Groovy Category Annotation

Annotations really provides a whole new view of programming things. Groovy also provides some of its own annotations one of them is Category. Lets take an example of using it. We create a IntegerUtil class and annotate it with Category.

class IntegerUtil {
    List<Integer> multiples(Integer upto) {
        (1..upto).collect {this * it}

Now the above code made your class any other groovy category class for example Time Category. Now you can use these methods as follows -:

List<Integer> multiples
use(IntegerUtil) {
    multiples = 2.multiples(10)
println multiples  // Output -: [2, 4, 6, 8, 10, 12, 14, 16, 18, 20]

It really helps when you want some more helper methods on already existing classes.

Hope it helps
Uday Pratap Singh


Hope it helps
Uday Pratap Singh

One thought on “Groovy Category Annotation

  1. Pingback: Using Category in groovy - Grails Info

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