Java String align right with filling character

//package com.demo2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        CharSequence cs = "demo2s.com";
        int width = 30;
        char c = '.';
        System.out.println(alignRight(cs, width, c));
    }// ww  w.  ja v  a  2s .  c om

    public static String alignRight(CharSequence cs, int width, char c) {
        if (cs == null)
            return null;
        int len = cs.length();
        if (len >= width)
            return cs.toString();
        return dup(c, width - len) + cs;
    }

    public static String dup(CharSequence cs, int num) {
        if ((isEmpty(cs)) || (num <= 0))
            return "";
        StringBuilder sb = new StringBuilder(cs.length() * num);
        for (int i = 0; i < num; ++i)
            sb.append(cs);
        return sb.toString();
    }

    public static String dup(char c, int num) {
        if ((c == 0) || (num < 1))
            return "";
        StringBuilder sb = new StringBuilder(num);
        for (int i = 0; i < num; ++i)
            sb.append(c);
        return sb.toString();
    }

    public static boolean isEmpty(CharSequence cs) {
        return ((cs == null) || (cs.length() == 0));
    }
}