Which of the following is not a functional interface in the java.util.function package?
A. BiPredicate B. DoubleUnaryOperator C. ObjectDoubleConsumer D. ToLongFunction
C.
The BiPredicate interface takes two generic arguments and returns a boolean value.
Next, DoubleUnaryOperator takes a double argument and returns a double value.
Last, ToLongFunction takes a generic argument and returns a long value.
That leaves Option C, which is the correct answer.
While there is an ObjDoubleConsumer functional interface,
which takes a generic argument and a double value and does not return any data,
there is no such thing as ObjectDoubleConsumer.
Remember that Object is abbreviated to Obj in all functional interfaces in java.util.function.