Deque getFirst() method in Java Last Updated : 19 Sep, 2023 Comments Improve Suggest changes Like Article Like Report The getFirst() method of Deque Interface returns the first element or the head of the Deque. It does not deletes the element. It throws an exception when the Deque is empty. Syntax: E getFirst() Parameters: This method does not accepts any parameter.Returns: This method returns the first element or the head of the Deque but does not delete it.Exception: The function throws NoSuchElementException when the Deque is empty and the function is called. Below programs illustrate getFirst() method of Deque:Program 1: With the help of LinkedList. Java // Java Program Demonstrate getFirst() // method of Deque import java.util.*; public class GFG { public static void main(String[] args) throws IllegalStateException { // create object of Deque Deque<Integer> DQ = new LinkedList<Integer>(); // Add numbers to end of Deque DQ.add(7855642); DQ.add(35658786); DQ.add(5278367); DQ.add(74381793); // print Deque System.out.println("Deque: " + DQ); // print head System.out.println("Deque's head: " + DQ.getFirst()); } } Output: Deque: [7855642, 35658786, 5278367, 74381793] Deque's head: 7855642 Program 2: With the help of ArrayDeque. Java // Java Program Demonstrate getFirst() // method of Deque import java.util.*; public class GFG { public static void main(String[] args) throws IllegalStateException { // create object of Deque Deque<Integer> DQ = new ArrayDeque<Integer>(); // Add numbers to end of Deque DQ.add(7855642); DQ.add(35658786); DQ.add(5278367); DQ.add(74381793); // print Deque System.out.println("Deque: " + DQ); // print head System.out.println("Deque's head: " + DQ.getFirst()); } } Output: Deque: [7855642, 35658786, 5278367, 74381793] Deque's head: 7855642 Program 3: With the help of LinkedBlockingDeque. Java // Java Program Demonstrate getFirst() // method of Deque import java.util.*; import java.util.concurrent.LinkedBlockingDeque; public class GFG { public static void main(String[] args) throws IllegalStateException { // create object of Deque Deque<Integer> DQ = new LinkedBlockingDeque<Integer>(); // Add numbers to end of Deque DQ.add(7855642); DQ.add(35658786); DQ.add(5278367); DQ.add(74381793); // print Deque System.out.println("Deque: " + DQ); // print head System.out.println("Deque's head: " + DQ.getFirst()); } } Output: Deque: [7855642, 35658786, 5278367, 74381793] Deque's head: 7855642 Program 4: With the help of ConcurrentLinkedDeque. Java // Java Program Demonstrate getFirst() // method of Deque import java.util.*; import java.util.concurrent.ConcurrentLinkedDeque; public class GFG { public static void main(String[] args) throws IllegalStateException { // create object of Deque Deque<Integer> DQ = new ConcurrentLinkedDeque<Integer>(); // Add numbers to end of Deque DQ.add(7855642); DQ.add(35658786); DQ.add(5278367); DQ.add(74381793); // print Deque System.out.println("Deque: " + DQ); // print head System.out.println("Deque's head: " + DQ.getFirst()); } } Output: Deque: [7855642, 35658786, 5278367, 74381793] Deque's head: 7855642 Program 2: Java // Java Program Demonstrate getFirst() // method of Deque when it is empty import java.util.*; public class GFG { public static void main(String[] args) throws IllegalStateException { // create object of Deque Deque<Integer> DQ = new LinkedList<Integer>(); // Add numbers to end of Deque DQ.add(7855642); DQ.add(35658786); DQ.add(5278367); DQ.add(74381793); // print Deque System.out.println("Deque: " + DQ); // print head System.out.println("Deque's head: " + DQ.getFirst()); DQ.clear(); // Deque is empty now hence exception System.out.println("Deque's head: " + DQ.getFirst()); } } Output: Exception in thread "main" java.util.NoSuchElementException at java.util.LinkedList.getFirst(LinkedList.java:244) at GFG.main(GFG.java:29) Comment More infoAdvertise with us Next Article Deque getLast() method in Java G gopaldave Follow Improve Article Tags : Java Java - util package Java-Functions java-deque Practice Tags : Java Similar Reads Deque Interface in Java Deque Interface present in java.util package is a subtype of the queue interface. 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