private void convert() {
        check();
        
        String text = numberField.getText();

        String lang = this.langComboBox.getSelectedItem().toString();
        String type = this.digitTypeComboBox.getSelectedItem().toString();
        String result = "";
        if (lang.equalsIgnoreCase("english")) {
            if (type.equalsIgnoreCase("Amount")) {
                BigDecimal bd = new BigDecimal(text);
                result = Numerals.amount(bd);
            } else if (type.equalsIgnoreCase("Integer")) {
                BigInteger bd = new BigInteger(text);
                result = Numerals.english(bd);
            } else {
                System.err.println("unsupported type:" + type);
            }
        } else if (lang.equalsIgnoreCase("russian")) {
            if (type.equalsIgnoreCase("Amount")) {
                BigDecimal bd = new BigDecimal(text);
                result = Numerals.russianRubles(bd);
            } else if (type.equalsIgnoreCase("Integer")) {
                BigInteger bd = new BigInteger(text);
                result = Numerals.russian(bd);
            } else {
                System.err.println("unsupported type:" + type);
            }
        } else {
            System.err.println("unsupported language:" + lang);
        }

        this.wordNumber.setText(result);
    }