Brazilian Phone Number Formatter

PhoneMask.java

import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;

public class PhoneMask implements TextWatcher {
    private static final String PHONE_MASK = "(##)####-####";
    private final char[] PHONE_MASK_ARRAY = PHONE_MASK.toCharArray();

    private boolean isInTextChanged;
    private boolean isInAfterTextChanged;
    private EditText editText;
    private int shiftCursor;
    private String text;
    private int cursor;

    public PhoneMask(EditText editText) {
        super();
        this.editText = editText;
        isInTextChanged = false;
        isInAfterTextChanged = false;
    }

    @Override
    public synchronized void beforeTextChanged(CharSequence s, int start, int count, int after) {
        shiftCursor = after - count;
    }

    @Override
    public synchronized void onTextChanged(CharSequence s, int start, int before, int count) {
        if (!isInTextChanged) {
            isInTextChanged = true;

            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < s.length(); i++) {
                char symbol = s.charAt(i);
                if (symbol >= '0' && symbol <= '9')
                    sb.append(symbol);
            }
            String digits = sb.toString();

            sb.setLength(0);
            int j = 0;
            for (int i = 0; i < digits.length(); i++) {
                char digit = digits.charAt(i);
                while (j < PHONE_MASK_ARRAY.length) {
                    if (PHONE_MASK_ARRAY[j] == '#') {
                        sb.append(digit);
                        j++;
                        break;
                    } else {
                        sb.append(PHONE_MASK_ARRAY[j]);
                        j++;
                    }
                }
            }

            cursor = editText.getSelectionStart();
            text = sb.toString();

            if (shiftCursor > 0) {
                if (cursor > text.length())
                    cursor = text.length();
                else {
                    while (cursor < PHONE_MASK_ARRAY.length && PHONE_MASK_ARRAY[cursor - 1] != '#') {
                        cursor++;
                    }
                }
            } else if (shiftCursor < 0) {
                while (cursor > 0 && PHONE_MASK_ARRAY[cursor - 1] != '#') {
                    cursor--;
                }
            }
        }
    }

    public synchronized void afterTextChanged(Editable s) {
        if (!isInAfterTextChanged) {
            isInAfterTextChanged = true;

            editText.setText(text);
            editText.setSelection(cursor);

            isInTextChanged = false;
            isInAfterTextChanged = false;
        }
    }
}

Based on this stackoverflow: http://stackoverflow.com/questions/5645332/android-edittext-keyboard-textwatcher-problem