1.Spreading Operator:扩展操作符 *

class Car{
    String make
    String model
}

def cars = [
    new Car(make:'BenChi',model:'101'),
    new Car(make:'BaoMa', model:'102'),
　　 null
]

def makes = cars*.make

println makes

/*Output
['BenChi', 'BaoMa', null]
*/

2扩展操作符 *可以使用在任何实现了Iterable的类中

class Component{
    Long id
    String name
}

class CompositeObject implements Iterable<Component>{
    def components = [
        new Component(id:1, name:'Foo'),
        new Component(id:2, name:'Bar')
    ]
    
    @Override
    Iterator<Component> iterator(){
        components.iterator()
    }
}

def composite = new CompositeObject()
println composite*.id
println composite*.name

/*Output
[1, 2]
[Foo, Bar]

*/