I believe your code is okay. It appears that your problem is that you need to do a specific character conversion, and maybe your "real" input is not being encoded correctly. To test, I would do a standard step by step CharSet encoding/decoding, to see where things are breaking.
Your encodings look fine, http://docs.oracle.com/javase/1.6/docs/guide/intl/encoding.doc.html
And the following seems to run normally :
//i suspect your problem is here - make sure your encoding the string correctly from the byte/char stream. That is, make sure that you want "iso-8859-1" as your input characters.
Charset charsetE = Charset.forName("iso-8859-1");
CharsetEncoder encoder = charsetE.newEncoder();
//i believe from here to the end will probably stay the same, as per your posted example.
Charset charsetD = Charset.forName("UTF-8");
CharsetDecoder decoder = charsetD.newDecoder();
ByteBuffer bbuf = encoder.encode(CharBuffer.wrap(inputString));
CharBuffer cbuf = decoder.decode(bbuf);
final String result = cbuf.toString();
System.out.println(result);