Cada vez que escriba en un EditText 4 caracteres se ponga un espacio

editText.addTextChangedListener(new TextWatcher() {
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        String text = editText.getText().toString();
        int len = text.length();
        if(len == 4){
            editText.setText(editText.getText().toString() + " ");
            editText.setSelection(editText.getText().length());
        }
    }
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) { }
    @Override
    public void afterTextChanged(Editable s) { }
});