PeekFirst() Method : Java.util.ArrayDeque

Declaration :

public E peekFirst()

1	public E peekFirst()

Explanation :

Purpose	The java.util.ArrayDeque.peekFirst() method retrieves the first element of this deque (but does not remove) .Returns null if this deque is empty.
Parameters	NA
Return Value	This method returns the head of this deque or null if this deque is empty.
Exception	NA

Java Program : Example

Below example will explain java.util.ArrayDeque.peekFirst() method.

package com.c4learn;
import java.util.ArrayDeque;
import java.util.Deque;
public class ArrayDequeDemo {
   public static void main(String[] args) {
      // Create empty array deque with an initial capacity
      Deque<Integer> deque = new ArrayDeque<Integer>(8);
      // Use add() method to add elements
      deque.add(100);
      deque.add(25);
      deque.add(54);
      deque.add(40);        
      deque.add(80);        
      int val = deque.peekFirst();
      System.out.println("Retrieved Element is " + val);
      // Print all the elements in deque after using peekFirst()
      for (Integer number : deque) {
         System.out.println("Element is " + number);
      }
   }
}

package com.c4learn;

import java.util.ArrayDeque;

import java.util.Deque;

public class ArrayDequeDemo {

public static void main(String[] args) {

// Create empty array deque with an initial capacity

Deque<Integer> deque = new ArrayDeque<Integer>(8);

// Use add() method to add elements

deque.add(100);

deque.add(25);

deque.add(54);

deque.add(40);

deque.add(80);

int val = deque.peekFirst();

System.out.println("Retrieved Element is " + val);

// Print all the elements in deque after using peekFirst()

for (Integer number : deque) {

System.out.println("Element is " + number);

}

Output of Program :

Retrieved Element is 100
Element is 100
Element is 25
Element is 54
Element is 40
Element is 80

Retrieved Element is 100

Element is 100

Element is 25

Element is 54

Element is 40

Element is 80