Java ArrayDeque Class: peekFirst() Method

public E peekFirst()

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

Package: java.util

Java Platform: Java SE 8

Syntax:

peekFirst()

Return Value:

the head of this deque, or null if this deque is empty

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

Pictorial Presentation

Example: Java ArrayDeque Class: peekFirst() Method

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

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

      // Use add() method to add elements in the deque
      deque.add(20);
      deque.add(30);
      deque.add(40);
      deque.add(35);        
      
      // Print all the elements of the original deque
      System.out.println("Elements of the original deque:");
      for (Integer n : deque) {
         System.out.println(n);
      }

  // Retrieve head of the queue
      int val = deque.peekFirst();
      System.out.println("Retrieved Element is " + val);

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

Output:

Elements of the original deque:
20
30
40
35
Retrieved Element is 20
Elements of the deque:
20
30
40
35

Java Code Editor:

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