OT2004 : Taming the Tiger (Java 1.5)

This session was presented by Benedict Heal, and he was brilliant; concise, clear, humourous and extremely chilled out. Even the fact that Josh Bloch was listening in on his presentation didn't phase him.

Most of the new Java 1.5 features are already widely known. Generics, annotations, auto-boxing, enums, syntactic sugar, yada yada yada.

Some things that caught my eye:

• -Xlint : a compiler flag to warn you when your code can be improved to take advantage of new features such as generics.
• Generics are not available at runtime (unlike C#).
• Use of generics all over the API, not just collections. For example, Class is a genericised type, so newInstance() returns the correct type.
• List<MyThing> cannot be given a List<ExtendedMyThing>. Makes sense really as otherwise you'd be able to add things that it shouldn't allow.
• Genericised types can be constrained to only allow certain type. class Blah<T extends MyThing>.
• Wildcards allow even more flexibility: List<? extends MyThing> list = new ArrayList<ExtendedThing>() // valid.
• Or this: List<? super ExtendedThing> list = new ArrayList<MyThing>(); // valid
• Generics are complicated :)
• Annotations can be specified as source level, class level (available for inspection by class loader) or runtime level (available through reflection).
• Variable parameters to a method. Defined like this: printf(String format, Object... args). The three dots are part of the syntax! Called like this: out.printf("Blah blah blah", 44, "hello", someObject). Note autoboxing comes into play too.

It's only a shame there isn't a feature such as the anonymous delegate in C#... now that is real power. Rock on Java 1.8.

Comments

jez

Yeah, Benedict rocks! He did one of the best jsig.com presentations so far, a couple of years ago ( http://209.235.197.109/seminars/2002/London/14May2002.html )

Thanks for all the updates on the OT Conference, they've been cool joe.

Keith Lea

You should fix your angle brackets in #4

ben

Tsk tsk, Joe... an XML guru like yourself putting in bare angle brackets instead of the appropriate entities... ;-) (i.e. all your generics examples above aren't coming through the html...)

Joe Walnes

D'oh! Thanks for pointing that out, Ben.

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