sort list by date in descending order - groovy madness

Question

I'm not able to sort a list of Objects by a Date in descending order

Let's say this is my class Thing

class Thing {

Profil profil
String status = 'ready'
Date dtCreated = new Date()
}

Inside the method I'm creating the List things

            List profiles = profil.xyz?.collect { Profil.collection.findOne(_id:it) }

            List things = []

and then I populate the list with each associated Thing of each profile

            profiles.each() { profile,i ->
                if(profile) {
                    things += Thing.findAllByProfilAndStatus(profile, "ready", [sort: 'dtCreated', order: 'desc']) as 
                 }

Alright, now things has a lot of things in it, unfortunately the [order: 'desc'] was applied to each set of things and iI need to sort the whole list by dtCreated. That works wonderful like

            things.sort{it.dtCreated}

Fine, now all the things are sorted by date but in the wrong order, the most recent thing is the last thing in the list

So I need to sort in the opposite direction, I didn't find anything on the web that brought me forward, I tried stuff like

            things.sort{-it.dtCreated} //doesnt work
            things.sort{it.dtCreated}.reverse() //has no effect

and I'm not finding any groovy approach for such a standard operation, maybe someone has a hint how I can sort my things by date in descending order ? There must be something like orm I used above [sort: 'dtCreated', order: 'desc'] or isn't it?

aduchate aduchate · Accepted Answer · 2013-06-20T21:31:15

Instead of

things.sort{-it.dtCreated}

you might try

things.sort{a,b-> b.dtCreated<=>a.dtCreated}

reverse() does nothing because it creates a new list instead of mutating the existing one.

things.sort{it.dtCreated}
things.reverse(true)

should work

things = things.reverse()

as well.

sort list by date in descending order - groovy madness

3 Answers