LinkedBlockingDeque add() method in Java

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The add(E e) method of LinkedBlockingDeque inserts the element passed in the parameter to the end of the Deque is there is space. If the LinkedBlockingDeque is capacity restricted and no space is left for insertion, it returns an IllegalStateException. It works exactly in the same way as addLast() method does.

Syntax:

public void add(E e)

Parameters: This method accepts a mandatory parameter e which is the element to be inserted in the end of the LinkedBlockingDeque.

Returns: This method does not returns anything.

Exception:

IllegalStateException: if the element cannot be added at this time due to capacity restrictions
NullPointerException: if the specified element is null

Below programs illustrate add() method of LinkedBlockingDeque:

Program 1:

// Java Program Demonstrate add()
// method of LinkedBlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
  
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
        LBD.add(74381793);
  
        // before removing print queue
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}

Output:

Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]

Program 2:

// Java Program Demonstrate add()
// method of LinkedBlockingDeque
// when it is Full
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
  
        // create object of LinkedBlockingDeque
        // size of list
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>(3);
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
  
        // it is full
        LBD.add(74381793);
  
        // before removing print queue
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}

Output:

Exception in thread "main" java.lang.IllegalStateException: Deque full
    at java.util.concurrent.LinkedBlockingDeque.addLast(LinkedBlockingDeque.java:335)
    at java.util.concurrent.LinkedBlockingDeque.add(LinkedBlockingDeque.java:633)
    at GFG.main(GFG.java:23)

Program 3:

// Java Program Demonstrate add()
// method of LinkedBlockingDeque
// when null is inserted
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
  
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
  
        // NULL
        LBD.add(null);
  
        // before removing print queue
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException
    at java.util.concurrent.LinkedBlockingDeque.offerLast(LinkedBlockingDeque.java:357)
    at java.util.concurrent.LinkedBlockingDeque.addLast(LinkedBlockingDeque.java:334)
    at java.util.concurrent.LinkedBlockingDeque.add(LinkedBlockingDeque.java:633)
    at GFG.main(GFG.java:23)

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#add(E)