TreeMap sort by values in java

Let’s learn TreeMap sort by values in java.

TreeMap sort by values in java

TreeMap stores key-value pairs which are in sorted order based on key. To sort a treemap by value we have to build some logic using comparator class. Here’s an example on how to sort a treemap by value.

import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
public class TreeMapByValue 
{
   public static <K, V extends Comparable<V>> Map<K, V> sortValues(final Map<K, V> m) 
   {
      Comparator<K> com = new Comparator<K>()
      {
         public int compare(K k1, K k2) 
         {
            int compare = m.get(k1).compareTo(m.get(k2));
            if(compare == 0)
            {
               return 1;
            }
            else
            {
               return compare;
            }
         }
      };
      Map<K, V> sortedByValues = new TreeMap<K, V>(com);
      sortedByValues.putAll(m);
      return sortedByValues;
   }
   public static void main(String[] args) 
   {
      TreeMap<String, String> fruits = new TreeMap<String, String>();
      fruits.put("K1", "Jackfruit");
      fruits.put("K2", "Raspberry");
      fruits.put("K3", "Kiwifruit");
      fruits.put("K4", "Tangerine");
      fruits.put("K5", "Strawberry");
      // calling sortvalues method
      Map<String, String> sortedMap = sortValues(fruits);
      Set set = sortedMap.entrySet();
      Iterator iterate = set.iterator();
      // print elements
      while(iterate.hasNext()) 
      {
         Map.Entry ma = (Map.Entry)iterate.next();
         System.out.print(ma.getKey() + ": ");
         System.out.println(ma.getValue());
      }
   }
}

Output:

K1: Jackfruit
K3: Kiwifruit
K2: Raspberry
K5: Strawberry
K4: Tangerine