Sort Array by content inside Object inside Array

Question

@Override
    public String createExport(ArrayList<Integer> allIdList) {

        ArrayList<Answer> allAnswer = new ArrayList<>();
        for(int elem : vvtList) {
            allAnswer.addAll(findById(elem).getAnswer());
        }

        for(Answer elem : allAnswer) {
            allAnswer.sort(elem.getFirstSortId());    //Doesn't work
            allAnswer.sort(elem.getSecondSortId());   //Doesn't work
        }

        return allAnswer.toString;

    }

I created my own class Anwser. It contains two Integers, firstSortId and secondSortId. I want to sort the allAnswer-ArrayList by them. At the moment the Array List is pure chaos.

firstSortId 76 secondSortId 2
firstSortId 57 secondSortId 1
firstSortId 36 secondSortId 2

The result should be

firstSortId 57 secondSortId 1
firstSortId 36 secondSortId 2
firstSortId 76 secondSortId 2

How can I sort the array by one, and then by two Integers inside them?