public class Main {

    public static void main(String[] args) {

        double number = 123456789.123456789;
        double number2 = 123.123456789;
        double number3 = 123.456;

        printNumber(number);
        printNumber(number2);
        printNumber(number3);
    }

    private static void printNumber(double number) {
        String formattedNumber = String.format("%.15f", number);
        System.out.printf("%.15s", formattedNumber);
        System.out.println();
    }
}