private final void saveProps() {
		if (props == null) {
			props = new Properties();
		}

		// remove whitespaces
		tf_credID.setText(tf_credID.getText().replaceAll("\\s", ""));
		tf_credIBAN.setText(tf_credIBAN.getText().replaceAll("\\s", ""));
		tf_credBIC.setText(tf_credBIC.getText().replaceAll("\\s", ""));
		tf_execDate.setText(tf_execDate.getText().replaceAll("\\s", ""));

		try {
			// trim execDate
			tf_execDate.setText(tf_execDate.getText().substring(0, 10));

			// set all props
			props.put(StaticString.P_CRED_NAME, tf_credName.getText());
			props.put(StaticString.P_CRED_ID, tf_credID.getText());
			props.put(StaticString.P_CRED_IBAN, tf_credIBAN.getText());
			props.put(StaticString.P_CRED_BIC, tf_credBIC.getText());
			props.put(StaticString.P_EXEC_DATE, tf_execDate.getText());
			if (cb_excelSheetName != null) {
				props.put(StaticString.P_EXCEL_SHEET, cb_excelSheetName
						.getSelectedItem().toString());
			}
			// save properties to project root folder
			props.store(new FileOutputStream(StaticString.PROPS_NAME), null);

		} catch (Exception e1) {
			e1.printStackTrace();
		}
	}