Re: JDK 9 pre-review of JDK-6850612: Deprecate Class.newInstance since it violates the checked exception language contract

[joe darcy]

Hello,

After a generally positive reception, please review the webrev to 
implement the deprecation of Class.newInstance and the suppression of 
the resulting warnings:

    http://cr.openjdk.java.net/~darcy/6850612.0/

There are also some changes in the langtools repo; I'll send a separate 
review request for those changes to compiler-dev.

I'll also forward this review request to other areas with affected code.

Thanks,

-Joe

On 4/17/2016 10:31 AM, joe darcy wrote:
Hello,

With talk of deprecation in the air [1], I thought it would be a fine 
time to examine one of the bugs on my list

    JDK-6850612: Deprecate Class.newInstance since it violates the 
checked exception language contract

As the title of the bug implies, The Class.newInstance method 
knowingly violates the checking exception contract. This has long been 
documented in its specification:

Note that this method propagates any exception thrown by the nullary 
constructor, including a checked exception. Use of this method 
effectively bypasses the compile-time exception checking that would 
otherwise be performed by the compiler. The Constructor.newInstance 
method avoids this problem by wrapping any exception thrown by the 
constructor in a (checked) InvocationTargetException.

Roughly, the fix would be to turn the text of this note into the 
@deprecated text and to add a @Deprecated(since="9") annotation to the 
method. There are a few dozen uses of the method in the JDK that would 
have to be @SuppressWarning-ed or otherwise updated.

Thoughts on the appropriateness of deprecating this method at this time?

Comments on the bug have suggested that besides deprecating the 
method, a new method on Class could be introduced, 
newInstanceWithProperExceptionBehavior, that had the same signature 
but wrapped exceptions thrown by the constructor call in the same way 
Constructor.newInstance does.

Thanks,

-Joe

[1] 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-April/040192.html