charsetutils.java

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     * and returns the number of characters present in the specified string.</p>
     *
     * <p>An example would be:</p>
     * <ul>
     *  <li>count(&quot;hello&quot;, {&quot;c-f&quot;, &quot;o&quot;}) returns 2.</li>
     * </ul>
     *
     * @see #evaluateSet(java.lang.String[]) for set-syntax.
     * @param str  String to count characters in, may be null
     * @param set  String[] set of characters to count, may be null
     * @return character count, zero if null string input
     */
    public static int count(String str, String[] set) {
        if (str == null || str.length() == 0 || set == null || set.length == 0) {
            return 0;
        }
        CharSet chars = evaluateSet(set);
        int count = 0;
        char[] chrs = str.toCharArray();
        int sz = chrs.length;
        for(int i=0; i<sz; i++) {
            if(chars.contains(chrs[i])) {
                count++;
            }
        }
        return count;
    }

    // Keep
    //-----------------------------------------------------------------------
    /**
     * <p>Takes an argument in set-syntax, see evaluateSet,
     * and keeps any of characters present in the specified string.</p>
     *
     * <pre>
     * CharSetUtils.keep(null, *)        = null
     * CharSetUtils.keep("", *)          = ""
     * CharSetUtils.keep(*, null)        = ""
     * CharSetUtils.keep(*, "")          = ""
     * CharSetUtils.keep("hello", "hl") = "hll"
     * CharSetUtils.keep("hello", "le") = "ell"
     * </pre>
     *
     * @see #evaluateSet(java.lang.String[]) for set-syntax.
     * @param str  String to keep characters from, may be null
     * @param set  String set of characters to keep, may be null
     * @return modified String, <code>null</code> if null string input
     * @since 2.0
     */
    public static String keep(String str, String set) {
        if (str == null) {
            return null;
        }
        if (str.length() == 0 || set == null || set.length() == 0) {
            return "";
        }
        String[] strs = new String[1];
        strs[0] = set;
        return keep(str, strs);
    }
    
    /**
     * <p>Takes an argument in set-syntax, see evaluateSet,
     * and keeps any of characters present in the specified string.</p>
     *
     * <p>An example would be:</p>
     * <ul>
     *  <li>keep(&quot;hello&quot;, {&quot;c-f&quot;, &quot;o&quot;})
     *   returns &quot;hll&quot;</li>
     * </ul>
     *
     * @see #evaluateSet(java.lang.String[]) for set-syntax.
     * @param str  String to keep characters from, may be null
     * @param set  String[] set of characters to keep, may be null
     * @return modified String, <code>null</code> if null string input
     * @since 2.0
     */
    public static String keep(String str, String[] set) {
        if (str == null) {
            return null;
        }
        if (str.length() == 0 || set == null || set.length == 0) {
            return "";
        }
        return modify(str, set, true);
    }

    // Delete
    //-----------------------------------------------------------------------
    /**
     * <p>Takes an argument in set-syntax, see evaluateSet,
     * and deletes any of characters present in the specified string.</p>
     *
     * <pre>
     * CharSetUtils.delete(null, *)        = null
     * CharSetUtils.delete("", *)          = ""
     * CharSetUtils.delete(*, null)        = *
     * CharSetUtils.delete(*, "")          = *
     * CharSetUtils.delete("hello", "hl") = "hll"
     * CharSetUtils.delete("hello", "le") = "ell"
     * </pre>
     *
     * @see #evaluateSet(java.lang.String[]) for set-syntax.
     * @param str  String to delete characters from, may be null
     * @param set  String set of characters to delete, may be null
     * @return modified String, <code>null</code> if null string input
     */
    public static String delete(String str, String set) {
        if (str == null || str.length() == 0 || set == null || set.length() == 0) {
            return str;
        }
        String[] strs = new String[1];
        strs[0] = set;
        return delete(str, strs);
    }
    
    /**
     * <p>Takes an argument in set-syntax, see evaluateSet,
     * and deletes any of characters present in the specified string.</p>
     *
     * <p>An example would be:</p>
     * <ul>
     *  <li>delete(&quot;hello&quot;, {&quot;c-f&quot;, &quot;o&quot;}) returns
     *   &quot;hll&quot;</li>
     * </ul>
     *
     * @see #evaluateSet(java.lang.String[]) for set-syntax.
     * @param str  String to delete characters from, may be null
     * @param set  String[] set of characters to delete, may be null
     * @return modified String, <code>null</code> if null string input
     */
    public static String delete(String str, String[] set) {
        if (str == null || str.length() == 0 || set == null || set.length == 0) {
            return str;
        }
        return modify(str, set, false);
    }

    //-----------------------------------------------------------------------
    // Implementation of delete and keep
    private static String modify(String str, String[] set, boolean expect) {
        CharSet chars = evaluateSet(set);
        StringBuffer buffer = new StringBuffer(str.length());
        char[] chrs = str.toCharArray();
        int sz = chrs.length;
        for(int i=0; i<sz; i++) {
            if(chars.contains(chrs[i]) == expect) {
                buffer.append(chrs[i]);
            }
        }
        return buffer.toString();
    }

    // Translate
    //-----------------------------------------------------------------------
    /**
     * <p>Translate characters in a String.
     * This is a multi character search and replace routine.</p>
     *
     * <p>An example is:</p>
     * <ul>
     *   <li>translate(&quot;hello&quot;, &quot;ho&quot;, &quot;jy&quot;)
     *    => jelly</li>
     * </ul>
     *
     * <p>If the length of characters to search for is greater than the
     * length of characters to replace, then the last character is 
     * used.</p>
     * 
     * <pre>
     * CharSetUtils.translate(null, *, *) = null
     * CharSetUtils.translate("", *, *) = ""
     * </pre>
     *
     * @param str  String to replace characters in, may be null
     * @param searchChars   a set of characters to search for, must not be null
     * @param replaceChars  a set of characters to replace, must not be null or empty ("")
     * @return translated String, <code>null</code> if null string input
     * @throws NullPointerException if <code>with</code> or <code>repl</code> 
     *  is <code>null</code>
     * @throws ArrayIndexOutOfBoundsException if <code>with</code> is empty ("")
     * @deprecated Use {@link StringUtils#replaceChars(String, String, String)}.
     *             Method will be removed in Commons Lang 3.0.
     */
    public static String translate(String str, String searchChars, String replaceChars) {
        if (str == null || str.length() == 0) {
            return str;
        }
        StringBuffer buffer = new StringBuffer(str.length());
        char[] chrs = str.toCharArray();
        char[] withChrs = replaceChars.toCharArray();
        int sz = chrs.length;
        int withMax = replaceChars.length() - 1;
        for(int i=0; i<sz; i++) {
            int idx = searchChars.indexOf(chrs[i]);
            if(idx != -1) {
                if(idx > withMax) {
                    idx = withMax;
                }
                buffer.append(withChrs[idx]);
            } else {
                buffer.append(chrs[i]);
            }
        }
        return buffer.toString();
    }

}