formatting expiry date in mm/yy format

Question

Hi I am writing an edittext in which I want expiry date of the credit card in MM/YY format. The algorithm I want to implement is as follows: If user enters anything from 2 to 9. I change the text input to 02/ to 09/ If the user enters 1, then I wait for the next digit and check if the int value month if less than 12. Here is my code for this.

@Override
            public void afterTextChanged(Editable s) { 
            String input = s.toString();
                if (s.length() == 1) {
                        int month = Integer.parseInt(input);
                        if (month > 1) {
                            mExpiryDate.setText("0" + mExpiryDate.getText().toString() + "/");
                            mExpiryDate.setSelection(mExpiryDate.getText().toString().length());
                            mSeperator = true;
                        }

                }
                else if (s.length() == 2) {
                        int month = Integer.parseInt(input);
                        if (month <= 12) {
                            mExpiryDate.setText(mExpiryDate.getText().toString() + "/");
                            mExpiryDate.setSelection(mExpiryDate.getText().toString().length());                            
                            mSeperator = true;
                        }
                }
                else {

                }

            }

This works fine until I press a softkey back button. The back slash never goes back. The reason is the second if condition is always met. I am confused about how to solve this. How do I handle the back button inside aftertextchanged? Please help.

Answer 1

See my comment above to understand your issue. You might use this to verify the user input with your textwatcher:

SimpleDateFormat formatter = 
    new SimpleDateFormat("MM/yy", Locale.GERMANY);
Calendar expiryDateDate = Calendar.getInstance();
try {
    expiryDateDate.setTime(formatter.parse(mExpiryDate.getText().toString()));
} catch (ParseException e) {
    //not valid
}
// expiryDateDate has a valid date from the user

So in complete it would be:

String lastInput ="";

@Override
public void afterTextChanged(Editable s) { 
     String input = s.toString();
     SimpleDateFormat formatter = new SimpleDateFormat("MM/yy", Locale.GERMANY);
    Calendar expiryDateDate = Calendar.getInstance();
    try {
        expiryDateDate.setTime(formatter.parse(input));
    } catch (ParseException e) {
        if (s.length() == 2 && !lastInput.endsWith("/")) {
            int month = Integer.parseInt(input);
            if (month <= 12) {
               mExpiryDate.setText(mExpiryDate.getText().toString() + "/");
            }
        }else if (s.length() == 2 && lastInput.endsWith("/")) {
            int month = Integer.parseInt(input);
            if (month <= 12) {
               mExpiryDate.setText(mExpiryDate.getText().toString().subStr(0,1);
            }
        }
        lastInput = mExpiryDate.getText().toString();
        //because not valid so code exits here
        return;
    }
    // expiryDateDate has a valid date from the user
    // Do something with expiryDateDate here
}

Finally the complete solution:

String input = s.toString();
SimpleDateFormat formatter = new SimpleDateFormat("MM/yy", Locale.GERMANY);
Calendar expiryDateDate = Calendar.getInstance();
try {
   expiryDateDate.setTime(formatter.parse(input));
} catch (ParseException e) {

} catch (java.text.ParseException e) {
if (s.length() == 2 && !mLastInput.endsWith("/")) {
   int month = Integer.parseInt(input);
   if (month <= 12) {
      mExpiryDate.setText(mExpiryDate.getText().toString() + "/");
      mExpiryDate.setSelection(mExpiryDate.getText().toString().length());
   }
}else if (s.length() == 2 && mLastInput.endsWith("/")) {
   int month = Integer.parseInt(input);
    if (month <= 12) {
       mExpiryDate.setText(mExpiryDate.getText().toString().substring(0,1));
       mExpiryDate.setSelection(mExpiryDate.getText().toString().length());
    } else {
       mExpiryDate.setText("");
       mExpiryDate.setSelection(mExpiryDate.getText().toString().length());
       Toast.makeText(getApplicationContext(), "Enter a valid month", Toast.LENGTH_LONG).show();
    }
} else if (s.length() == 1){
    int month = Integer.parseInt(input);
    if (month > 1) {
       mExpiryDate.setText("0" + mExpiryDate.getText().toString() + "/");
       mExpiryDate.setSelection(mExpiryDate.getText().toString().length());
    }
}
else {

}
mLastInput = mExpiryDate.getText().toString();
return;