try catch - Why is declaration required in Java's try-with-resource

Question

Java7's try-with-resources is great and all, but I can't wrap my head around why it is required to include the declaration of the resource in the try statement. My gut says the following should be possible:

CloseableResource thing;
try (thing = methodThatCreatesAThingAndDoesSomeSideEffect()) {
    // do some interesting things
}
thing.collectSomeStats();

Alas, this results in a syntax error (cryptically expecting a ;). Moving the type definition/declaration into the try statement works, which of course moves thing into the corresponding scope. I can figure out how to work around this when I want more from my AutoClosable than getting closed, I'm interested in why the compiler requires it like this.

Answer 1

Since Java 9 you can declare and initialize the variable used inside try-with-resources outside the block. The only additional requirement for variable is that it has to be effectively final.
So now it is possible to do:

CloseableResource thing = methodThatCreatesAThingAndDoesSomeSideEffect();
try (thing) {
    // do some interesting things
}
thing.collectSomeStats();

Hope it helps.