It is one of the most talked about features planned for Java: Closures. Many of us have been longing for them. Some of us (including I) have grown a bit impatient and have turned to scripting languages to fill the void.

But, once closures have finally arrived to Java: how will they effect the Java Community? Will the advancement of VM-targetted scripting languages slow to a crawl, stay the same, or acclerate? Will people flock to the new closure syntax, thus turning Java code-bases all-around into more functionally structured implementations? Will we only see closures sprinkled in Java throughout? What will be the effect on tool/IDE support? How about performance? And finally, what will it mean for Java's continued adoption, as a language, compared with other languages that are rising in popularity?

To provide an example of one of the latest proposed Java Closure syntax specs:

public interface StringOperation {
   String invoke(String s);
}

// ...

(new StringOperation() {
   public invoke(String s) {
       new StringBuilder(s).reverse().toString();    
   }
}).invoke("abcd");    

would become ...

String reversed = { 
    String s => 
    new StringBuilder(s).reverse().toString()
  }.invoke("abcd");

[source: http://tronicek.blogspot.com/2007/12/closures-closure-is-form-of-anonymous_28.html]