static byte[] encode(String charsetName, char[] ca, int off, int len) throws UnsupportedEncodingException {
StringEncoder se = deref(encoder);
String csn = (charsetName == null) ? "ISO-8859-1" : charsetName;
if ((se == null) || !(csn.equals(se.requestedCharsetName())
|| csn.equals(se.charsetName()))) {
se = null;
try {
Charset cs = lookupCharset(csn);
if (cs != null)
se = new StringEncoder(cs, csn);
} catch (IllegalCharsetNameException x) {}
if (se == null)
throw new UnsupportedEncodingException (csn);
set(encoder, se);
}
return se.encode(ca, off, len);
}