How to check in Groovy that object is a list or collection or array?

Question

The question is as simple as the title. How to check in Groovy that object is a list or collection or array? But can\'t find a simple way of checking it. Any ideas?

Answer 1

I don't know if you need to distinguish between Collection, List and Array, or just want to know if an object is any of these types. If the latter, you could use this:

boolean isCollectionOrArray(object) {    
    [Collection, Object[]].any { it.isAssignableFrom(object.getClass()) }
}

// some tests
assert isCollectionOrArray([])
assert isCollectionOrArray([] as Set)
assert isCollectionOrArray([].toArray())
assert !isCollectionOrArray("str")

Run the code above in the Groovy console to confirm it behaves as advertised