Scala, sugar in Java : intro

2010/06/15 | Published in ,

Few days ago (one month) at the first meeting of PSUG (Paris Scala User Group), I notice that lot of member need a smooth way to explore, to learn and to use scala and why scala could be interesting. As I can’t do lot of speech, I decide to start by writing some mini-articles… and first step was to ReBoot the personnal site/blog.

To try to achieve the goal, I’ll writing a serie of mini-article about scala for java developper, where I plan to expose syntax sugar and pattern, not all but enough to start writing scala code, like java code but with scala sugar.

In this serie (and the rest of the blog), I’ll try to use the following tools and conventions :

  • maven 3.x / mvnshell to build project via cli (Command Line Interface)
  • eclipse (3.6) + m2eclipse (0.10) + scala-ide (2.8.0) + m2eclipse-scala
  • scala coding convention from : http://davetron5000.github.com/scala-style/

hope to be helpfull.

The first sugar : * no declaration of exception in method signature => no need to wrap to match signature (dictated by interface, framework) * remove ‘;’ at end of line * type inference => no need to double write Type

// Java
  public Xvz doSomething() throws AbcException {
    Xyz v = new Xzy(...);
    v.doStuff();
    return v;
  }

// Scala (step 1)
  public def doSomething() : Xvz = {
    val v : Xyz = new Xzy(...);
    v.doStuff();
    return v;
  }

// Scala (step 2) : remove implicit syntax (public, ; , return)
  def doSomething() : Xvz = {
    val v : Xyz = new Xzy(...)
    v.doStuff()
    v
  }

// Scala (step 3 ) : type inference
  def doSomething() = {
    Xyz v = new Xzy(...)
    v.doStuff()
    v
  }