sortByFrequency

package ch.fhnw.claudemartin;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;

public class SomeClass {

  public static void main(final String[] arrg) {
    final int[] arr = { 2, 5, 2, 8, 5, 6, 8, 8 };
    System.out.println(Arrays.toString(sortByFrequency(arr)));
  }

  static final int[] sortByFrequency(final int[] input) {
    final Map<Integer, Integer> map = new TreeMap<Integer, Integer>();
    for (final int i : input) {
      if (map.get(i) == null) {
        map.put(i, 1);
      } else {
        int count = map.get(i);
        map.put(i, ++count);
      }
    }

    final List<Entry<Integer, Integer>> list = new ArrayList<>(map.entrySet());
    list.sort(Collections.reverseOrder(Entry.comparingByValue()));
    return list.stream().mapToInt(e -> e.getKey()).toArray();

  }

}