How to count duplicate elements in ArrayList?

Question

I need to separate and count how many values in arraylist are the same and print them according to the number of occurrences.

I\'ve got an arraylist called digits :<

Answer 1

Java 8, the solution: 1. Create Map when the Key is the Value of Array and Value is counter. 
2. Check if Map contains the Key increase counter or add a new set.

 private static void calculateDublicateValues(int[] array) {
      //key is value of array, value is counter
      Map map = new HashMap();

      for (Integer element : array) {
        if (map.containsKey(element)) {
          map.put(element, map.get(element) + 1); // increase counter if contains
        } else
          map.put(element, 1);
      }

      map.forEach((k, v) -> {
        if (v > 1)
          System.out.println("The element " + k + " duplicated " + v + " times");
      });

    }