Hi,
On 04/19/2016 01:05 AM, Stuart Marks wrote:
On 4/17/16 10:31 AM, joe darcy wrote:
With talk of deprecation in the air [1], I thought it would be a fine
time to
"In the Spring a young man's fancy lightly turns to thoughts of
deprecation."
-- apologies to Tennyson
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: [...]
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.
Deprecating Class.newInstance() seems reasonable to me, for the
reasons you've stated.
It's not clear to me that a replacement method adds much value. I
believe it's possible to replace a call
clazz.newInstance() // 1
with the call
clazz.getConstructor().newInstance() // 2
which is only a bit longer. Both snippets are declared to throw
InstantiationException and IllegalAccessException. But snippet 2 also
is declared to throw InvocationTargetException and NoSuchMethodException.
This would seem to be an inconvenience, but *all* of these exceptions
are subtypes of ReflectiveOperationException. It seems pretty likely
to me that most code handles these different exception types the same
way. So it's fairly low cost to replace snippet 1 with snippet 2, and
to adjust the exception handling to deal with
ReflectiveOperationException. Thus I don't see much value in adding a
new method such as Class.newInstanceWithProperExceptionBehavior().
...except for performance. The Class.newInstance() does special
constructor and caller caching so that access checks don't have to be
performed at every invocation.
Performance sensitive user code using Class.newInstance() should then
probably be modified to obtain Constructor only once and then re-use it
for multiple invocations.
Regards, Peter
s'marks
