#1370 false positive for unused method using method references in java 8

[Sebastian Hoß]

findbugs complains incorrectly that a private static method is not used. However this method is actually called using the new method reference syntax of Java 8. The workaround here is simple: replace the method reference with an actual method call. Example:

    public List<String> readLocations(final List<String> inputs) {
        return inputs.stream()
                .map(MyClass::createPath)
                // here comes more code..;
    }

    private static Path createPath(final String input) {
        // doesn't matter
        return null;
    }

The workaround replaces

.map(MyClass::createPath)

with

.map(input -> createPath(input))

[Tagir Valeev]

Testcase is committed:
https://code.google.com/p/findbugs/source/detail?r=5c9848da8e5ae79892545dd3689d7bc071413a3f

I cannot reproduce your problem in FB 3.0.1. Of course it persists in 3.0.0, but we've fixed it. Which version of FindBugs are you using?

[Sebastian Hoß]

You are right! I was using version 3.0.0 of the findbugs-maven-plugin. Switching to version 3.0.1 which was just released, fixes this problem. Thanks a lot!

[SRINIVAS MACHERLA]

In case of overloaded methods still findbugs reports same error. Its working only after I change the method name.

For below scenario, findbug reports UPM_UNCALLED_PRIVATE_METHOD.

    public List<String> readLocations(final List<String> inputs) {
        return inputs.stream()
                .map(MyClass::createPath)
                // here comes more code..;
    }

    private Path createPath(final String input) {
        // doesn't matter
        return createPath(input, 0);
    }

private Path createPath(final String input, final int d) {
        // doesn't matter
        return null;
    }

I'm able to unblock my self changing createPath(final String input) method name.

[SRINIVAS MACHERLA]

Reopened bug here https://github.com/spotbugs/spotbugs/issues/735