How to use stringBuilder

Question

I have a function and Technical Leader review code and said : Why this if statement? It's basically the same message. If you want customized, use a string builder with the type. How to change it , can someone help me?

private Optional<String> validatePrimaryPath(SalesChannelType salesChannelCode, List<String> primaryPathList) {

  if (CollectionUtils.isEmpty(primaryPathList)) {
    if (salesChannelCode.equals(SalesChannelType.HEB_TO_YOU)) {
      return Optional.of("Customer Hierarchy is mandatory field for HebToYou.");
    } else {
      return Optional.of("Customer Hierarchy is mandatory field.");
    }
  }

  return Optional.empty();
}

Answer 1

To prevent writing the same (partial) string literal multiple times, you can:

• Use a constant for the common part:

  if (CollectionUtils.isEmpty(primaryPathList)) {
      final String COMMON = "Customer Hierarchy is mandatory field";
      if (salesChannelCode.equals(SalesChannelType.HEB_TO_YOU)) {
          return Optional.of(COMMON + " for HebToYou.");
      } else {
          return Optional.of(COMMON + ".");
      }
  }
  

• Build the string using StringBuilder:

  if (CollectionUtils.isEmpty(primaryPathList)) {
      StringBuilder buf = new StringBuilder("Customer Hierarchy is mandatory field");
      if (salesChannelCode.equals(SalesChannelType.HEB_TO_YOU)) {
          buf.append(" for HebToYou");
      }
      return Optional.of(buf.append('.').toString());
  }
  

Personally, I would keep the code in the question, especially if you ever might need support non-English versions of the text, because in other languages the extra text might not go there.