Program: Basic TreeMap Operations.

Below example shows basic operations on TreeMap like creating an object, adding key-value pair objects, gtting value by passing key object, checking whether the map has elements or not, deleting specific entry, and size of the TreeMap.

package com.java2novice.treemap;

import java.util.TreeMap;

public class MyBasicOperations {
	
	public static void main(String a[]){
		TreeMap<String, String> hm = new TreeMap<String, String>();
		//add key-value pair to TreeMap
		hm.put("first", "FIRST INSERTED");
		hm.put("second", "SECOND INSERTED");
		hm.put("third","THIRD INSERTED");
		System.out.println(hm);
		//getting value for the given key from TreeMap
		System.out.println("Value of second: "+hm.get("second"));
		System.out.println("Is TreeMap empty? "+hm.isEmpty());
		hm.remove("third");
		System.out.println(hm);
		System.out.println("Size of the TreeMap: "+hm.size());
	}
}

{first=FIRST INSERTED, second=SECOND INSERTED, third=THIRD INSERTED}
Value of second: SECOND INSERTED
Is TreeMap empty? false
{first=FIRST INSERTED, second=SECOND INSERTED}
Size of the TreeMap: 2