Collectors toSet() returns a Collector that accumulates the input elements into a new Set. There are no guarantees on the type, mutability, serializability, or thread-safety of the Set returned. This is an unordered Collector i.e, the collection operation does not commit to preserving the encounter order of input elements.
Syntax:
public static <T> Collector<T, ?, Set<T>> toSet()
where:
- T: The type of the input elements.
- Interface Collector<T, A, R>: A mutable reduction operation that accumulates input elements into a mutable result container, optionally transforming the accumulated result into a final representation after all input elements have been processed. Reduction operations can be performed either sequentially or in parallel.
- T: The type of input elements to the reduction operation.
- A: The mutable accumulation type of the reduction operation.
- R: The result type of the reduction operation.
- Set: A collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element.
Return Value: A Collector which collects all the input elements into a Set.
Below are the examples to illustrate toSet() method:
Example 1:
// Java code to show the implementation of// Collectors toSet() function  import java.util.Set;import java.util.stream.Collectors;import java.util.stream.Stream;  class GFG {      // Driver code    public static void main(String[] args)    {        // creating a Stream of strings        Stream<String> s = Stream.of("Geeks",                                     "for",                                     "Lazyroar",                                     "Geeks Classes");          // using Collectors toSet() function        Set<String> mySet = s.collect(Collectors.toSet());          // printing the elements        System.out.println(mySet);    }} |
Output:
[Geeks Classes, Lazyroar, Geeks, for]
Example 2:
// Java code to show the implementation of// Collectors toSet() function  import java.util.Set;import java.util.stream.Collectors;import java.util.stream.Stream;  class GFG {      // Driver code    public static void main(String[] args)    {          // creating a Stream of strings        Stream<String> s = Stream.of("1", "2", "3", "4");          // using Collectors toSet() function        Set<String> mySet = s.collect(Collectors.toSet());          // printing the elements        System.out.println(mySet);    }} |
Output:
[1, 2, 3, 4]
