How to get all keys of HashMap

HashMap keyset() method is used to get all keys from hashmap java

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

public class HashMapGetAllKeys {

public static void main(String[] args) {

Map<Integer,String> hm = new HashMap<Integer,String>();

/*
* Associates the specified value with the specified key in
this map (optional operation). If the map previously
contained a mapping for the key, the old value is
replaced by the specified value
*/
hm.put(1,"ankush");
hm.put(2, "amit");
hm.put(3,"shivam");
hm.put(4,"ankit");
hm.put(5, "yogesh");

/*
* Returns a Set view of the keys contained in this map
*/

Set<Integer> keys =hm.keySet();

for (Integer key : keys) {
System.out.println(" key ="+key);
}
}

}

Output:

key =1
key =2
key =3
key =4
key =5

A Guide to HashMap                                                                                                            Java Doc – HashMap

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