The toList() method of Collectors Class is a static (class) method. It returns a Collector Interface that gathers the input data onto a new list. This method never guarantees type, mutability, serializability, or thread-safety of the returned list but for more control toCollection(Supplier) method can be used. This is an un-ordered collector.
Syntax:
public static Collector<T, ?, R> toList()
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.
- toList():- Static method of Collectors class and returns a Collector interface object used to store a group of data onto a list. The Collectors class is under the java.util.streams package.
Return Value: This method returns a Collector which collects all the input elements into a List, in encounter order
Below are the examples to illustrate toList() method in Java:
Example 1:
// Java code to show the implementation of// Collectors toList() function import java.util.List;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 toList() function List<String> myList = s.collect(Collectors.toList()); // printing the elements System.out.println(myList); }} |
Output:
[Geeks, for, Lazyroar, Geeks Classes]
Example 2:
// Java code to show the implementation of// Collectors toList() function import java.util.List;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 toList() function List<String> myList = s.collect(Collectors.toList()); // printing the elements System.out.println(myList); }} |
Output:
[1, 2, 3, 4]