/**
     * do some operations with strings
     */
    void testStrings() {
        String text = "Shop is not very good place.";
        System.out.println(text.substring(3));
        System.out.println(text.indexOf('.'));
        System.out.println(text.charAt(15));
    }

    /**
     * visualise some functions with locale and format
     */
    void testFormatAndLocale() {
        double price = 56655.34;
        System.out.printf("this price is %f \n", price);
        String francePrice = NumberFormat.getCurrencyInstance(Locale.FRANCE).format(price);
        String chinaPrice = NumberFormat.getCurrencyInstance(Locale.CHINA).format(price);
        System.out.println(francePrice + '\n' + chinaPrice);
    }