@Override
	protected Object doInBackground() throws Exception {
		addPropertyChangeListener(this);
		try{
		if (op.equals(Operation.LOAD))aDoc.load(fis, append, this);
		if (op.equals(Operation.SAVE))aDoc.save(fos, this);
		} catch (Exception e){
			pw.close();
			this.exception = e;
			e.printStackTrace();
		}
		
		
		return null;
	}