In Groovy, you can sort an array in ascending or descending order using the sort() method. Here's an example:
// create an array of numbers
def numbers = [5, 2, 8, 1, 9]
// sort the array in ascending order
numbers.sort()
println numbers // output: [1, 2, 5, 8, 9]
// sort the array in descending order
numbers.sort { a, b -> b <=> a }
println numbers // output: [9, 8, 5, 2, 1]
In the above code, we created an array of numbers and sorted it using the sort() method. The first call to sort() sorts the array in ascending order. The second call to sort() specifies a closure that returns b <=> a, which sorts the array in descending order.