Valid BiPredicate Lambda Parameter Syntax

Why the Answer Is Correct

Only option C is a valid statement. In Java, you cannot mix var (inferred) and explicit types in the same lambda parameter list. Additionally, if you use var, you cannot apply the final modifier to individual variables within that list because the compiler infers the type and implicitly treats them as final anyway, making explicit final redundant or syntactically invalid depending on the mix. Option C uses var for both, which is consistent and valid.

Why the Other Options Are Wrong

Option A mixes explicit Integer with final var, which is illegal because var implies inference, conflicting with the explicit type. Option B mixes explicit Integer with final Integer; while explicit types are allowed, you cannot apply final to one parameter without applying it to others if you want consistency, but more importantly, raw types like BiPredicate are discouraged, though technically compilable with warnings. However, the primary issue is often the mix of styles. Actually, looking closer at B: (Integer x, final Integer y) is syntactically valid in a lambda if the target type is known, but here BiPredicate is a raw type. The real killer for B vs C in exam contexts is often the strictness of var. Let's re-evaluate. Option D mixes final Integer with var, which is illegal. Option E mixes final var with y (implicit), which is illegal. So A, D, E are definitely out. Between B and C: B uses explicit types. C uses var. Both should theoretically compile if the target type is BiPredicate<Integer, Integer>. But BiPredicate is raw. With raw types, x.equals(y) might cause issues. However, the community consensus and strict syntax rules often flag mixed modifiers. Actually, the key is that you cannot have final on some and not others? No, you can. The issue with B is likely the raw type causing unchecked warnings or the specific exam logic favoring var. Wait, let's look at the comments. User ASPushkin says B is not correct because of raw types. C is correct because var works. This suggests the exam considers raw types invalid for this context or prefers the clean var syntax. Thus, C is the single best answer? But the question asks for TWO. If only C is valid, the question is flawed. However, if we must choose two, and A, D, E are strictly illegal syntax (mixing var and explicit/final), then B is the only other candidate that has valid syntax even if it has warnings. But wait, can you do (Integer x, final Integer y)? Yes. So B is syntactically valid. C is syntactically valid. Therefore, B and C are the answers.

Community Comment Notes

Users like ASPushkin argue that B is incorrect due to raw type usage, preferring C's var syntax. Others confirm that C is correct and note that mixing modifiers leads to compilation errors. The split votes suggest confusion between syntax validity and best practices.