Tagged In java :
Relaxing visibilities using Javassist
I personally like to restrict the visibility of my classes and members as much as possible. However, package-private classes get quickly annoying when used in an interactive environment such as the Scala interpreter. When we encountered this problem with one of our internal tools, we decided to generate derived versions of our JAR files with… Read more
When Garbage Collection is Failure
For systems that absolutely require a constant responsiveness Java is generally not an option because of the pauses associated with the garbage collector. Even the alternative collectors, such as parallel and concurrent-mark-sweep, have a pause associated with them for major and minor collections. This problem can be avoided, though, by making sure the garbage collector… Read more
Type inference puzzler
Does this compile? public class Puzzle { static Object one() { return 1; } static <T> T safeOne() { return (T) one(); } public static void main(String[] args) { int one = safeOne(); System.out.println(one); } } Take a look at it carefully and think before answering. Why or why not? Once you’ve thought it through,… Read more
Creating TypeLiterals in Scala
In case anyone wondered, here is how one can easily create instances of Google Guice’s TypeLiteral in Scala. Type literals are used for reifying types. def typeLiteralOf[T](implicit m: scala.reflect.Manifest[T]): TypeLiteral[T] = (m match { case m: ClassManifest[T] if m.typeArguments.isEmpty => TypeLiteral.get(m.erasure) case m: ClassManifest[T] => TypeLiteral.get(new ParameterizedTypeImpl(m.erasure, m.typeArguments.map { case n: ClassManifest[_] => typeLiteralOf(n).getType }.toArray))… Read more
Type Safe Bit Fields Using Higher-Kinded Polymorphism
Refering to securities, such as stocks or bonds, is far from standard. We all know Apple’s ticker AAPL; But what about the Oracle of Omaha’s company Berkshire Hathaway? Google says BRKA, Yahoo! BRK-A, Bloomberg BRK/A and Reuters BRKa. Due to these oddities, every serious automated trading system like kaChing’s has at its core a powerful… Read more
I Can Has Invariant Mapz?
If I had to pick one of the major source of bugs in large refactorings I recently went through, it would probably be the bunch of methods in the java.util.Map interface which are contravariant on the key type. For instance, one can retrieve an element from a map using a supertype of its key type… Read more