CODEWITHSUNDEEP
grailsgroovy
Anonymous Human
Anonymous Human

Reputation: 1948

Groovy list sort on two criteria

I have a list of objects which are all the same type and have two properties a 'uniqueId', and a 'secondaryId'. I want to sort this list first by 'uniqueId' and then by 'secondaryId' for each uniqueId so that this list:

UniqueID/SecondaryID 5/3 2/6 5/8 2/5

once sorted will look like: 2/5 2/6 5/3 5/8

I can't seem to get the syntax quite right:

return searchResults.sort{[it.uniqueId, it.secondaryId]}

is what I am trying to start with but that didn't work.

Upvotes: 2

Views: 2069

Answers (1)

Will
Will

Reputation: 14519

You can use the elvis operator for a second sorting criteria:

map = [[u:5, s:3],
 [u:2, s:6],
 [u:5, s:8],
 [u:2, s:5]]

sort = { m ->
  m.sort { e1, e2 -> 
    e1.u <=> e2.u ?: e1.s <=> e2.s 
  } 
}

assert sort(map) == [[u:2, s:5], 
 [u:2, s:6], 
 [u:5, s:3], 
 [u:5, s:8]]

Upvotes: 9

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