case expression

[cathymala louis]

Hi

why the following x4 constant can't be used in case expression.

final static Integer x4 = 8;

Thanks

[Mark Spritzler]

Depends on which version of Java you are using. It should work in Java 5.0 because of auto-boxing feature. Where in 1.4 you can only use the primitive int and not the Object Integer.

Mark

[cathymala louis]

As per K&B version 5 Chapter 5 question 13 tells like this.

A switch statement requries its case expression to be constant and wrapper variables(even static final ones) aren't consider constant.

I need more explanation.

[Krishnamoorthy Sethuraman]

Final wrapper variables cannot refer to different object once initialized, however the object itself can change. hence the primitive obtained out of auto-unboxing the wrapper is not a constant. Hence, wrapper variables are not allowed in the case expression. Not sure, whether this holds correct.