Learn Java for Web Development

APPENDIX B: Introduction to Groovy 413

Listing B-20. Creating and Using Ranges

1. def numRange = 0..9


2. numRange.each {print it}


3. println ""


4. println numRange.contains(5)


5. def reverseRange = 9..0


6. reverseRange.each {print it}


7. def exclusiveRange = 1..<10


8. println ""


9. exclusiveRange.each {print it}


10. def alphabet = 'a'..'z'


11. println ""


12. println alphabet.size()


13. println alphabet[25]

   Lines 1, 5, 7, and 10 illustrate how to define ranges.

   Line 1 defines an inclusive range of numbers.

   Line 10 defines an inclusive range of lowercase letters.

   Line 7 defines an exclusive list of numbers. The range results in a range of

numbers 1 to 9, excluding 10.

   Line 5 creates a range in reverse order, 9 through 0. Frequently, ranges are used for

iterating. In Listing B-20, each() was used to iterate over the range. Listing B-21

shows three ways you can use a range to iterate: one in Java and two in Groovy.

0123456789

true

9876543210

123456789

26

z

Listing B-21. Iterating with Ranges

for (i in 0..9) {
println i
}
(0..9).each { i->
println i
}

The each() method is used to iterate through and apply the closure on every element.