Java OCA OCP Practice Question 3173

import java.util.Collection;
import java.util.Map;
import java.util.NavigableMap;
import java.util.TreeMap;

public class Main {
  public static void main(String[] args) {
    NavigableMap<String, Integer> grades = new TreeMap<String, Integer>();
    grades.put("A",  5); grades.put("B", 10); grades.put("C", 15);
    grades.put("D", 20); grades.put("E", 25);

    System.out.printf("1:%d, ", grades.get(grades.firstKey()));
    System.out.printf("2:%d, ", sumValues(grades.headMap("D")));
    System.out.printf("3:%d, ", sumValues(grades.subMap("B", false, "D", true)));
    grades.subMap(grades.firstKey(), false, grades.lastKey(), false).clear();
    System.out.printf("4:%d%n", sumValues(grades));
  }/*from  w  w  w.j a v a2s .c o m*/

  public static <K, M extends Map<K, Integer>> int sumValues(M freqMap) {
    Collection<Integer> values = freqMap.values();
    int sumValues= 0;
    for (int value : values)
      sumValues += value;
    return sumValues;
  }
}