Groovy Closure

/*
  Closures
  A Groovy Closure is like a "code block" or a method pointer. It is a piece of
  code that is defined and then executed at a later point.

  More info at: http://www.groovy-lang.org/closures.html
*/
//Example:
def clos = { println "Hello World!" }

println "Executing the Closure:"
clos()

//Passing parameters to a closure
def sum = { a, b -> println a+b }
sum(2,4)

//Closures may refer to variables not listed in their parameter list.
def x = 5
def multiplyBy = { num -> num * x }
println multiplyBy(10)

// If you have a Closure that takes a single argument, you may omit the
// parameter definition of the Closure
def clos = { print it }
clos( "hi" )

//anonymous block of code
class Example {
   static void main(String[] args) {
      def clos = {println "Hello World"};
      clos.call();
   } 

}

// formal parameter in closure
class Example {
   static void main(String[] args) {
      def clos = {param->println "Hello ${param}"};
      clos.call("World");
   } 

}


//Closure and Variables
class Example {     
   static void main(String[] args) {
      def str1 = "Hello";
      def clos = {param -> println "${str1} ${param}"}
      clos.call("World");

      // We are now changing the value of the String str1 which is referenced in the closure
      str1 = "Welcome";
      clos.call("World");
   } 

}



//Closure in Methods
class Example { 
   def static Display(clo) {
      // This time the $param parameter gets replaced by the string "Inner"         
      clo.call("Inner");
   } 

   static void main(String[] args) {
      def str1 = "Hello";
      def clos = { param -> println "${str1} ${param}" }
      clos.call("World");

      // We are now changing the value of the String str1 which is referenced in the closure
      str1 = "Welcome";
      clos.call("World");

      // Passing our closure to a method
      Example.Display(clos);
   } 

}