Question

I want to allow users to create a username using only alphanumeric characters but where the alpha characters can be any of the characters in the user’s native language. It must be possible to restrict the input to only those characters that are part of the alphabet of the native language or if there is no alphabet in a language (like Chinese), then limited to those characters that would normally be considered non-symbolic (symbolic characters being a question mark, colon, etc).

Using inputType seems to pose a problem because setting it to “text” actually allows the keyboard to display symbols as well.

Answer 1

EditText editText = (EditText)findViewById(R.id.your_edit_text); 

editText.addTextChangedListener(new TextWatcher() {
@Override
public void afterTextChanged(Editable arg0) {
    // TODO Auto-generated method stub
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
    // TODO Auto-generated method stub
}
@Override
public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
    for(int i=0;i<arg0.toString().length();i++){
        if(arg0.toString().charAt(i)=='a char you hate')
            //Show an error and change the contents of arg0
    }
}
});

---

EDITED

I have edited the answer a little bit because In the previous version assumed that he changed the last character. However this is not true onTextChanged is called even if he inserted a character in the middle of the String.