# IntFunction與UnaryOperator的用法

IntStream stream = IntStream.of (1,2,3);
IntFunction<IntUnaryOperator> inFu= x -> y -> x*y;//line n1
IntStream newStream = stream.map(inFu.apply(10));//line n2
newStream.forEach(System.out::print);

## Which modification enables the code fragment to compile?
A. Replace line n1 with:
IntFunction<UnaryOperator> inFu = x -> y -> x*y;
**B. Replace line n1 with:**
IntFunction<IntUnaryOperator> inFu = x -> y -> x*y;
C. Replace line n1 with:
BiFunction<IntUnaryOperator> inFu = x -> y -> x*y;
D. Replace line n2 with:
IntStream newStream = stream.map(inFu.applyAsInt (10));
- [x] **Answer: B**

[參考網站](https://magiclen.org/ocpjp-intfunction-unaryoperator/)

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###### tags: `ocpjp`