While I was thinking the same thing as Sean/Stuart, it's not clear how
much risk you would be refactoring a lot of code just to use this
language feature.
It's pretty clear (to me anyway) what you were intending here.
Brad
On 6/28/2011 1:31 PM, Stuart Marks wrote:
On 6/28/11 11:46 AM, Sean Mullan wrote:
On 6/27/11 9:29 PM, Xuelei Fan wrote:
webrev: http://cr.openjdk.java.net/~xuelei/7059709/webrev.00/
It seems you could restructure this code by moving the instantiation
of the
FileInputStream down just before the KeyStore.load and use a
try-with-resources
block instead.
I had thought of this too but using try-with-resources for either of
these cases isn't obvious.
One difficulty is that the FileInputStreams are only initialized if some
condition is true, otherwise they're left null. That is, simplified,
FileInputStream fis = null;
if (...condition...) {
fis = ...initialization...
}
// process fis if non-null
To use try-with-resources, you'd have to do something like put the
conditional within the initialization expression. The only way to do
this in-line in Java is to use the ternary (?:) operator, like so:
try (FileInputStream fis = ...condition... ? ...initialization... : null) {
// process fis if non-null
}
or the conditional could be evaluated prior to the try, with the
resource variable being an alias:
FileInputStream fis = null;
if (...condition...) {
fis = ...initialization...
}
try (FileInputStream fis2 = fis) {
// process fis2 if non-null
}
or even by refactoring the conditional initialization into a separate
method:
try (FileInputStream fis = openFileOrReturnNull(...)) {
// process fis if non-null
}
Another approach would be to call KeyStore.load() from the different
condition arms, instead of conditionally initializing a variable:
if (...condition...) {
try (FileInputStream fis = ...initialization...) {
ks.load(fis, passwd);
}
} else {
ks.load(null, passwd);
}
This initializes the input streams closer to where they're used, but
this might change the behavior if an error occurs while opening the
stream; additional initializations or even side effects might occur
before the error is reached. I haven't inspected the code thoroughly to
determine whether this is the case. It also puts big initialization
expression into the t-w-r, which might be ugly.
Now, as you might know, I'm a big fan of try-with-resources, but using
it here brings in a potentially large restructuring. This might or might
not be warranted for this particular change; I don't know the tradeoffs
involved in this code.
s'marks
