Hashmap

Question

public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
HashMap<String, Integer> ages = new HashMap<>();
ages.put("Tom", 22);
ages.put("Nick", 30);
ages.put("Eric", 44);
String[] nameArr = new String[ages.size()];
nameArr = ages.keySet().toArray(nameArr);
int ageLimit = sc.nextInt();
for (String emp : nameArr) {
if (
ages.get(emp) < ageLimit) {
ages.remove(emp);
}

}
System.out.println(ages);
}
}

Guys, for what I need the String " nameArr = ages.keySet().toArray(nameArr); " ?
It get only the key word from hashmap and add it to array "nameArr"?

Answer 1

Yes. It is getting the keys of the hashmap `ages` and putting them into the array `nameArr`

`ages.keySet()` returns a `Set` of keys of the hasmap, that is ("Tom", "Nick", "Eric").
Then calling the toArray() method on the `Set` puts the elements of the set into the array passed as argument.

Just a side note, instead of
`nameArr = ages.keySet().toArray(nameArr);`
You can just do
`ages.keySet().toArray(nameArray)`

As the .toArray() method makes changes directly to the array. So you don't need to assign it. It works currently because the .toArray() method returns the array passed as argument after making the changes.

Answer 2

also this is shorter
ages.values().removeIf( age -> age < ageLimit);