GOTO for Java

PHP has finally taken the plunge into the 1960s by implementing GOTO. Here's an implementation for Java.

This stupid hack was inspired by

• This (joke) implementation of GOTO for JavaScript
• This (joke) comment by VirtualCtor
• The (serious) inclusion of GOTO in PHP

       1 public class GotoDemo {
       2     public static void main(String[] args) {
       3         int i = 3;
       4         System.out.println(i);
       5         i = i - 1;
       6         if (i >= 0) {
       7             GotoFactory.getSharedInstance().getGoto().go(4);
       8         }
       9         
      10         try {
      11             System.out.print("Hell");
      12             if (Math.random() > 0) throw new Exception();            
      13             System.out.println("World!");
      14         } catch (Exception e) {
      15             System.out.print("o ");
      16             GotoFactory.getSharedInstance().getGoto().go(13);            
      17         }
      18     }
      19 }

Running it:

$ java -cp bin:asm-3.1.jar GotoClassLoader GotoDemo           
   3
   2
   1
   0
   Hello World!

I spent all of 30 minutes on this, so there are some caveats:

• No computed goto.
• Jumping past a variable definition will cause the verifier to reject your class, if you're lucky.
• It doesn't even handle packages properly; I didn't bother to swap dots and slashes.
• All classes must be compiled with line number information.

Source code here. Requires the ASM library.