Android widget for inputting numeric IP addresses

IPAddressText.java

/**
 * EditText that only allows input of IP Addresses, using the Phone
 * input type, and automatically inserts periods at the earliest appropriate
 * interval.
 */

// Note; this probably isn't the best pattern for this - a Factory of Decorator
// pattern would have made more sense, rather than inheritance. However, this
// pattern is consistent with how other android Widgets are invoked, so I went
// with this to prevent confusion

public class IPAddressText extends EditText {

public IPAddressText(Context context) {
    super(context);

    setInputType(InputType.TYPE_CLASS_PHONE);
    setFilters(new InputFilter[] { new InputFilter() {
        @Override
        public CharSequence filter(CharSequence source, int start, int end, android.text.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;
        }
    }
    });

    addTextChangedListener(new TextWatcher() {
        boolean deleting = false;
        int lastCount = 0;

        @Override
        public void afterTextChanged(Editable s) {
            if (!deleting) {
                String working = s.toString();
                String[] split = working.split("\\.");
                String string = split[split.length - 1];
                if (string.length() == 3 || string.equalsIgnoreCase("0")
                        || (string.length() == 2 && Character.getNumericValue(string.charAt(0)) > 1)) {
                    s.append('.');
                    return;
                }
            } 
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            if (lastCount < count) {
                deleting = false;
            } else {
                deleting = true;
            }
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // Nothing happens here
        }
    });
}