Get max date from string array

[stefano.passiatore]

Hi, I've a table with a varchar column with an array of dates like this: ["31-12-2015","31-01-2016","31-12-2016"]

I need to get max date in my report. With expression editor I can get the array by this 

SUBSTITUTE(SUBSTITUTE($F{dateProroga},"[",""),"]","").split(",")[/code]

But I don't know how to get the max date (31-12-2016).

Any suggestion?

Thanks

Stefano