Q:

Creation of Lists with different sizes inside a list - Main list with sublists and subsub lists inside

Basically I am trying to obtain prices of a particular application  for 7 different dates , sort the dates in ascending order and re-assign the corresponding prices with new sorted dates.
So, I want to create a main list with sublists inside something like 
[[Dates], [sorted Dates], [[pricesOfDay1],[pricesOfDay2],[pricesOfDay3]]] in java8.
I am able to create 
[[Dates], [sorted_Dates], [pricesOfDay1,pricesOfDay2,pricesOfDay3]]

by using 
List<List<String>> ListOfTariffSlots = new ArrayList<List<String>>();

But is it possible to create separate list for each day prices but still inside a list? I don't want all the prices as elements in a single list. I want them as elements of a sublists but inside a list. 
I hope this is now clear. Kindly let me know if more is required.
All possible suggestions are welcome

A:

Thank you all. But it was still not as expected. I have created a logic I guess this is similar with my requrement.
I have now created a list of prices as :
List<Object> priceList = null;

then in every date, which I did in a loop, I instantiated price list as 
priceList = new ArrayList<Object>();

and then in every list of the loop where I extracted prices for a particular day, I added it to the main priceList Object
priceList.add(price);

for(Element el : PriceLabels) {
//do something
//extract "price" list
}

In the above line, "price" is a list and "priceList" is also a list. That is, a list(priceList) holding another list(price). 
Then in the final step, I added this "priceList" to the superlist "ListOfTariffSlots".
ListOfTariffSlots.addAll((Collection<? extends List<Object>>) priceList);

I think this works for the requirement. I understand that it was not very clear for many of you. But thank you all for all your suggestions. It helped me to come up with this solution.

