Question

how would I increment the key [i] by 1 in this situation every time I run through this for loop with the way I currently have it set up all the elements only get mapped to 1. I am trying to find out how many times each number occurs. I have tried +1 in the empty spot after list.get(i) but again only maps each element to 1. thank you.

    List<Integer> list = new ArrayList<Integer>();
    HashMap<Integer,Integer> Mode = new HashMap<Integer, Integer>();
    for (int i = 0; i < arr.length; i++) {
        for (int j = 0; j < arr[i].length; j++) {
            list.add(arr[i][j]); 
        }
    }
    System.out.println(list);
    int count = 1;
    for(int i = 0; i < list.size(); i ++) {
        Mode.put(list.get(i), );

Answer 1

If you have the option, you may find it easier to use something like Multiset from Guava.

Multiset<Integer> seen = HashMultiset.create();
for (int[] row : arr) {
  for (int elem : row) {
    seen.add(elem); // none of that nasty dealing with the Map
  }
}
// you can look up the count of an element with seen.count(elem)
E mostCommon = null;
int highestCount = 0;
for (Multiset.Entry<Integer> entry : seen.entrySet()) {
  if (entry.getCount() > highestCount) {
    mostCommon = entry.getElement();
    highestCount = entry.getCount();
  }
}
return mostCommon; // this is the most common element