How to iterate over List in List

Question

I am solving a problem. Initially, I have to check what are the elements in this. So, how should I iterate over it????

//Complete the freqQuery function below.
static List<Integer> freqQuery(List<List<Integer>> queries){

}

Answer 1

static List<Integer> freqQuery(List<List<Integer>> queries) {
      queries.forEach(
            query-> query.forEach(
                         integer->/*do whatever you want*/ )
                     );
}

Answer 2

Use a foreach to take one by one the lists of integer, and, inside it, use another foreach to take all the integers:

for(List<Integer> lst : queries) {
   for (Integer i : lst) {
       System.out.println(i);
    } 
}