public class Base64{

    public static int getBase64ByteSize(String str){
      String specials = "\u00C4 \u00E4 \u00D6 \u00F6 \u00DC \u00FC \u00DF";

      int amountspecialSigns = countSpecialSigns(str, specials);
      System.out.println(amountspecialSigns);

      int n = str.length() + amountspecialSigns;

      int z = 4 * (int) Math.ceil( (double) n/3);

      return z;
    }

    public static int countSpecialSigns(String str, String specialSigns){
        int count = 0;
        char[] chars = specialSigns.toCharArray();
        for (int i=0; i < str.length(); i++){
          for (int l=0; l< chars.length; l++){
              if (str.charAt(i) == chars[l]){
                   count++;
              }
          }
        }
        return count;
    }

    public static void main(String[] args){

      System.out.println(getBase64ByteSize("Hallo"));
    }
  }