BlockingDeque add() method in Java with Examples

The add(E e) method of BlockingDeque inserts the element passed in the parameter to the end of the Deque is there is space. If the BlockingDeque 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 BlockingDeque.

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

Note: The add() method of BlockingDeque has been inherited from the LinkedBlockingDeque class in Java.

Below programs illustrate add() method of Deque:

Program 1:

// Java Program Demonstrate add()
// method of BlockingDeque

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

public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {

        // create object of BlockingDeque
        BlockingDeque<Integer> BD
            = new LinkedBlockingDeque<Integer>();

        // Add numbers to end of BlockingDeque
        BD.add(7855642);
        BD.add(35658786);
        BD.add(5278367);
        BD.add(74381793);

        // before removing print queue
        System.out.println("Blocking Deque: " + BD);
    }
}

Output:

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

Program 2:

// Java Program Demonstrate add()
// method of BlockingDeque
// when it is Full
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {

        // create object of BlockingDeque
        // size of list
        BlockingDeque<Integer> BD
            = new LinkedBlockingDeque<Integer>(3);

        // Add numbers to end of BlockingDeque
        BD.add(7855642);
        BD.add(35658786);
        BD.add(5278367);

        // it is full
        BD.add(74381793);

        // before removing print Deque
        System.out.println("Blocking Deque: " + BD);
    }
}

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:24)

Program 3:

// Java Program Demonstrate add()
// method of BlockingDeque
// when null is inserted

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

public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {

        // create object of BlockingDeque
        BlockingDeque<Integer> BD
            = new LinkedBlockingDeque<Integer>();

        // Add numbers to end of BlockingDeque
        BD.add(7855642);
        BD.add(35658786);
        BD.add(5278367);

        // NULL
        BD.add(null);

        // before removing print Deque
        System.out.println("Blocking Deque: " + BD);
    }
}

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/BlockingDeque.html#add(E)