How to Apply the Textchange event on EditText

Question

I developed one simple app, like subtraction, addition. In this app I use three EditTexts, one for answer and other two for question. I want to calculate the answer of quest

Answer 1

I used this and it's correct:

public void afterTextChanged(Editable arg0) {
    String inputs = input.getText().toString();
    Integer index=0;
    if(!inputs.equals("")) 
        index=Integer.valueOf(inputs);

}