Validating EditText View on TextChanged

Question

I am trying to put some constraints on my EditText field in my app. For the fullname and some other fields, I would like to only allow letters, space and some other characters like '.' or '-'.

I saw some stuff online and put this together:

mFullnameView = (EditText) findViewById(R.id.activity_register_et_fullname);
TextWatcher fullnameTextWatcher = new TextWatcher() {
    @Override
    public void afterTextChanged(Editable s) {
        validate(s.toString());
    }

    @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 void validate(String s) {
        if (!(Pattern.matches("^[A-Za-z\\s]{1,}[\\.]{0,1}[A-Za-z\\s]{0,}$", s))) {
            if (s.length() > 0) {
                final String cleanText = s.substring(0, s.length());
                mFullnameView.setText(cleanText);
            }
        }
    }
};

However now my app freezes for a few seconds and then crashed when I try typing a "." in the EditText field, I do not know why this happens or how to resolve it.

It might be easier to just restrict what the user can enter into the EditText to begin with, so that you don't have to try to validate. Like here: http://stackoverflow.com/a/23212485/2128028 — Everett, Mar 21 '17 at 01:18

score 1 · Accepted Answer · answered Mar 21 '17 at 01:38

If you change the text in TextWatcher , the method in TextWatcher will callback again. So , you should avoid recursive calls or use InputFilter.

    InputFilter[] filters = new InputFilter[1];
    filters[0] = new InputFilter() {
        @Override
        public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
            if (source == null) return null;
            Pattern p = Pattern.compile("^[A-Za-z\\s]{1,}[\\.]{0,1}[A-Za-z\\s]{0,}$");
            Matcher m = p.matcher(source.toString());
            StringBuilder builder = new StringBuilder();
            while (m.find()) {
                builder.append(m.group());
            }
            return builder.toString();
        }
    };
    mFullnameView.setFilters(filters);

Validating EditText View on TextChanged

1 Answers1