default value in closure groovy code example

Example 1: groovy3 closure

{ item++ }                                          (1)

{ -> item++ }                                       (2)

{ println it }                                      (3)

{ it -> println it }                                (4)

{ name -> println name }                            (5)

{ String x, int y ->                                (6)
    println "hey ${x} the value is ${y}"
}

{ reader ->                                         (7)
    def line = reader.readLine()
    line.trim()
}

Example 2: groovy3 closure

{ [closureParameters -> ] statements }