This method is used to retain all the elements present in the collection from the specified collection into the list.
Syntax:
boolean retainAll(Collection c)
Parameters: This method has only argument, collection of which elements are to be retained in the given list.
Returns: This method returns True if elements are retained and list changes.
Below programs show the implementation of this method.
Program 1:
// Java code to show the implementation of// retainAll method in list interfaceimport java.util.*;public class GfG { // Driver code public static void main(String[] args) { // Initializing a list of type Linkedlist List<Integer> l = new LinkedList<>(); l.add(1); l.add(3); l.add(5); l.add(7); l.add(9); System.out.println(l); ArrayList<Integer> arr = new ArrayList<>(); arr.add(3); arr.add(5); l.retainAll(arr); System.out.println(l); }} |
Output:
[1, 3, 5, 7, 9] [3, 5]
Program 2: Below is the code to show implementation of list.retainAll() using Linkedlist.
// Java code to show the implementation of// retainAll method in list interfaceimport java.util.*;public class GfG { // Driver code public static void main(String[] args) { // Initializing a list of type Linkedlist List<String> l = new LinkedList<>(); l.add("10"); l.add("30"); l.add("50"); l.add("70"); l.add("90"); System.out.println(l); ArrayList<String> arr = new ArrayList<>(); arr.add("30"); arr.add("50"); l.retainAll(arr); System.out.println(l); }} |
Output:
[10, 30, 50, 70, 90] [30, 50]
Reference:
Oracle Docs
