實現簡單的二進制

public static void number(int d) {
        int a = d;
        List<String> list = new ArrayList<>();
        boolean s = true;
        while (s) {
            list.add(a % 2 + "");
            a = a / 2;
            if (a == 0) {
                s = false;
            }
        }
        for (int i = list.size() - 1; i >= 0; i--) {
            System.out.print(list.get(i));
        }
    }