Why is this Java code in curly braces ({}) outside of a method?

Question

I am getting ready for a java certification exam and I have seen code LIKE this in one of the practice tests:

class Foo {       int x = 1;       public static void main(String [] args) {           int x = 2;           Foo f = new Foo();           f.whatever();       }       { x += x; }  // <-- what's up with this?     void whatever() {           ++x;           System.out.println(x);       }   } 

My question is ... Is it valid to write code in curly braces outside a method? What are the effects of these (if any)?

Answer 1

Borrowed from here -

Normally, you would put code to initialize an instance variable in a constructor. There are two alternatives to using a constructor to initialize instance variables: initializer blocks and final methods. Initializer blocks for instance variables look just like static initializer blocks, but without the static keyword:

{     // whatever code is needed for initialization goes here }  

The Java compiler copies initializer blocks into every constructor. Therefore, this approach can be used to share a block of code between multiple constructors.

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