what are the different ways to create an Arraylist and Hashmap in groovy

Question

I have created an ArrayList like the following:

def list = new ArrayList()

But the codenarc report it is warning like following.

Answer 1

Typical is:

def list = []

other options include

def list = new ArrayList()
def list = new ArrayList()
List list = new ArrayList()
def list = [] as ArrayList
List list = [] as ArrayList

and of course:

List list = new ArrayList();

Similar options exist for HashMap using [:].