Java tutorial
import java.util.TreeMap; public class Main { public static void main(String[] args) { TreeMap<String, String> treeMap = new TreeMap<String, String>(); System.out.println("Size of TreeMap : " + treeMap.size()); treeMap.put("1", "One"); treeMap.put("2", "Two"); treeMap.put("3", "Three"); System.out.println("Size of TreeMap after addition : " + treeMap.size()); treeMap.remove("2"); System.out.println("Size of TreeMap after removal : " + treeMap.size()); } }