使用collect闭包方法在groovy中填充HashMap

Question

I am trying to populate a Map from an List. Here's what I am doing.

itemNoList = [1,2,3,4]
bookMap = [:]
bookMap = itemNoList.collect{ [ (it) : it+1 ] }

When I do this, the bookMap changes to ArrayList type and now has a List of HashMap.

bookMap is now [{1=2}, {2=3}, {3=4}, {4=5}] , ie a List of Maps.

How would I be able to get a HashMap from the ArrayList using collect method? It would be easy to solve this by using an each instead collect , but I'm just curious whether it could be solved using collect .

Answer 1

You're in luck! The collectEntries method handles works just like collect but for a Map!

groovy:000> itemNoList = [1, 2, 3, 4]
===> [1, 2, 3, 4]
groovy:000> itemNoList.collectEntries { [(it): it+1] }
===> {1=2, 2=3, 3=4, 4=5}