The java.util.concurrent.ConcurrentLinkedDeque.getFirst() method is an in-built method in Java which returns the first element of the deque container.
Syntax:
Conn_Linked_Deque.getFirst()
Parameters: The method does not accept any parameter.
Return Value: The method returns the first element present in the Deque.
Exception: The function throws a NoSuchElementException when the deque is empty.
Below programs illustrate the ConcurrentLinkedDeque.getFirst() method :
Program 1:
/* Java Program to Demonstrate getFirst() 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("Elements in the Deque: " + cld); // Displaying the first element System.out.println("The first element is: " + cld.getFirst()); }} |
Output:
Elements in the Deque: [Welcome, To, Geeks, 4, Geeks] The first element is: Welcome
Program 2:
/* Java Program to Demonstrate getFirst() method of ConcurrentLinkedDeque */ import java.util.concurrent.*;class GFG { public static void main(String[] args) { // Creating an empty Deque ConcurrentLinkedDeque<Integer> cld = new ConcurrentLinkedDeque<Integer>(); try { // Displaying the first element System.out.println("The first element " + "is: " + cld.getFirst()); } catch (Exception e) { System.out.println(e); } // Add elements into the Deque cld.add(12); cld.add(43); cld.add(29); cld.add(16); cld.add(70); // Displaying the Deque System.out.println("Elements in the Deque: " + cld); // Displaying the first element System.out.println("The first element is: " + cld.getFirst()); }} |
Output:
java.util.NoSuchElementException Elements in the Deque: [12, 43, 29, 16, 70] The first element is: 12
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedDeque.html#getFirst()
