stringutils.java

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     * To strip whitespace use {@link #strip(String)}.</p>
     * 
     * <p>To trim your choice of characters, use the
     * {@link #strip(String, String)} methods.</p>
     * 
     * <pre>
     * StringUtils.trim(null)          = null
     * StringUtils.trim("")            = ""
     * StringUtils.trim("     ")       = ""
     * StringUtils.trim("abc")         = "abc"
     * StringUtils.trim("    abc    ") = "abc"
     * </pre>
     *
     * @param str  the String to be trimmed, may be null
     * @return the trimmed string, <code>null</code> if null String input
     */
    public static String trim(String str) {
        return (str == null ? null : str.trim());
    }

    /** 
     * <p>Removes control characters (char &lt;= 32) from both  
     * ends of this String returning <code>null</code> if the String is 
     * empty ("") after the trim or if it is <code>null</code>.
     * 
     * <p>The String is trimmed using {@link String#trim()}.
     * Trim removes start and end characters &lt;= 32.
     * To strip whitespace use {@link #stripToNull(String)}.</p>
     * 
     * <pre>
     * StringUtils.trimToNull(null)          = null
     * StringUtils.trimToNull("")            = null
     * StringUtils.trimToNull("     ")       = null
     * StringUtils.trimToNull("abc")         = "abc"
     * StringUtils.trimToNull("    abc    ") = "abc"
     * </pre>
     *  
     * @param str  the String to be trimmed, may be null
     * @return the trimmed String, 
     *  <code>null</code> if only chars &lt;= 32, empty or null String input
     * @since 2.0
     */
    public static String trimToNull(String str) {
        String ts = trim(str);
        return (ts == null || ts.length() == 0 ? null : ts);
    }

    /** 
     * <p>Removes control characters (char &lt;= 32) from both 
     * ends of this String returning an empty String ("") if the String
     * is empty ("") after the trim or if it is <code>null</code>.
     * 
     * <p>The String is trimmed using {@link String#trim()}.
     * Trim removes start and end characters &lt;= 32.
     * To strip whitespace use {@link #stripToEmpty(String)}.</p>
     * 
     * <pre>
     * StringUtils.trimToEmpty(null)          = ""
     * StringUtils.trimToEmpty("")            = ""
     * StringUtils.trimToEmpty("     ")       = ""
     * StringUtils.trimToEmpty("abc")         = "abc"
     * StringUtils.trimToEmpty("    abc    ") = "abc"
     * </pre>
     *  
     * @param str  the String to be trimmed, may be null
     * @return the trimmed String, or an empty String if <code>null</code> input
     * @since 2.0
     */
    public static String trimToEmpty(String str) {
        return (str == null ? EMPTY : str.trim());
    }
    
    // Stripping
    //-----------------------------------------------------------------------
    /**
     * <p>Strips whitespace from the start and end of a String.</p>
     * 
     * <p>This is similar to {@link #trim(String)} but removes whitespace.
     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
     * 
     * <p>A <code>null</code> input String returns <code>null</code>.</p>
     * 
     * <pre>
     * StringUtils.strip(null)     = null
     * StringUtils.strip("")       = ""
     * StringUtils.strip("   ")    = ""
     * StringUtils.strip("abc")    = "abc"
     * StringUtils.strip("  abc")  = "abc"
     * StringUtils.strip("abc  ")  = "abc"
     * StringUtils.strip(" abc ")  = "abc"
     * StringUtils.strip(" ab c ") = "ab c"
     * </pre>
     * 
     * @param str  the String to remove whitespace from, may be null
     * @return the stripped String, <code>null</code> if null String input
     */
    public static String strip(String str) {
        return strip(str, null);
    }
    
    /** 
     * <p>Strips whitespace from the start and end of a String  returning
     * <code>null</code> if the String is empty ("") after the strip.</p>
     * 
     * <p>This is similar to {@link #trimToNull(String)} but removes whitespace.
     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
     * 
     * <pre>
     * StringUtils.strip(null)     = null
     * StringUtils.strip("")       = null
     * StringUtils.strip("   ")    = null
     * StringUtils.strip("abc")    = "abc"
     * StringUtils.strip("  abc")  = "abc"
     * StringUtils.strip("abc  ")  = "abc"
     * StringUtils.strip(" abc ")  = "abc"
     * StringUtils.strip(" ab c ") = "ab c"
     * </pre>
     *  
     * @param str  the String to be stripped, may be null
     * @return the stripped String, 
     *  <code>null</code> if whitespace, empty or null String input
     * @since 2.0
     */
    public static String stripToNull(String str) {
        if (str == null) {
            return null;
        }
        str = strip(str, null);
        return (str.length() == 0 ? null : str);
    }

    /** 
     * <p>Strips whitespace from the start and end of a String  returning
     * an empty String if <code>null</code> input.</p>
     * 
     * <p>This is similar to {@link #trimToEmpty(String)} but removes whitespace.
     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
     * 
     * <pre>
     * StringUtils.strip(null)     = ""
     * StringUtils.strip("")       = ""
     * StringUtils.strip("   ")    = ""
     * StringUtils.strip("abc")    = "abc"
     * StringUtils.strip("  abc")  = "abc"
     * StringUtils.strip("abc  ")  = "abc"
     * StringUtils.strip(" abc ")  = "abc"
     * StringUtils.strip(" ab c ") = "ab c"
     * </pre>
     *  
     * @param str  the String to be stripped, may be null
     * @return the trimmed String, or an empty String if <code>null</code> input
     * @since 2.0
     */
    public static String stripToEmpty(String str) {
        return (str == null ? EMPTY : strip(str, null));
    }
    
    /**
     * <p>Strips any of a set of characters from the start and end of a String.
     * This is similar to {@link String#trim()} but allows the characters
     * to be stripped to be controlled.</p>
     *
     * <p>A <code>null</code> input String returns <code>null</code>.
     * An empty string ("") input returns the empty string.</p>
     * 
     * <p>If the stripChars String is <code>null</code>, whitespace is
     * stripped as defined by {@link Character#isWhitespace(char)}.
     * Alternatively use {@link #strip(String)}.</p>
     * 
     * <pre>
     * StringUtils.strip(null, *)          = null
     * StringUtils.strip("", *)            = ""
     * StringUtils.strip("abc", null)      = "abc"
     * StringUtils.strip("  abc", null)    = "abc"
     * StringUtils.strip("abc  ", null)    = "abc"
     * StringUtils.strip(" abc ", null)    = "abc"
     * StringUtils.strip("  abcyx", "xyz") = "  abc"
     * </pre>
     * 
     * @param str  the String to remove characters from, may be null
     * @param stripChars  the characters to remove, null treated as whitespace
     * @return the stripped String, <code>null</code> if null String input
     */
    public static String strip(String str, String stripChars) {
        if (str == null || str.length() == 0) {
            return str;
        }
        str = stripStart(str, stripChars);
        return stripEnd(str, stripChars);
    }

    /**
     * <p>Strips any of a set of characters from the start of a String.</p>
     *
     * <p>A <code>null</code> input String returns <code>null</code>.
     * An empty string ("") input returns the empty string.</p>
     * 
     * <p>If the stripChars String is <code>null</code>, whitespace is
     * stripped as defined by {@link Character#isWhitespace(char)}.</p>
     * 
     * <pre>
     * StringUtils.stripStart(null, *)          = null
     * StringUtils.stripStart("", *)            = ""
     * StringUtils.stripStart("abc", "")        = "abc"
     * StringUtils.stripStart("abc", null)      = "abc"
     * StringUtils.stripStart("  abc", null)    = "abc"
     * StringUtils.stripStart("abc  ", null)    = "abc  "
     * StringUtils.stripStart(" abc ", null)    = "abc "
     * StringUtils.stripStart("yxabc  ", "xyz") = "abc  "
     * </pre>
     * 
     * @param str  the String to remove characters from, may be null
     * @param stripChars  the characters to remove, null treated as whitespace
     * @return the stripped String, <code>null</code> if null String input
     */
    public static String stripStart(String str, String stripChars) {
        int strLen;
        if (str == null || (strLen = str.length()) == 0) {
            return str;
        }
        int start = 0;
        if (stripChars == null) {
            while ((start != strLen) && Character.isWhitespace(str.charAt(start))) {
                start++;
            }
        } else if (stripChars.length() == 0) {
            return str;
        } else {
            while ((start != strLen) && (stripChars.indexOf(str.charAt(start)) != -1)) {
                start++;
            }
        }
        return str.substring(start);
    }

    /**
     * <p>Strips any of a set of characters from the end of a String.</p>
     *
     * <p>A <code>null</code> input String returns <code>null</code>.
     * An empty string ("") input returns the empty string.</p>
     * 
     * <p>If the stripChars String is <code>null</code>, whitespace is
     * stripped as defined by {@link Character#isWhitespace(char)}.</p>
     * 
     * <pre>
     * StringUtils.stripEnd(null, *)          = null
     * StringUtils.stripEnd("", *)            = ""
     * StringUtils.stripEnd("abc", "")        = "abc"
     * StringUtils.stripEnd("abc", null)      = "abc"
     * StringUtils.stripEnd("  abc", null)    = "  abc"
     * StringUtils.stripEnd("abc  ", null)    = "abc"
     * StringUtils.stripEnd(" abc ", null)    = " abc"
     * StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
     * </pre>
     * 
     * @param str  the String to remove characters from, may be null
     * @param stripChars  the characters to remove, null treated as whitespace
     * @return the stripped String, <code>null</code> if null String input
     */
    public static String stripEnd(String str, String stripChars) {
        int end;
        if (str == null || (end = str.length()) == 0) {
            return str;
        }
 
        if (stripChars == null) {
            while ((end != 0) && Character.isWhitespace(str.charAt(end - 1))) {
                end--;
            }
        } else if (stripChars.length() == 0) {
            return str;
        } else {
            while ((end != 0) && (stripChars.indexOf(str.charAt(end - 1)) != -1)) {
                end--;
            }
        }
        return str.substring(0, end);
    }

    // StripAll
    //-----------------------------------------------------------------------
    /**
     * <p>Strips whitespace from the start and end of every String in an array.
     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
     *
     * <p>A new array is returned each time, except for length zero.
     * A <code>null</code> array will return <code>null</code>.
     * An empty array will return itself.
     * A <code>null</code> array entry will be ignored.</p>
     * 
     * <pre>
     * StringUtils.stripAll(null)             = null
     * StringUtils.stripAll([])               = []
     * StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
     * StringUtils.stripAll(["abc  ", null])  = ["abc", null]
     * </pre>
     * 
     * @param strs  the array to remove whitespace from, may be null
     * @return the stripped Strings, <code>null</code> if null array input
     */
    public static String[] stripAll(String[] strs) {
        return stripAll(strs, null);
    }
 
    /**
     * <p>Strips any of a set of characters from the start and end of every
     * String in an array.</p>
     * Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
     *
     * <p>A new array is returned each time, except for length zero.
     * A <code>null</code> array will return <code>null</code>.
     * An empty array will return itself.
     * A <code>null</code> array entry will be ignored.
     * A <code>null</code> stripChars will strip whitespace as defined by
     * {@link Character#isWhitespace(char)}.</p>
     * 
     * <pre>
     * StringUtils.stripAll(null, *)                = null
     * StringUtils.stripAll([], *)                  = []
     * StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
     * StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
     * StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
     * StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]
     * </pre>
     * 
     * @param strs  the array to remove characters from, may be null
     * @param stripChars  the characters to remove, null treated as whitespace
     * @return the stripped Strings, <code>null</code> if null array input
     */
    public static String[] stripAll(String[] strs, String stripChars) {
        int strsLen;