Custom format edit text input android to accept credit card number

Question

how to make edit text accept input in format

4digitnumber-4dignumber-4dignumber-4dignumber   

The code

text.addTextChangedL         


        

Answer 1

This is working:

public class EditTextSample extends Activity {
    // This regexp has to be improved, it does not detect case where you have
    // more than 4 digits in a middle group like: 1234-12345-123
    static final Pattern CODE_PATTERN = Pattern.compile("([0-9]{0,4})|([0-9]{4}-)+|([0-9]{4}-[0-9]{0,4})+");

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.edit_text_sample);

        final EditText editText = (EditText) findViewById(R.id.input);
        editText.addTextChangedListener(new TextWatcher() {

            @Override
            public void afterTextChanged(Editable s) {
                Log.w("", "input" + s.toString());

                if (s.length() > 0 && !CODE_PATTERN.matcher(s).matches()) {
                    String input = s.toString();
                    String numbersOnly = keepNumbersOnly(input);
                    String code = formatNumbersAsCode(numbersOnly);

                    Log.w("", "numbersOnly" + numbersOnly);
                    Log.w("", "code" + code);

                    editText.removeTextChangedListener(this);
                    editText.setText(code);
                    // You could also remember the previous position of the cursor
                    editText.setSelection(code.length());
                    editText.addTextChangedListener(this);
                }
            }

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

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
            }

            private String keepNumbersOnly(CharSequence s) {
                return s.toString().replaceAll("[^0-9]", ""); // Should of course be more robust
            }

            private String formatNumbersAsCode(CharSequence s) {
                int groupDigits = 0;
                String tmp = "";
                for (int i = 0; i < s.length(); ++i) {
                    tmp += s.charAt(i);
                    ++groupDigits;
                    if (groupDigits == 4) {
                        tmp += "-";
                        groupDigits = 0;
                    }
                }
                return tmp;
            }
        });
    }
}