Java Utililty Methods String Unescape

StringBuilder buf = new StringBuilder();
int i = quoted.length();
for (int n = 0; n < i; n++) {
    char c = quoted.charAt(n);
    if (c != '\\')
        buf.append(c);
    else if (n < i - 1 && quoted.charAt(n + 1) == '\\') {
        buf.append(c);
...

if (s == null)
    return null;
if (s.equals(""))
    return null;
StringBuilder result = new StringBuilder(s.length());
for (int i = 0; i < s.length(); i++) {
    if (s.charAt(i) == '\\') {
        if (i + 1 == s.length())
...

if (s == null || s.length() == 0) {
    return s;
StringBuffer sb = new StringBuffer(s.length());
for (int i = 0; i < s.length(); ++i) {
    char c = s.charAt(i);
    switch (c) {
    case '%':
...

String value = s;
value = value.replaceAll("&lt;", "<");
value = value.replaceAll("&gt;", ">");
value = value.replaceAll("&amp;", "&");
value = value.replaceAll("&quot;", "\"");
value = value.replaceAll("&apos;", "'");
return value;

StringBuffer sbuf = new StringBuffer();
int i = 0;
int len = s.length();
while (i < len) {
    int ch = s.charAt(i);
    if (ch == '+') { 
        sbuf.append(' ');
    } else if ('A' <= ch && ch <= 'Z') { 
...

if (s == null || s.length() == 0)
    return s;
StringBuilder sb = new StringBuilder();
char prev_ch = 0;
for (int i = 0, len = s.length(); i < len; i++) {
    char ch = s.charAt(i);
    switch (ch) {
    case '\\':
...

int l = s.length();
StringBuffer dest = null;
int i = 0;
while (i < l - 1) {
    char c = s.charAt(i);
    if (c == '\\') {
        if (dest == null) {
            dest = new StringBuffer(l);
...

if (s.startsWith(QUOTE) && s.endsWith(QUOTE)) {
    s = s.substring(1, s.length() - 2);
    if (s.contains(ESCAPED_QUOTE))
        s = s.replace(ESCAPED_QUOTE, QUOTE);
return s;

return unescape(s, null);

if (s == null) {
    throw new IllegalArgumentException("The String to unescape may not be null.");
StringBuilder sb = new StringBuilder();
boolean escaped = false;
for (int i = 0; i < s.length(); i++) {
    char c = s.charAt(i);
    if (escaped) {
...