how to define a list of variable number of objects in groovy?

Question

I am learning groovy, I am using the documentation and some youtube videos. I want for testing to find out how to declare an array of objects, but that array will have a x number of objects depending on some stuff. Here is what I tried:

class Issue {
    String type = ""
    String severity = ""
    String linestart = "" 
    String filename = "" 
    String meesage = "" 
}

def test(){
    Issue[] Issues = new Issue[5] 
    Issues[0].type = "error"
    println Issues[0].type
}

test()

what I get:

Caught: java.lang.NullPointerException: Cannot set property 'type' on null object
java.lang.NullPointerException: Cannot set property 'type' on null object

I assume my array does not have 5 Issues objects inside, and that is why is trying to set on null object. How would be the right syntax to do so?

aldrin · Accepted Answer · 2021-04-15 16:31:31Z

1

You are right- all the values are initially null. You have to first create instances of Issue and assign it to the array elements,

Issues[0] = new Issue()
Issues[0].type = "error"

alternatively, using "groovy" syntax,

Issues[0] = new Issue(type: "error")

answered Apr 15, 2021 at 16:31

aldrin

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2 Comments

Jesus Fernandez Over a year ago

thanks for answering. I am wondering now if it is better to use a class or a map for this case...and how to create a list of maps

aldrin Over a year ago

peronally, i would use a list of objects here, List<Issue> issues You have a well defined class which is preferable to using a map of properties

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