * @since 1.5.7
      */
     public static String unifyLineSeparators(String s) {
         return unifyLineSeparators(s, System.getProperty("line.separator"));
     }

     /**
      * Parses the given String and replaces all occurrences of '\n', '\r' and '\r\n' with the system line separator.
      *
      * @param s a not null String
      * @param ls the wanted line separator ("\n" on UNIX), if null using the System line separator.
      * @return a String that contains only System line separators.
      * @throws IllegalArgumentException if ls is not '\n', '\r' and '\r\n' characters.
      * @since 1.5.7
      */
     public static String unifyLineSeparators(String s, String ls) {
         if (s == null) {
             return null;
         }

         if (ls == null) {
             ls = System.getProperty("line.separator");
         }

         if (!(ls.equals("\n") || ls.equals("\r") || ls.equals("\r\n"))) {
             throw new IllegalArgumentException("Requested line separator is invalid.");
         }

         int length = s.length();

         StringBuilder buffer = new StringBuilder(length);
         for (int i = 0; i < length; i++) {
             if (s.charAt(i) == '\r') {
                 if ((i + 1) < length && s.charAt(i + 1) == '\n') {
                     i++;
                 }

                 buffer.append(ls);
             } else if (s.charAt(i) == '\n') {
                 buffer.append(ls);
             } else {
                 buffer.append(s.charAt(i));
             }
         }

         return buffer.toString();
     }

     /**
      * <p>
      * Checks if String contains a search character, handling <code>null</code>. This method uses
      * {@link String#indexOf(int)}.
      * </p>
      * <p>
      * A <code>null</code> or empty ("") String will return <code>false</code>.
      * </p>
      *
      * <pre>
      * StringUtils.contains(null, *)    = false
      * StringUtils.contains("", *)      = false
      * StringUtils.contains("abc", 'a') = true
      * StringUtils.contains("abc", 'z') = false
      * </pre>
      *
      * @param str the String to check, may be null
      * @param searchChar the character to find
      * @return true if the String contains the search character, false if not or <code>null</code> string input
      * @since 1.5.7
      */
     public static boolean contains(String str, char searchChar) {
         if (isEmpty(str)) {
             return false;
         }
         return str.indexOf(searchChar) >= 0;
     }

     /**
      * <p>
      * Checks if String contains a search String, handling <code>null</code>. This method uses
      * {@link String#indexOf(int)}.
      * </p>
      * <p>
      * A <code>null</code> String will return <code>false</code>.
      * </p>
      *
      * <pre>
      * StringUtils.contains(null, *)     = false
      * StringUtils.contains(*, null)     = false
      * StringUtils.contains("", "")      = true
      * StringUtils.contains("abc", "")   = true
      * StringUtils.contains("abc", "a")  = true
      * StringUtils.contains("abc", "z")  = false
      * </pre>
      *
      * @param str the String to check, may be null
      * @param searchStr the String to find, may be null
      * @return true if the String contains the search String, false if not or <code>null</code> string input
      * @since 1.5.7
      */
     public static boolean contains(String str, String searchStr) {
         if (str == null || searchStr == null) {
             return false;
         }
         return str.contains(searchStr);
     }
 }