Collectors.toSet()
does not preserve order. I could use Lists instead, but I want to indicate that the resulting collection does not allow element duplication, which is exactly what Set
interface is for.
Collectors.toSet()
does not preserve order. I could use Lists instead, but I want to indicate that the resulting collection does not allow element duplication, which is exactly what Set
interface is for.
You can use toCollection
and provide the concrete instance of the set you want. For example if you want to keep insertion order:
Set<MyClass> set = myStream.collect(Collectors.toCollection(LinkedHashSet::new));
For example:
public class Test {
public static final void main(String[] args) {
List<String> list = Arrays.asList("b", "c", "a");
Set<String> linkedSet =
list.stream().collect(Collectors.toCollection(LinkedHashSet::new));
Set<String> collectorToSet =
list.stream().collect(Collectors.toSet());
System.out.println(linkedSet); //[b, c, a]
System.out.println(collectorToSet); //[a, b, c]
}
}