Java.util.ArrayDeque Class in Java | Set 2

Difficulty Level : Easy
Last Updated : 25 Nov, 2019

Java.util.ArrayDeque Class in Java | Set 1
More Methods of util.ArrayDeque Class :

offer(Element e) : java.util.ArrayDeque.offer(Element e) : inserts element at the end of deque.
Syntax :

public boolean offer(Element e)
Parameters : 
e - element to add
Return : 
true, if element is added else; false

offerFirst(Element e) : java.util.ArrayDeque.offerFirst(Element e) : inserts element at the front of deque.
Syntax :

public boolean offerFirst(Element e)
Parameters : 
e - element to add
Return : 
true, if element is added else; false

offerLast(Element e) : java.util.ArrayDeque.offerLast(Element e) : inserts element at the end of deque.
Syntax :

public boolean offerLast(Element e)
Parameters : 
e - element to add
Return : 
true, if element is added else; false

peek() : java.util.ArrayDeque.peek(): returns head element without removing it.
Syntax :

public E peek()
Parameters :
--------
Return : 
head of deque or null if deque is empty.

peekFirst() : java.util.ArrayDeque.peekFirst() :returns first element without removing it.
Syntax :

public E peekFirst()
Parameters :
--------
Return : 
first element of deque or null if deque is empty.

peekLast() : java.util.ArrayDeque.peek(): returns last element without removing it.
Syntax :

public E peekLast()
Parameters :
--------
Return : 
Last element of deque or null if deque is empty.

poll() : java.util.ArrayDeque.peek(): returns head element and also removes it
Syntax :

public E poll()
Parameters :
--------
Return : 
head of deque or null if deque is empty.

pollFirst() : java.util.ArrayDeque.peek(): returns first element and also removes it
Syntax :

public E pollFirst()
Parameters :
--------
Return : 
first element of deque or null if deque is empty.

pollLast() : java.util.ArrayDeque.peek(): returns last element and also removes it
Syntax :

public E pollLast()
Parameters :
--------
Return : 
last element of deque or null if deque is empty.

pop() : java.util.ArrayDeque.pop() : pops out an element for stack repesentyed by deque
Syntax :
```
public E pop()
Parameters :
---------
Return : 
element at front
```
push(Element e) : java.util.ArrayDeque.push(Element e) : pushes an element onto stack repesentyed by deque
Syntax :
```
public void push(Element e)
Parameters :
e : element to be pushed
Return : 
----------
```
remove() : java.util.ArrayDeque.remove(): returns head element and also removes it
Syntax :
```
public E remove()
Parameters :
------
Return : 
head of the deque
```
removeFirst() : java.util.ArrayDeque.remove(): returns first element and also removes it
Syntax :
```
public E removeFirst()
Parameters :
------
Return : 
first element of the deque
```
removeLast() : java.util.ArrayDeque.remove(): returns last element and also removes it
Syntax :
```
public E removeLast()
Parameters :
------
Return : 
last element of the deque
```

removeFirstOccurrence(Obj) : java.util.ArrayDeque.removeFirstOccurrence(Obj) : removes the element where it first occur in the deque.
Syntax :

public boolean removeFirstOccurrence(Object obj)
Parameters :
obj : element to be removed
Return : 
true, if the element is removed; else False

removeLastOccurrence(Obj) : java.util.ArrayDeque.removeLastOccurrence(Obj) : removes the element where it last occur in the deque.
Syntax :

public boolean removeLastOccurrence(Object obj)
Parameters :
obj : element to be removed
Return : 
true, if the element is removed; else False

Java Program explaining util.ArrayDeque class methods :

// Java code explaining the use of ArrayDeque class methods
// offer(), offerFirst(), offerLast(), peek(), peekFirst(), peekLast()
// poll(), peekFirst(), peekLast(), pop(), push()
  
import java.util.*;
public class NewClass
{
    public static void main(String[] args)
    {
        // Intializing an deque
        Deque<Integer> d = new ArrayDeque<Integer>(10);
  
        // add() method to insert
        d.add(2);
        d.add(4);
  
        // offer() : add element at end
        d.offer(100);
        d.offer(101);
  
        // offerFirst() : add element at start
        d.offerFirst(1111);
        d.offerFirst(3333);
  
        // offerLast() : add element at end
        d.offerLast(5000);
        d.offerLast(50001);
  
        for (Integer element : d)
        {
            System.out.println("Element : " + element);
        }
  
        // peek() method : to get head
        System.out.println("\nHead element : " + d.peek());
  
        // peekFirst() method : to get First element
        System.out.println("First element : " + d.peekFirst());
  
        // peekLast() method : to get Last element
        System.out.println("Last element : " + d.peekLast());
  
  
        // poll() method : to get head
        System.out.println("\nHead element poll : " + d.poll());
  
        // pollFirst() method : to get First element
        System.out.println("First element poll : " + d.pollFirst());
  
        // pollLast() method : to get Last element
        System.out.println("Last element poll : " + d.pollLast() + "\n");
  
        for (Integer element : d)
        {
            System.out.println("Element : " + element);
        }
  
        // pop() method :
        System.out.println("Pop element : " + d.pop());
  
        // push() method :
        d.push(11010101);
        d.push(121212121);
        d.push(131313131);
  
        // remove() method : to get head
        System.out.println("\nHead element remove : " + d.remove());
  
        // removeFirst() method : to get First element
        System.out.println("First element remove : " + d.removeFirst());
  
        // removeLast() method : to get Last element
        System.out.println("Last element remove : " + d.removeLast() + "\n");
  
        for (Integer element : d)
        {
            System.out.println("Element : " + element);
        }
  
    }
}

Output :

Element : 3333
Element : 1111
Element : 2
Element : 4
Element : 100
Element : 101
Element : 5000
Element : 50001

Head element : 3333
First element : 3333
Last element : 50001

Head element poll : 3333
First element poll : 1111
Last element poll : 50001

Element : 2
Element : 4
Element : 100
Element : 101
Element : 5000
Pop element : 2

Head element remove : 131313131
First element remove : 121212121
Last element remove : 5000

Element : 11010101
Element : 4
Element : 100
Element : 101

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