False positive on squid:S2275

[ShioT]

When passing an array as the second argument to String.format, SonarLint picks it up as me providing too few arguments.

• SonarLint for Eclipse 5.3.0.19940
• JDK8
• Spring Tool Suite 4 - 4.6.1.RELEASE

Code to reproduce:

String.format("%d%d", IntStream.range(0, 2).toArray());

// or

String.format("%d%d", IntStream.range(0, 2).toArray(Object[]::new));

[Quentin (Quentin Jaquier)]

Hello @ShioT,

I’m confused, when I run the first example, I have an error and I can not even compile the second one.
Is IntStream indeed from java.util.stream? Am I missing something?

That being said, I agree that String.format supports arrays as argument, so

String.format("%d and %d", getArray()); // S2275: not enough arguments. FP

Object[] getArray() {
  return new Object[]{1,2};
}

should not raise an issue.

I will probably create a ticket once we figure out what I missed from the initial post.

[ShioT]

Yes, IntStream is from the package you mentioned. It has been available since Java 8.

https://docs.oracle.com/javase/8/docs/api/java/util/stream/IntStream.html

What is the error that you are facing? If you can’t compile the second one, I think you might be using jdk 7 or earlier.

[Quentin (Quentin Jaquier)]

For the first one, I have a runtime exception:

IllegalFormatConversionException: d != [I

And for the second one, IntStream does not have toArray() with an argument.

For the record, I already created a ticket (SONARJAVA-3506), since without even considering your examples we already have misbehavior when an array is passed as an argument of format.

[ShioT]

Good to know, thanks. I am sorry that I have not verified my example; my actual (proprietary) code had some .map() in the middle of the stream operation and I did not realize that IntStream does not support Stream<Integer> methods. Adding a .mapToObj(Integer::valueOf) before .toArray() fixes the compilation problem (this time I have verified it):

String.format("%d%d", IntStream.range(0, 2).mapToObj(Integer::valueOf).toArray());
String.format("%d%d", IntStream.range(0, 2).mapToObj(Integer::valueOf).toArray(Object[]::new));

[Quentin (Quentin Jaquier)]

The problem behind is the same as the one I described in the ticket, I added the examples you shared there to be sure we correctly support them.

Thanks for coming back with precision.

Best,
Quentin