Re: Check if a final field is initialized
On Tue, 23 Jan 2007 23:00:06 +0100, Daniel Dyer <"You don't need it"> =
wrote:
On Tue, 23 Jan 2007 21:54:02 -0000, Stefan Z Camilleri =
<szc001@szc001.com> wrote:
Hi
I am creating a singleton that shall be accessed by multiple threads,=
=
possibly simultaneously... here is my code
public class FooEngine implements FooInterface {
private static final m_barElement;
public static FooInterface getBarInstance() {
synchronized (BarElement) {
if (null == m_barElement) m_barElement = new FooEngine();
}
return m_barElement;
}
}
Somehow I need to check if m_barElement is initialized... in C# I =
generally check for null, yet in Java it seems as though I have to =
explicitly initialize it to null... but this would then mean that I =
cannot assign it to an instance later.
Setting it to an instance of FooEngine at declaration is not an optio=
n =
since FooEngine requires lots of other preparatory work prior to it's=
=
being instantiated.
But it will not be instantiated until the class is loaded. Classes in=
=
Java aren't loaded until they are needed, so you effectively get lazy =
=
initialisation for free. Unless there are other static members of the=
=
class that are accessed before the call to getBarInstance(), the class=
=
won't be loaded until the point at which the getBarInstance() invocati=
on =
occurs.
Dan.
Thanks Dan... that makes perfect sense!
Thanks again!
-- =
- Stefan Z Camilleri
- www.szc001.com
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