Auto Boxing and Unboxing

[Sharath Sri]

Hi,
I'm not getting a clear picture about the contexts of auto-boxing and auto-unboxing.
Is auto-boxing and auto-unboxing will happen in line of the corresponding primitive types or there are some exceptions to this.
I mean following things are possible with primitive types:
a) Unary and Binary Numeric Promotion.
c) Narrowing and Widening conversions.
Does the above conversions apply when autboxing and auto-unboxing happen.
Can some one please clarify.
Thanks in adavance.
Regards,
Sharath

[Jesper de Jong]

Autoboxing means converting a primitive type implicitly to an object (of one of the wrapper classes that corresponds to the primitive type that is converted), and autounboxing is ofcourse the opposite (implicitly converting an instance of a wrapper class to a primitive). These conversions are independent of promotions, narrowing and widening conversions, but ofcourse auto(un)boxing and the other conversions could be used together in one expression.

If you want to know the exact details, have a look at chapter 5 of The Java Language Specification, Conversions and Promotions. (Note, the JLS can be hard to read, but it is the official specification that describes everything into the finest details).