Android. Inputfilter not working properly

Question

I am using filter for my edit text. I need to enter values ​​with two digits after the dot. But if you enter a number then a point and delete the number before the point, the point does not clear, I need the point to be deleted. Here is my filter method:

 @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {    
        String destStr = dest.toString();
        String sourceStr = source.toString();
        String stringToMatch = destStr.substring(0,dstart) + source.toString() + destStr.substring(dend);
        stringToMatch = stringToMatch.replace(String.valueOf((char) 160), "");
        Matcher matcher = mPattern.matcher(stringToMatch);
        if (!matcher.matches()) {
            return "";
        }
        return sourceStr.replace(',', '.');
    }

And this is my regex

"([1-9][0-9]*)(([.,,][0-9]{1,2})|([.,,])?)"

When the filter returns "" in my edit text the value is not set to "". Please, help me.