groovy - lazy instantiation of the map value -

is there way instantiate value of map lazy?

for example

class maptest {     @lazy(soft = true) hashmap<string, list<string>> map }

doing can use call , null without recieving nullpointerexception

new maptest().map.key1

however attempt call

map.key1.remove(1)

will lead nullpointerexception due value being null. (it fine if threw indexoutofbounds exception)

is there way instantiate list value of map?

try map.withdefault :

def map = [:].withdefault { [] } assert map.key1.isempty()

some explanation :

[:] groovy way instantiate empty hash map
withdefault groovy method on map wich take closure. closure call every time key requested initialize value if doesn't exist. closure take 1 parameter (the key) , should value
[] groovy way create empty list - { [] } closure wich return empty list every key

see others examples here

Ben