LinkedBlockingDeque retainAll() method in Java with Examples

The retainAll() method of LinkedBlockingDeque is an in-built function is Java which is used to remove from this deque all of its elements that are contained in the specified collection. That means, all the common elements these two collections are removed from this deque.

Syntax:

public boolean retainAll(Collection c)

Parameters: This method takes collection c as a parameter containing elements to be removed from this list.

Return Value: This method returns true if this deque changed as a result of the call.

Exceptions: This method throws NULL Pointer Exception if the specified collection is Null.

Below program illustrates the retainAll() function of LinkedBlockingDeque class:

Example 1:

// Java Program Demonstrate retainAll()
// method of LinkedBlockingDeque

import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {

        // Create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();

        // Add numbers to end of LinkedBlockingDeque
        LBD.add(11);
        LBD.add(22);
        LBD.add(33);
        LBD.add(44);

        // print deque
        System.out.println("Linked Blocking Deque: "
                           + LBD);

        // Create object of ArrayList collection
        ArrayList<Integer> ArrLis
            = new ArrayList<Integer>();

        // Add number to ArrayList
        ArrLis.add(55);
        ArrLis.add(11);
        ArrLis.add(23);
        ArrLis.add(22);

        // Print ArrayList
        System.out.println("ArrayList to be retained: "
                           + ArrLis);

        // Function retainAll() retains
        // all the common elements from deque
        LBD.retainAll(ArrLis);

        // Print deque
        System.out.println("Retained Linked Blocking Deque: "
                           + LBD);
    }
}

Output:

Linked Blocking Deque: [11, 22, 33, 44]
ArrayList to be retained: [55, 11, 23, 22]
Retained Linked Blocking Deque: [11, 22]

Example 2:

// Java Program Demonstrate retainAll()
// method of LinkedBlockingDeque

import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {

        // Create object of LinkedBlockingDeque
        LinkedBlockingDeque<String> LBD
            = new LinkedBlockingDeque<String>();

        // Add numbers to end of LinkedBlockingDeque
        LBD.add("geeks");
        LBD.add("Geeks");
        LBD.add("gfg");
        LBD.add("Gfg");

        // Print deque
        System.out.println("Linked Blocking Deque: "
                           + LBD);

        // Create object of ArrayList collection
        ArrayList<String> ArrLis
            = new ArrayList<String>();

        // Add elements to ArrayList
        ArrLis.add("GeeksforGeeks");
        ArrLis.add("Geeks");
        ArrLis.add("gfg");
        ArrLis.add("Gfg");

        // Print ArrayList
        System.out.println("ArrayList to be retained: "
                           + ArrLis);

        // Function retainAll() retains
        // all the common elements from deque
        LBD.retainAll(ArrLis);

        // Print deque
        System.out.println("Retained Linked Blocking Deque: "
                           + LBD);
    }
}

Output:

Linked Blocking Deque: [geeks, Geeks, gfg, Gfg]
ArrayList to be retained: [GeeksforGeeks, Geeks, gfg, Gfg]
Retained Linked Blocking Deque: [Geeks, gfg, Gfg]

Reference: https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/LinkedBlockingDeque.html#retainAll-java.util.Collection-