I thought today's meeting was pretty good. Based on one of the discussion points, I wanted to try putting together an interface that described the boot paradigm. Unfortunately even in Java 8 it doesn't work too well, I cannot assign a static variable in an interface the way I can in an abstract class. More importantly, it doesn't give us the private level expectation I would look for in this case. I best I could come up with using an interface is:
public interface CDIBooter {
default BeanManager initialize() {
return initialize(new HashMap<>());
}
BeanManager initialize(Map<?,?> properties);
void shutdown();
class BootHolder {
static CDIBooter instance = null;
}
static CDIBooter instance() {
if(BootHolder.instance == null) {
ServiceLoader<CDIBooter> serviceLoader = ServiceLoader.load(CDIBooter.class);
for(CDIBooter booter : serviceLoader) {
BootHolder.instance = booter;
break;
}
}
return BootHolder.instance;
}
}
where as the abstract class is a bit briefer, while also being private.
public abstract class CDIBooter {
public BeanManager initialize() {
return initialize(new HashMap<>());
}
public abstract BeanManager initialize(Map<?,?> properties);
public abstract void shutdown();
private static CDIBooter instance = null;
public static CDIBooter instance() {
if(instance == null) {
ServiceLoader<CDIBooter> serviceLoader = ServiceLoader.load(CDIBooter.class);
for(CDIBooter booter : serviceLoader) {
instance = booter;
break;
}
}
return instance;
}
}
Obviously ignore concurrency issues, etc. It does look to be safer to do an abstract class, rather than a factory-interface.
John