CODEWITHSUNDEEP
groovy
Vineela Durbha
Vineela Durbha

Reputation: 113

How to declare a string array in Groovy?

How can I declare a string array in Groovy? I am trying as below but it is throwing an error

def String[] osList = new String[]

No expression for the array constructor call at line:

What am i doing wrong?

Upvotes: 9

Views: 44211

Answers (3)

injecteer
injecteer

Reputation: 20707

A simple way is

String[] osList = []
assert osList.class.array
assert 'java.lang.String[]' == osList.class.typeName

Another question is that this definition is rather useless. This is an immutable zero-length String[] and can be used only as a constant somewhere.

Upvotes: 5

user9858935
user9858935

Reputation:

First of: welcome to SO!

You have a few options for creating arrays in groovy.

But let's start with what you've done wrong.

def String[] osList = new String[]

You used both def and String[] here.

Def is an anonymous type, which means that groovy will figure out which type it is for you. String[] is the declared type, so what groovy will see here is:

String[] String[] osList = new String[]

which obviously won't work.

Arrays however need a fixed size, which needs to be given as an argument to the creation of the Array:

Type[] arr = new Type[sizeOfArray]

in your case if you'd want to have 10 items in the array you would do:

String[] osList = new String[10]

if you do not know how many Strings you will have, use a List instead. An ArrayList will do for this in most cases:

List<String> osList = new ArrayList<>()

now you can add items by calling:

osList.add("hey!")

or using groovy's list-add operator:

osList << "hey!"

For further issues you should refer to groovy's official documentation and see if you can't find the solution yourself!

Upvotes: 9

Armando Carballo
Armando Carballo

Reputation: 111

​def arr = [] as String[]

or

String[] arr = [] as String[]

This should do it. You can test it and play around in here: https://groovyconsole.appspot.com/

Upvotes: 7

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