Java Utililty Methods String Escape

if (str == null) {
    return null;
final StringBuffer buf = new StringBuffer();
final int len = str.length();
for (int i = 0; i < len; i++) {
    final char c = str.charAt(i);
    if (Arrays.binarySearch(REGEXP_CHARS, c) >= 0) {
...

char[] specialSymbol = new char[] { '$', '(', ')', '*', '+', '.', '[', '?', '^', '{', '|', '}', '\\' };
List<Character> specialList = new ArrayList<Character>();
for (int i = 0; i < specialSymbol.length; i++) {
    specialList.add(Character.valueOf(specialSymbol[i]));
StringBuffer sb = new StringBuffer(expr);
for (int i = 0; i < sb.length(); i++) {
    int index = specialList.indexOf(Character.valueOf(sb.charAt(i)));
...

return RESERVED_KEYWORDS.contains(input) ? "\"" + input + "\"" : input;

chars = "%" + chars;
for (int i = 0; i < chars.length(); i++) {
    String charAsStr = chars.substring(i, i + 1);
    try {
        str = str.replace(charAsStr, URLEncoder.encode(charAsStr, "UTF-8"));
    } catch (UnsupportedEncodingException e) {
        throw new RuntimeException("UTF-8 encoding not found:", e);
return str;

StringBuilder stringBuilder = new StringBuilder(value);
for (int i = 0; i < stringBuilder.length(); i++) {
    boolean isCharacterToBeEscaped = Arrays.binarySearch(CHARACTERS_TO_BE_ESCAPED_FOR_SOLR,
            stringBuilder.charAt(i)) >= 0;
    if (isCharacterToBeEscaped) {
        stringBuilder.insert(i, '\\');
        i++;
return stringBuilder.toString();

try {
    return java.net.URLEncoder.encode(name, "UTF-8");
} catch (UnsupportedEncodingException e) {
    throw new RuntimeException(e);

if (s == null) {
    return null;
StringBuilder result = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
    char c = s.charAt(i);
    char ca = (Character.isDefined(c)) ? c : UNICODE_REPLACEMENT;
    result.append(ca);
...

StringBuilder returnValue = new StringBuilder("");
for (int i = 0; i < input.length(); i++) {
    char ch = input.charAt(i);
    if (!escapeAscii && ch >= 0x0020 && ch <= 0x007e) {
        returnValue.append(ch);
    } else {
        returnValue.append("\\u");
        String hex = Integer.toHexString(input.charAt(i) & 0xFFFF);
...

if (anyURI == null)
    return null;
if (escapePercent)
    anyURI = anyURI.replaceAll("\\" + PERCENT, (String) fCharToEscaped.get(PERCENT)); 
String key = null;
for (Iterator i = fCharToEscaped.keySet().iterator(); i.hasNext();) {
    key = (String) i.next();
    if (key.equals(PERCENT))
...

s = s.replaceAll(" ", "_");
s = s.replaceAll("\\t", "_");
try {
    s = URLEncoder.encode(s, "UTF8");
    return s;
} catch (UnsupportedEncodingException e) {
    e.printStackTrace();
return "";