add : Inserts the element into the queue

boolean add(E e)

Inserts the specified element into the queue. return true upon success and throwing an IllegalStateException if no space is currently available (capacity-restricted deque). This method is equivalent to addLast.

import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;

class DequeAdd{
 public static void main(String args[]){
  Deque<Integer> myDeque = new LinkedBlockingDeque<Integer> (4);
  
  System.out.println("Is 10 added to the Deque " + myDeque.add(10));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 20 added to the Deque " + myDeque.add(20));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 30 added to the Deque " + myDeque.add(30));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 40 added to the Deque " + myDeque.add(40));
  System.out.println("Elements in Deque are " + myDeque);
  
 }
}

 

Output

Is 10 added to the Deque true
Elements in Deque are [10]

Is 20 added to the Deque true
Elements in Deque are [10, 20]

Is 30 added to the Deque true
Elements in Deque are [10, 20, 30]

Is 40 added to the Deque true
Elements in Deque are [10, 20, 30, 40]

1. throws IllegalStateException if the element cannot be added at this

time due to capacity restrictions

import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;

class DequeAddIllegal{
 public static void main(String args[]){
  Deque<Integer> myDeque = new LinkedBlockingDeque<Integer> (4);
  
  System.out.println("Is 10 added to the Deque " + myDeque.add(10));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 20 added to the Deque " + myDeque.add(20));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 30 added to the Deque " + myDeque.add(30));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 40 added to the Deque " + myDeque.add(40));
  System.out.println("Elements in Deque are " + myDeque);
  
  System.out.println("\nIs 50 added to the Deque " + myDeque.add(50));
  System.out.println("Elements in Deque are " + myDeque);
  
 }
}

Output

Is 10 added to the Deque true
Elements in Deque are [10]

Is 20 added to the Deque true
Elements in Deque are [10, 20]

Is 30 added to the Deque true
Elements in Deque are [10, 20, 30]

Is 40 added to the Deque true
Elements in Deque are [10, 20, 30, 40]
Exception in thread "main" java.lang.IllegalStateException: Deque full
        at java.util.concurrent.LinkedBlockingDeque.addLast(LinkedBlockingDeque.java:332)
        at java.util.concurrent.LinkedBlockingDeque.add(LinkedBlockingDeque.java:631)
        at DequeAddIllegal.main(DequeAddIllegal.java:20)

2. throws ClassCastException if the class of the specified element

prevents it from being added to this deque

3. throws NullPointerException if the specified element is null and this

deque does not permit null elements

import java.util.*;
import java.util.concurrent.ConcurrentLinkedDeque;

class DequeAddNull{
 public static void main(String args[]){
  Deque<Integer> myDeque = new ConcurrentLinkedDeque<Integer> ();
  
  System.out.println("\nAdd null to the Deque");
  myDeque.add(null);
  System.out.println("Elements in Deque are\n" + myDeque);
 }
}

Output

Add null to the Deque
Exception in thread "main" java.lang.NullPointerException
        at java.util.concurrent.ConcurrentLinkedDeque.checkNotNull(ConcurrentLinkedDeque.java:800)
        at java.util.concurrent.ConcurrentLinkedDeque.linkLast(ConcurrentLinkedDeque.java:388)
        at java.util.concurrent.ConcurrentLinkedDeque.offerLast(ConcurrentLinkedDeque.java:930)
        at java.util.concurrent.ConcurrentLinkedDeque.add(ConcurrentLinkedDeque.java:1024)
        at DequeAddNull.main(DequeAddNull.java:9)

 

4. throws IllegalArgumentException if some property of the specified

element prevents it from being added to this deque

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