Program: How to get all keys from HashMap?

Below example shows how to get all keys from the given HashMap. By calling keySet() method, you can get set object with all key values.

package com.java2novice.hashmap;

import java.util.HashMap;
import java.util.Set;

public class MyHashMapKeys {
	
	public static void main(String a[]){
		HashMap<String, String> hm = new HashMap<String, String>();
		//add key-value pair to hashmap
		hm.put("first", "FIRST INSERTED");
		hm.put("second", "SECOND INSERTED");
		hm.put("third","THIRD INSERTED");
		System.out.println(hm);
		Set<String> keys = hm.keySet();
		for(String key: keys){
			System.out.println(key);
		}
	}
}

{second=SECOND INSERTED, third=THIRD INSERTED, first=FIRST INSERTED}
second
third
first