Run code only once!
Project hosted on github: https://github.com/claudemartin/LockOnce
It’s just one single utility class to make sure code is run only once. And then there’s another one for easy “Lazy Initialization”.
I once wrote this for Java 7 but now it needs Java 8. It makes much more sense to use this with Lambdas. It’s a bit like the lazy keyword of Scala.
// declaration of lazy field:
final Supplier<Foo> lazy = Lazy.of(() -> ...);
// Access to the data:
Foo foo = lazy.get();
You can also register a “destructor”. This solves the problem that such fields (they are usually
static final) are never GCd and finalizers are utterly useless. In the same way you can have resources (they just have to implement
AutoClose) closed on shutdown.
There already is
sun.misc.Cleaner. And Java 9 should even have
java.util.Cleaner or something like that. I simply didn’t know. So it’s better to wait for Java 9 or use
If you are still interested:
I have a blog post about Finalizers and PhantomReferences:
I did this because
EnumSet is in fact a bit set (if it’s not a
JumboEnumSet) but it can’t be used as such. I ended up writing a complete library for domain bit sets.
Project website: http://claude-martin.ch/enumbitset/
Project home @ GitHub: https://github.com/claudemartin/enum-bit-set
So there’s a class named Class. But it represents interfaces, annotations and enums too. What’s up with that?
Continue reading “Misnomer: The class named Class”
Some think “List” is a misnomer. I don’t even mind so much. I think List is ok.
I just put this here because there already is an entry in the FAQ:
Why don’t you rename the List interface to Sequence; doesn’t “list” generally suggest “linked list”? Also, doesn’t it conflict with java.awt.List?
PS: Vector is strange, though. It is synchronized and it really should be
SynchronizedList. But it is defacto deprecated. So who cares?
RuntimeException is thrown at runtime, right?
Continue reading “Misnomer: RuntimeException”
Java does not have pointers. Variables are of primitive or reference type. So it uses references. Then why is there a NullPointerException?
Continue reading “Misnomer: NullPointerException”
The final keyword creates a lot of confusion in the Java world. I’ll try to clear things up a bit. Continue reading “Misnomer: final keyword”
So this is my wordpress blog. I like programming. Computers understand me. But sometimes I like to write something down for other humanoids to read.