[java] LawOfDemeter: False positive for standard UTF-8 charset name

[mcandre]

Affects PMD Version:

6

Rule:

LawOfDemeter

Description:

PMD's application of the Law of Demeter considers it a violation to query the standard name of the Java UTF-8 character set. Unless the character set is assigned to an explicit variable name first.

Code Sample demonstrating the issue:

public final class Fib {
    /** utility class */
    private Fib() {}

    public static void main(final String[] args) throws IOException {
        System.out.print("N = ");

        try (Scanner scanner = new Scanner(System.in, StandardCharsets.UTF_8.name())) {
            final int n = scanner.nextInt();
            System.out.println(String.format("Fib %d = %d", n, fib(n)));
        }
    }
}

As a workaround, I am disabling this rule in my rulesets.xml:

<rule ref="category/java/design.xml">
    <exclude name="LawOfDemeter" />
</rule>

Running PMD through: [CLI | Ant | Maven | Gradle | Designer | Other]

Gradle

[jsotuyod]

@mcandre thanks for the report. Effectively, public constants are intended to be used this way, so it's probably safe to whitelist them (at least 1 level).

I can see the same thing happening with enums: MyEnum.SOMETHING.ordinal().

[linusjf]

You could create an instance variable (in your case, a static one) that points to StandardCharsets.UTF_8.name() and that would resolve this false positive.
#2179

[jsotuyod]

This is fixed in PMD 7.0.0-rc1. It won't be backported to PMD 6.