CODEWITHSUNDEEP
javaandroidregex
Violet Giraffe
Violet Giraffe

Reputation: 33589

How to validate string being typed in EditText without discarding intermediate strings?

I'm trying to use TextWatcher and regex for validating user input. Note that I have a complex regex:

edit.addTextChangedListener(new TextWatcher() {           
            private final Pattern m_regex = Pattern.compile("([a-zA-Z]{4}[ ]{0,1}){7}");

            @Override
            public void afterTextChanged(Editable s) {
                  String text = s.toString();
                  int length = text.length();

                  if(!m_regex.matcher(text).matches() && length > 0) {
                       s.delete(length - 1, length);
                  }
            }

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

        });

The problem here is matcher can only check for 2 string states: match and no match with expression provided, but for input validation you also need to check for intermediate state - when a string doesn't match the pattern but doesn't contradict it either. Is there any way I could use my regex for validating string being typed in EditText?

Upvotes: 1

Views: 386

Answers (1)

Gabber
Gabber

Reputation: 5452

Do a match against another regex. Sorry if the answer seems silly, but as you said before, matcher can only check for 2 string states: match and no match.

EDIT:

I understood better your question. You can do this: test the input versus this regex

^(([a-zA-Z]{4}[ ]{0,1}){0,6}([a-zA-Z]{0,4})|([a-zA-Z]{4}))$

this will validate the text as being inserted. If it is ok let the user continue. Your regex should be used only when the user has finished to input text! -

OR, if you want to check if the user has finished to write do this: match the regex I wrote to see if the text is correct. If ok match yours and, if it matches, the user has finished inserting text.

Upvotes: 1

Related Questions