[java:S1170] FP when field is initialized by static input

[mfroehlich (Marvin Fröhlich)]

The following code produces a FP from Java rule S1170.

private static long nextID = 1L;
private final long localID = nextID++; // FP

The rule suggests to make this final field static, too. But obviously it cannot be static.

[Colin]

Hey @mfroehlich

I think you know the template at this point.

How to Report a False-positive / False-negative

Hey SonarSource Community! False-positives happen, as do false-negatives, and we’re eager to fix them. We are thrilled when our users report problems, so we can make our products better. What is a false-positive (FP)? A false-positive is when an issue is raised unexpectedly on code that should not trigger an issue, or where the suggested action doesn’t make any sense for the code. What is a false-negative (FN)? A false-negative is when an issue should be raised on a piece of code, but isn’t…

What product(s) are you using and what version?

[mfroehlich (Marvin Fröhlich)]

Ah, sorry, yes.

Qube: Community 9.9

[Margarita_Nedzelska]

Hey @mfroehlich,

Thanks for your report. If I’m not mistaken the rule checks that the field is not used in non-static members and fields, so it can be static.

In your case, it’s hard to say anything if the field can be static because we need to examine the whole class. If you’re suggesting that the rule should also take into consideration the name, then I think local is a bit confusing as it might not refer to the “unique for instance”, but something else.

If you feel that this is an FP, please, provide the full class, and the explanation.

Best,
Margarita

[mfroehlich (Marvin Fröhlich)]

Sorry, my example was indeed not sufficient. You don’t need the complete class though. And no, I’m not suggesting to evaluate the name.

public class C
{
    private static long nextID = 1L;
    private final long localID = nextID++; // FP
    
    public int getID()
    {
        return localID;
    }
}

So, the rule would just need to look at the whole class, and if the field is used in a non static context.

[Margarita_Nedzelska]

Thanks for the detailed report, I was able to reproduce the issue. This is a quite old rule and in indeed doesn’t check if the field is used in non-static members. I created a ticket to fix it:

https://sonarsource.atlassian.net/browse/SONARJAVA-4749

Best,
Margarita