filter.java

InputFilter[] filters = new InputFilter[1];
                filters[0] = new InputFilter() {
                    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
                        if (end > start) {
                            String destTxt = dest.toString();
                            String resultingTxt = destTxt.substring(0, dstart) + source.subSequence(start, end) + destTxt.substring(dend);
                            if (!resultingTxt.matches("^\\d{1,3}(\\.(\\d{1,3}(\\.(\\d{1,3}(\\.(\\d{1,3})?)?)?)?)?)?")) {
                                return "";
                            } else {
                                String[] splits = resultingTxt.split("\\.");
                                for (int i = 0; i < splits.length; i++) {
                                    if (Integer.valueOf(splits[i]) > 255) {
                                        return "";
                                    }
                                }
                            }
                        }
                        return null;
                    }
                };
                et_setting_ip.setFilters(filters);