Java: Base64 Encode

I used this function to encode a string using base64 encoding for my java card applet.

public static String base64Encode(String s) {
    String table="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
            + "abcdefghijklmnopqrstuvwxyz0123456789+/";
    String b="";
    String r="";
    int pad;
       
    for (int c : s.toCharArray()) {
        b+=rjust(Integer.toBinaryString(c), 8, "0");
    }
           
    for (int i=0; i<b.length(); i+=6) {
        r+=table.charAt(Integer.parseInt(ljust(b.substring(i, i+6), 6, "0"), 2));
        pad=6-b.substring(i, i+6).length();
        switch (pad) {
            case 0: r+=""; break;
            case 4: r+="=="; break;
            case 2: r+="="; break; }                  
    }
    return r;
}

Both rjust and ljust that you can find in the function above are custom functions similar to python's rjust and ljust.