In Android, how to make Login button disable with respect to EditText?

Question

If EditText is empty then Login Button has to be disabled. And if EditText has some texts then Login Button has to be ena

Answer 1

I only want to add that the check will NOT work if the InputType of the EditText is a password (or similar) and the fuction to proof the length of the text (see other answers) is called from

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

So it is important to call the check from

@Override 
public void afterTextChanged(Editable s) {...}