Mask utility

MaskBuilder.java

import android.text.Editable;
import android.text.Selection;
import android.text.TextWatcher;
import android.widget.TextView;

public abstract class MaskBuilder {

    public static final String CREDIT_CARD_MASK = "####.####.####.####";
    public static final String DATE_MASK = "##/##/####";
    public static final String CPF_MASK = "###.###.###-##";
    public static final String CNPJ_MASK = "##.###.###/####-##";
    public static final String ZIP_CODE_MASK = "#####-###";

    private MaskBuilder() {
        throw new UnsupportedOperationException();
    }

    public static TextWatcher build(final String mask, final TextView textView) {
        return new TextWatcher() {
            boolean isUpdating;
            String old = "";

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                isUpdating = (after == 0);
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                textView.removeTextChangedListener(this);
                int selectionOffset = s.length() - count - start;

                String result;
                if (!isUpdating) {
                    result = mask(s.toString());
                } else {
                    result = s.toString();
                }

                textView.setText(result);

                if (selectionOffset >= 0) {
                    setSelection(textView, result.length() - selectionOffset);
                } else {
                    setSelection(textView, result.length());
                }

                textView.addTextChangedListener(this);
            }

            @Override
            public void afterTextChanged(Editable s) {
            }

            private String mask(CharSequence s) {
                String str = s.toString().replaceAll("[^\\d]", "");
                String maskedText = "";

                int i = 0;
                for (char m : mask.toCharArray()) {
                    if (m != '#' && str.length() > old.length()) {
                        maskedText += m;
                        continue;
                    }
                    try {
                        maskedText += str.charAt(i);
                    } catch (Exception e) {
                        break;
                    }

                    i++;
                }
                return maskedText;
            }
        };

    }

    private static void setSelection(TextView textView, int index) {
        Selection.setSelection((Editable) textView.getText(), index);
    }
    
}