code: private boolean checkField(EditText editText) {
          boolean valid = true;
          if (TextUtils.isEmpty(editText.getText())) {
              editText.startAnimation(mWiggle);
              editText.requestFocus();
              valid = false;
          }
          return valid;
      }
docs: Check if the edit text is valid or not.
  
  @param editText field to check.
  @return true if the edit text isn't empty