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来自：think in java （3） 外文原文 The busy Java developers guide to Scala: Class action It makes sense for Java? developers to use objects as a first point of reference for understanding Scala. In this second installment of The busy Java developers guide to Scala series, Ted Neward follows a basic premise of language measurement: that the power of a language can be measured in direct relation to its ability to integrate new facilities -- in this case, support for complex numbers. Along the way youll see some interesting tidbits related to class definitions and usage in Scala. In last months article , you saw just a touch of Scalas syntax, the bare minimum necessary to run a Scala program and observe some of its simpler features. The Hello World and Timer examples from that article let you see Scalas Application class, its syntax for method definitions and anonymous functions, just a glimpse of an Array[], and a bit on type-inferencing. Scala has a great deal more to offer, so this article investigates the intricacies of Scala coding. Scalas functional programming features are compelling, but theyre not the only reason Java developers should be interested in the language. In fact, Scala blends functional concepts and object orientation. In order to let the Java-cum-Scala programmer feel more at home, it makes sense to look at Scalas object features and see how they map over to Java linguistically. Bear in mind that there isnt a direct mapping for some of these features, or in some cases, the mapping is more of an analog than a direct parallel. But where the distinction is important, Ill point it out. Scala has class(es), too Rather than embark on a lengthy and abstract discussion of the class features that Scala supports, lets look at a definition for a class that might be used to bring rational number support to the Scala platform (largely swiped from Scala By Example -- see Resources): Listing 1. rational.scala class Rational(n:Int, d:Int) { private def gcd(x:Int, y:Int)