Conversion ISO-8859-7- UTF-8 and UTF-8 - ISO-8859-7

Question

Hi, I written this function to do a Charset conversion
from ISO-8859-7 to UTF-8 and vice versa
void ChangeChersetEncoding(String EncodingType)
String GrammarText;
try
GrammarText = Editor.getText();
b = GrammarText.getBytes(LastEncoding);
String strTemp = new String(b,EncodingType);
Editor.setText(strTemp);
LastEncoding = EncodingType;
catch (UnsupportedEncodingException e)
JOptionPane.showMessageDialog(this, "Error: " + e.getMessage
() , "Error", JOptionPane.ERROR_MESSAGE);
The steps followed are:
1)I initialize Editor (that is a JEditorPane) with a InputStreamReader, that use by default "CP1252"(window - latin1) charset encoding.
2)When I call the function the first time with EncodingType = "ISO-8859-7" and LastEncoding = "CP1252"(window - latin1), Editor shows greek character as I aspected.
3)When I call the function the second time with EncodingType = "UTF-8" and LastEncoding = "ISO-8859-7", Editor shows unknown character ('�') as I aspected.
4)The problem is when I call the function the third time with EncodingType = "ISO-8859-7" and LastEncoding = "UTF-8" Editor don't show the original greek text, as I didn't aspect.
Thank you for all.

Answer 1

b = GrammarText.getBytes(LastEncoding);
String strTemp = new String(b,EncodingType);Here you take a String (which is in Unicode) and convert it to bytes, using "LastEncoding". Next you take those bytes and convert them back to a String, assuming that they were encoded using "EncodingType". But they weren't, so at best this will do nothing and at worst it will produce garbage. It certainly won't do anything useful.
As I said all Java strings are in Unicode. If you want to convert something from one encoding to another encoding, you can only convert an array of bytes to a String using the first encoding, then convert that back to bytes using the second encoding. Converting a String to a String just makes no sense.