Java ArrayDeque Class: getFirst() Method

public E getFirst()

The getFirst() method is used to retrieve the first element of a given deque.

This method differs from peekFirst only in that it throws an exception if this deque is empty.

Package: java.util

Java Platform: Java SE 8

Syntax:

getFirst()

Return Value:

the head of this deque

Return Value Type: E - the type of elements held in this collection

Throws:

NoSuchElementException - if this deque is empty

Pictorial Presentation

Example: Java ArrayDeque Class: getFirst() Method

import java.util.ArrayDeque;
import java.util.Deque;

public class Main {
   public static void main(String[] args) {
   
   // Create an empty array deque with an initial capacity
      Deque<Integer> deque = new ArrayDeque(8);

      // Use add() method to add elements in the deque
      deque.add(10);
      deque.add(20);
      deque.add(30);
      deque.add(40);        

      // Print all the elements of the original deque
      System.out.println("Original elements of the deque: ");
      for (Integer n : deque) {
         System.out.println(n);
      }

      // Retrieve the first element of the deque.
      int e = deque.getFirst();
      System.out.println("Retrieve the first element: " + e);
   }
}
 

Output:

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Original elements of the deque: 
10
20
30
40
Retrieve the first element: 10

Java Code Editor:

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