Sorting 2d arraylist based on two elements

Question

I am trying to sort a 2d Arraylist based on the 1st element and when comparing if the two elements are the same then sort it by the 2nd element.

So my Arraylist looks like

[[1, 4, 0], [2, 5, 2], [3, 5, 3], [4, 3, 6]]

and I want it too look like this

[[4, 3, 6], [1, 4, 0], [2, 5, 2], [3, 5, 3]]

This is my ArrayList

ArrayList<ArrayList<Integer>> processes = new ArrayList<>();

This is what I have so far using selection sort

int smallInt;
int j;
int smallIntIndex;
for(int i = 1; i<=processes.size();i++){
    smallInt = processes.get(i-1).get(1);
    smallIntIndex = i-1;
    for(j=i;j<processes.size();j++){
        if(processes.get(j).get(1)==smallInt){
          //not exactly sure what goes in here
        }else if(processes.get(j).get(1)<smallInt){
            smallInt = processes.get(j).get(1);
            smallIntIndex = j;
        }
    }
    ArrayList<Integer> temp = processes.get(smallIntIndex);
    processes.set(smallIntIndex,processes.get(i-1));
    processes.set(i-1,temp);
}

Answer 1

Are the labels (eg 1 or 2 or 3 - first / second / third entry) from a restricted set (eg only digits)? If so (as I think it is), you can sort them by applying Radix sort .