Beyond all evil: Javas definition of an object

April 9, 2008 by Michael

Some days i ago, i decided to revamp my ambitions to get the scjp thingy done. What exactly for, i don’t know. But working to the self tests, i found the following:

class Ring {
  final static int x2 = 7;
  final static Integer x4 = 8;
  public static void main(String[] args) {
    Integer x1 = 5;
    String s = "a";
    if(x1 < 9) s += "b";
    switch(x1) {
      case 5: s += "c";
      case x2: s += "d";
      case x4: s += "e";

Questions is: Some arbitrary output or a compilation error and if, on which line.

Answer: Compilation fails due an error on line 11. What the frag? The obviously totally retarded switch statement can only handle constant values in its branches. So what? x4 is declared final static, as constant as it can be in Java. But no… Because its a big difference between int and Integer and due to the auto boxing and unboxing in Java 5 and up, the object Integer isn’t constant opposed to the scalar int.

Summary: A big deal with the SCJP is to teach the contestants how to work around some brain dead things in Java. Don’t get me wrong, i actually like Java, but the more i do in Ruby and the likes, the more some concepts in Java seem and are just wrong, like the for example not being all things equally objects.

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