Re: Constructor
Tom Anderson wrote:
On Fri, 26 Sep 2008, zerg wrote:
Andrea Francia wrote:
public class Main {
static Foo escaped;
static class Foo {
public Foo() {
escaped = this; // escaping! don't do this at home!
throw new RuntimeException();
}
}
public static void main(String[] args) {
try {
Foo foo = new Foo();
} catch (RuntimeException e) {
System.out.println("This reference escaped from constructor:"
+ escaped);
}
}
}
I think you'll find that the above code won't compile. Your IDE or
javac will complain about the use of "this" inside the constructor,
other than for constructor chaining (e.g. "this(args);").
I think you'll find it won't.
Tom and Andrea are (unfortunately) correct.
Note that this kind of escape is a bad idea even if the constructor will
(eventually) succeeed, since it makes a partially constructed object visible
to other threads. NetBeans used to use a pattern like this for its
DataObjects (roughly, objects that represent a file known to the IDE)
abstract class DataObject
{
protected DataObject()
{
register(this); // add this to the global list of DataObjects
}
}
The result, that other threads in the IDE would now see partially
constructed objects, caused intermittent and intractable problems. I don't
know (and don't at this point really much care) whether this has been fixed.
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