Java 使用方括号将 Short 转换为 Integer

Question

I have the following code that has primitive wrapper classes:

// setValue expects Integer (class)
// getValue returns Short (class)
intLength.setValue(shortLength.getValue());

Netbeans flags this as an error "incompatible types: Short cannot be converted to Integer", and I get a compile error, which makes sense.

However if I add an extra set of brackets:

// setValue expects Integer (class)
// getValue returns Short (class)
intLength.setValue((shortLength.getValue()));

The error disappears and the code compiles and works. Can anyone tell me what the extra brackets are doing/why do the brackets do the casting. Thanks.

Answer 1

So as Andreas told in the comments; It's a NetBeans problem, NetBeans doesn't always follow the java specs, because if you checked the Java Language Specificate, Parenthesized Expressions , it doesn't change the type at all.

You can check that code manually, using javac and java commands and you'll receive a compilation error the both times.

Thanks to Andreas

Answer 2

short numShort = 15;
int numInt = (int) new Short(numShort);

or in your case

intLength.setValue( (int) new Short(shortLength.getValue()));