public class Demo {
    public static void main(String[] args) {
        String USADate = "4/23/2011";
        String [] numbers = USADate.split("/");
        String temp = null;
        temp = numbers[0];
        numbers[0] = numbers[1] + ".";
        numbers[1] = "0" + temp + ".";
        System.out.println(numbers[0] + numbers[1] + numbers[2]);
    }
}