Detect usage of null parameter in Java?

SonarLint VS Code
1

Total newbie question here. I’m evaluating SonarLint v1.20.1 using Java and the VS Code extension. I was expecting that it would flag this as a possible null deference on value, but no warning is given.

String someFunction(String value) {
    return value.trim();
}

I am getting warnings about other issues so SL is running and finding useful things, Am I expecting too much here or is this just a misconfiguration or misunderstanding on my part?

Thanks!

2

Hi Jason, and welcome to our community,

Raising possible NPE issues on all method calls not having an explicit null check would be super annoying and noisy. A lot of code in Java implicitly assume method parameters are not null.

SonarLint will only report an issue when it has good enough indication that the de-referenced variable can be null.

Try:

  String someFunction(String value) {
    if (value == null) {
      return value.trim();
    }
    return value;
  }

or (using JSR 305 annotations)

  String someFunction(@Nullable String value) {
    return value.trim();
  }

You should then see issue reported.