LoginDialogFragment.java

/**
 * Returns true if the username and password pass validation.
 * 
 * @return False if the username or password is blank
 */
private boolean hasErrors() {
    boolean hasErrors = false;
    Drawable errorIcon = getErrorDrawable();
    String errorText = null;
    if (username.getText().length() == 0) {
        errorText = getString(R.string.enter_a_username);
        username.setError(errorText, errorIcon);
        hasErrors = true;
    }

    if (password.getText().length() == 0) {
        errorText = getString(R.string.enter_a_password);
        password.setError(errorText, errorIcon);
        hasErrors = true;
    }

    return hasErrors;
}