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Overloading with varargs

 
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According to the K&S book (page 249)


In every case, when an exact match isn't found, the JVM uses the method with the smallest argument that is wider than the parameter



The above is correct if the parameters are primitives that are wider than the argument as in the following two examples:

Widening:


Widening & Boxing


Both the above two example output "in int" which is fine.

It is different though if the paramters are var-args. In the following example, the compiler complains that the paramters in the go() method are ambiguous.



Why does it not apply the same rules? Why does it not choose the smallest argument that is larger than the argument (i.e. int... in the above example) as in the previous examples?
 
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O. Ziggy wrote:
Widening & Boxing



This example is *not* widening and Boxing. Notice that the variable "b" is defined as an int primitive.

Widening followed by boxing is actually not supported for method parameter conversions according to the Java Language Specification.

Henry
 
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Henry Wong wrote:

O. Ziggy wrote:
Widening & Boxing



This example is *not* widening and Boxing. Notice that the variable "b" is defined as an int primitive.

Widening followed by boxing is actually not supported for method parameter conversions according to the Java Language Specification.

Henry



Sorry my mistake - This was meant to be just boxing as the int is boxed to Integer.
 
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O. Ziggy wrote:


Why does it not apply the same rules? Why does it not choose the smallest argument that is larger than the argument (i.e. int... in the above example) as in the previous examples?



BTW, this example has come up before -- I think it is related to the compiler not being about to choose the most-specific type between the two array types. I don't remember the discussion getting completely resolved, as the JLS seems to be somewhat obscure on how conversions are done with var-args, and other conversion options. I however, along with many, are in the camp that it is definitely a bug.

Henry
 
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Ok thanks Henry.
 
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yap it doesnt compile
 
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Has anyone got Java 7 installed on their machine? I am told that this does compile on Java 7 but not 6.
I am at work at the moment so i cant install JDK 7 on my work machine.

Thanks
 
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