inifiles with serialize ??

Hello,
I need to store some variables on harddisk in order to restore their
values in successive sessions.

I took this simple aproach:

Inifile as map, loaded at the startup.
 - - - - - - - - - - - - - - - - - - - -
Map<String, String> ini=new HashMap<String,String>();
try {
  ObjectInputStream input=new ObjectInputStream(new
FileInputStream(inifile));
  ini=(HashMap<String,String>)input.readObject();
} catch (IOException e) {}
catch (ClassNotFoundException e) {}
 - - - - - - - - - - - - - - - - - - - -

Changes during the session
ini.put("key","value");

Storing at closing app:
 - - - - - - - - - - - - - - - - - - - -
public void windowClosing(WindowEvent e) {
try {
ObjectOutputStream output=new ObjectOutputStream(
  new FileOutputStream(inifile));
output.writeObject(ini);
} catch (IOException ex) {}
 - - - - - - - - - - - - - - - - - - - -

My question is:
How realible is this approach with respect to future changes of Java?
The byte-representation of Map might change ?

Juergen