如何在Java中绑定通用类型以仅接受Integer和Double

Question

private <T extends Number> T method(T param){...}

This will accept AtomicInteger, AtomicLong, BigDecimal, BigInteger, Byte, Double, Float, Integer, Long, Short.

I want to only accept Double, Integer, Float.

Answer 1

You can't bound the generic type like this, because Integer , Double and Float are final . Therefore, they can't be extended.

You can overload three methods:

private Integer method(Integer param){...}

private Double method(Double param){...}

private Float method(Float param){...}

Answer 2

I dont believe there is a way to do it via generics (since those types you wanted are siblings).

I would instead just overload the method to take in those different parameters. It will look the same to each client, and also, the compiler will give you an error if the client tried to call the method with a wrong type.