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

joe darcy joe.darcy at oracle.com
Thu Apr 21 16:25:27 UTC 2016


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


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.



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

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