IntelliJ IDEA inspection warning argument might be null

Question

Is there any way to tell IDEA that the following is OK:

public static void main(String[] args) {
    String stringValue = args.length > 0 ? args[0] : null;
    long longValue;
    try {
        longValue = Long.parseLong(stringValue);
    } catch (NumberFormatException e) {
        throw new IllegalArgumentException("hmm...", e);
    }
    System.out.println(longValue);
}

It insists on highlighting stringValue and warning "Argument stringValue might be null". I know it might, but if it is, the exception will be caught.

Answer 1

Well, is it really OK? You are essentially using the exception to control the flow of the code. This is generally considered an anti-pattern ( Why not use exceptions as regular flow of control? ).

It can easily be avoided by doing the null check yourself:

if (stringValue != null) {
  longValue = Long.parseLong(stringValue);
}

However, if you want to keep your code the way it is and let the null case be handled by the parseLong() method, you can:

Annotate your method with @SuppressWarnings("ConstantConditions")

@SuppressWarnings("ConstantConditions")
public static void main(String[] args) {
  String stringValue = args.length > 0 ? args[0] : null;
  long longValue;
  try {
    longValue = Long.parseLong(stringValue);
  } catch (NumberFormatException e) {
    throw new IllegalArgumentException("hmm...", e);
  }
}

Add a comment //noinspection ConstantConditions

public static void main(String[] args) {
  String stringValue = args.length > 0 ? args[0] : null;
  long longValue;
  try {
    //noinspection ConstantConditions
    longValue = Long.parseLong(stringValue);
  } catch (NumberFormatException e) {
    throw new IllegalArgumentException("hmm...", e);
  }
}

---

IntelliJ helped me with both these by pressing alt + enter , bringing up the intentions menu where you can either choose Supress for method or Supress for statement .

However, I think both of these are IDE-specific, so my advise would simply be to let the warning be. Or even better, do the null check yourself.