Hello I am looking for a way to detect if a string has being encoded
For example
String name = \"Hellä world\";
String encoded = new String(n
Sounds like you want to check if a string that was decoded from bytes in latin1 could have been decoded in UTF-8, too. That's easy because illegal byte sequences are replaced by the character \ufffd:
String recoded = new String(encoded.getBytes("iso-8859-1"), "UTF-8");
return recoded.indexOf('\uFFFD') == -1; // No replacement character found