pDiscount.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void afterTextChanged(Editable editable) {
if (editable.toString().startsWith(".")){
pDiscount.setError("Can't start with "+editable.charAt(0));
pDiscount.setText("");
}
}
});