Convert Map Values from HashSet to List in Java
The following code shows show to convert a map values of HashSet type into List/ArrayList in Java:
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class Test {
public static void main(String[] args) {
HashSet<String> fruits = new HashSet<>();
fruits.add("Grapes");
fruits.add("Mango");
fruits.add("Apple");
fruits.add("Papaya");
fruits.add("Pineapple");
HashSet<String> flowers = new HashSet<>();
flowers.add("Tulip");
flowers.add("Rose");
flowers.add("Sunflower");
flowers.add("Marigold");
Map<String, Object> map = new HashMap<>();
map.put("fruits", fruits);
map.put("flowers", flowers);
Set<String> newSet = new HashSet<>();
map.values().forEach(m->{
newSet.addAll((Set)m);
});
List<String> list = new ArrayList<>(newSet);
System.out.println(list);
}
}
Output:
[Apple, Tulip, Grapes, Papaya, Mango, Rose, Pineapple, Sunflower, Marigold]