import java.util.LinkedList;
import java.util.TreeSet;

/*
 * Example of retainAll(Collection<?> c) method.
 */
public class TreeSetExample
{
    public static void main( String[] args )
    {

        TreeSet<Integer> treeSet = new TreeSet<Integer>();

        treeSet.add(40);
        treeSet.add(20);
        treeSet.add(30);
        treeSet.add(100);
        treeSet.add(200);

        System.out.println("treeSet : " + treeSet + "\n");

        LinkedList<Integer> linkedList = new LinkedList<Integer>();
        
        linkedList.add(100);
        linkedList.add(200);

        System.out.println("linkedList : " + linkedList + "\n");

        /*
         * Retains only the elements in this set that are contained in the
         * specified collection (optional operation). In other words, removes
         * from this set all of its elements that are not contained in the
         * specified collection.
         * 
         * If the specified collection is also a set, this operation effectively
         * modifies this set so that its value is the intersection of the two
         * sets.
         */

        boolean isRetained = treeSet.retainAll(linkedList);

        System.out.println("isRetained : " + isRetained);
        System.out.println("treeSet : " + treeSet + "\n");
    }
}

Output