java - CompletableFuture allof timeout handling

Question

The effect you want to achieve: If the future collection does not return within 3 seconds, the completed future will be extracted.

Compilation error, "Cannot infer functional interface type."

Answer 1

The problem with the compilation error is that the subject did not pay too much attention. This can be easily checked.
You can see the red area of ​​the error report, which is the second parameter of the applyToEither method. Then check it applyToEither Parameter format of method

public <U> CompletableFuture<U> applyToEither(
        CompletionStage<? extends T> other, Function<? super T, U> fn) {
        return orApplyStage(null, other, fn);
    }

The second parameter is a Function. What Function requires is to return a result based on a parameter. However, the question clearly states that there are no parameters. It is written as a Supplier. Of course, the parameter type is not Meet the requirements of method applyToEither