ReverseEcho.groovy

There’s a great line from the movie, The Truman Show, that explains why Truman never questioned his life circumstances: “We accept the reality of the world with which we’re presented.” It’s the same with Java. We didn’t know how tedious it was until Groovy showed us a better way.
Just how tedious is Java. Let’s look at an example that prints out the reverse of the command line arguments (e.g. “This is a test” prints out as “tset a si sihT”)

public class ReverseEcho {   public static void main(String[] args) {     for (int i = args.length - 1; i >= 0; i--) {       for (int j = args[i].length() - 1; j >= 0; j--) {         System.out.print(args[i].charAt(j));       }       System.out.print(" ");     }   } }

When you don’t know any better, well, that’s what you have to do: set up nested for loops and traverse in reverse. You’re happy as a bit in a bucket until Groovy comes along and presents a new reality.

args.reverseEach {   print "${it.reverse()} " }

Yep, Groovy really makes it that easy. args is an implicitly defined list that contains the command line arguments. reverseEach() is a shortcut (a concept mostly absent in Java) for reverse().each() and iterates over each element in the list in reverse order. reverse() is also a GDK method on string and does exactly what you might think, it creates a new string which is the reverse of the original.