Question

Is there a way to use anonymous code blocks in Groovy? For example, I’m trying to translate the following Java code into Groovy:

{
  int i = 0;
  System.out.println(i);
}
int i = 10;
System.out.println(i);

The closest translation I can come up with is the following:

boolean groovyIsLame = true
if (groovyIsLame) {
  int i = 0
  println i
}
int i = 10
println i

I know anonymous code blocks are often kind of an antipattern. But having variables with names like “inputStream0” and “inputStream1” is an antipattern too, so for this code I’m working on, anonymous code blocks would be helpful.

Answer 1

You can use anonymous code blocks in Groovy but the syntax is ambiguous between those and closures. If you try to run this you actually get this error:

Ambiguous expression could be either a
parameterless closure expression or an
isolated open code block; solution:
Add an explicit closure parameter
list, e.g. {it -> …}, or force it to
be treated as an open block by giving
it a label, e.g. L:{…} at line: 1,
column: 1

Following the suggestion, you can use a label and it will allow you to use the anonymous code block. Rewriting your Java code in Groovy:

l: {
  int i = 0
  println i
}
int i = 10
println i