Allow specific characters in EditText and block all other Characters Android

Question

I want to allow some specific characters in Edittext and block all other characters. I have searched the internet and didn't found a solution. All i found out was how to block specific characters but in my case i want to allow specific characters and block all other characters. For example the characters that i want to allow in edittext are A-Z, 0-9 and a comma, dot and underscore(_) that's it. If someone can give me an example of how to do that or point me to the right link i will be very grateful. Thanks!

Answer 1

One way to allow only certain characters is to use a TextChangedListener with a Pattern

final Pattern pAlpha = Pattern.compile("[0-9a-zA-Z,._]+");
yourEditText.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {}

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

    @Override
    public void afterTextChanged(Editable s) {
    if (pAlpha.matcher(yourEditText.getText()).matches()) {
        // you allowed it
    } else {
        // you don't allow it
    }

 }
});