问题
What does @ means before a field name in Groovy? For some classes I am able to access private fields that are not directly accessible, let's take ComposedClosure for example:
public class Person {
private String name
}
def u = new Person(name:"Ron")
println u.@name //Ron
println u.name //Ron
a = {2} >> {3}
println a.@first //first closure object
println a.first //runtime error
回答1:
It allows you to override groovy's use of property accessors. If you write:
println u.name
groovy will invoke the automatically generated getter Person.getName(). If you write:
println u.@name
it will go directly to the field like it would in Java. In the case of the closure, it seems to have a first field but not a corresponding getFirst accessor.
In the groovy manual, it's documented as the direct field access operator.
回答2:
It means you're accessing a field directly, rather than going through a getter.
See the Groovy operator docs, although there isn't much more to say. Other than probably avoid it.
The reason it fails for a ComposedClosure is because there's no getter for first (or second).
来源：https://stackoverflow.com/questions/8319403/groovy-symbol-before-fields