National Letter Selector Doesn't Appear

What I had to do was to implement a text input able to color letters green or red. My piece of code can do this but there is a problem. I can't write an national letter because the

Solution 1:

The InputFilter helped me resolve the problem:

InputFilter filter = new InputFilter() {
        final String good_letter = "<font color='#2FEE0D'>$</font>";
        final String bad_letter = "<font color='#FF0000'>$</font>";

        public CharSequence filter(CharSequence source, int start, int end, 
                Spanned dest, int dstart, int dend) 
        {
            String input = dest.toString().substring(0, dstart) + source.
                    subSequence(start, end) + dest.toString().substring(dend);
            StringBuffer output = new StringBuffer();
            List<Entry<Character, Boolean>> correction = Learn.this.
                learn_manager.getLetters(input);

            Log.d(TAG, "afterTextChanged: input size (" + input.length() + 
                    ")");

            System.out.println(input);

            for (int i = dstart; i < dstart + end; i++)
            {                    
                if (correction.get(i).getValue())
                {
                    output.append(this.good_letter.replace('$', correction.
                            get(i).getKey()));
                } else {

                    output.append(this.bad_letter.replace('$', correction.
                            get(i).getKey()));
                }
            }

            return Html.fromHtml(output.toString());
        } 
};