TreeMap size() method in java

import java.util.TreeMap;
public class TreeMapSizeMethodExample
{
   public static void main(String[] args)
   {
      TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
      tm.put(32, "pineapple");
      tm.put(51, "watermelon");
      tm.put(38, "grapes");
      tm.put(69, "mango");
      tm.put(58, "apple");
      System.out.println("Given TreeMap is: " + tm);
      System.out.println("size of TreeMap is: " + tm.size());
   }
}