ConcurrentLinkedDeque offer() method in Java with Examples
The java.util.concurrent.ConcurrentLinkedDeque.offer() method is an inbuilt method in Java which inserts the specified element, passed as a parameter, to the deque.
Syntax:
public boolean offer(E elem)
Parameters: The method accepts a parameter elem which species the element to be inserted to the deque.
Return Value: The function returns True if the element is successfully added into the deque and returns False otherwise.
Exception: The function throws a NullPointerException if the passed parameter is NULL.
Below programs illustrate the ConcurrentLinkedDeque.offer() method:
Program 1:
// Java Program to Demonstrate offer()// method of ConcurrentLinkedDeque  import java.util.concurrent.*;  class GFG {    public static void main(String[] args)    {          // Creating an empty Deque        ConcurrentLinkedDeque<String> cld            = new ConcurrentLinkedDeque<String>();          // Add elements into the Deque        cld.add("Welcome");        cld.add("To");        cld.add("Geeks");        cld.add("4");        cld.add("Geeks");          // Displaying the Deque        System.out.println("ConcurrentLinkedDeque: "                           + cld);          // Insert an element using offer()        if (cld.offer("GFG")) {              // Displaying message            System.out.println("Element Inserted");        }        else {              // Displaying message            System.out.println("Element not Inserted");        }          // Displaying the Deque        System.out.println("ConcurrentLinkedDeque: "                           + cld);    }} |
Output:
ConcurrentLinkedDeque: [Welcome, To, Geeks, 4, Geeks] Element Inserted ConcurrentLinkedDeque: [Welcome, To, Geeks, 4, Geeks, GFG]
// Java Program to Demonstrate offer()// method of ConcurrentLinkedDeque  import java.util.concurrent.*;  class GFG {    public static void main(String[] args)    {          // Creating an empty Deque        ConcurrentLinkedDeque<String> cld            = new ConcurrentLinkedDeque<String>();          // Add elements into the Deque        cld.add("Welcome");        cld.add("To");        cld.add("Geeks");        cld.add("4");        cld.add("Geeks");          // Displaying the Deque        System.out.println("ConcurrentLinkedDeque: "                           + cld);          try {              // Insert null element using offer()            cld.offer(null);        }        catch (Exception e) {            System.out.println(e);        }    }} |
Output:
ConcurrentLinkedDeque: [Welcome, To, Geeks, 4, Geeks] java.lang.NullPointerException
Reference: https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/ConcurrentLinkedDeque.html#offer-E-
