How to Get Head Map from Java TreeMap

The example aims to get a head map of TreeMap whose keys are less than the specified key by headMap method in Java.

Source Code

package com.beginner.examples;

import java.util.SortedMap;
import java.util.TreeMap;

public class GetHeadMapFromTreeMap {

	public static void main(String[] args) {
		
		//create TreeMap.
		TreeMap treeMap = new TreeMap();
		
		treeMap.put("1","Alice");
		treeMap.put("2","Bob");
		treeMap.put("3","Jack");
		
		/*
		 * To get a Head Map from Java TreeMap using headMap method of Java TreeMap.
		 */
		SortedMap sortedMap = treeMap.headMap("3");
		
		System.out.println("Head Map Contains : " + sortedMap);

	}

}

Output:

Head Map Contains : {1=Alice, 2=Bob}

References

Imported packages in Java documentation:

TreeMap
SortedMap