ConcurrentLinkedQueue addAll() method in Java

The addAll() method of ConcurrentLinkedQueue is used to inserts all the elements of the Collection, passed as parameter to this method, at the end of a ConcurrentLinkedQueue. The insertion of element is in same order as returned by the collections iterator.

Syntax:

public boolean addAll(Collection<? extends E> c)

Parameter: This method takes a parameter cwhich represent collection whose elements are needed to be appended at the end of this ConcurrentLinkedQueue.

Returns: This method returns true if at least one action of insertion is performed.

Exception: This method throw two different Exceptions:



  • NullPointerException – if the passed collection or any of its elements are null.
  • IllegalArgumentException – if the passed collection is this queue itself.

Below programs illustrate addAll() method of ConcurrentLinkedQueue:

Example 1: Trying to add a list of numbers to ConcurrentLinkedQueue.

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// Java Program Demonstrate addAll()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<Integer>
            queue = new ConcurrentLinkedQueue<Integer>();
  
        // Add Numbers to queue
        queue.add(4353);
  
        // create a ArrayList of Numbers
        ArrayList<Integer> arraylist = new ArrayList<Integer>();
  
        // add some numbers to ArrayList
        arraylist.add(377139);
        arraylist.add(624378);
        arraylist.add(654793);
        arraylist.add(764764);
        arraylist.add(838494);
        arraylist.add(632845);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // Displaying the existing Collection
        System.out.println("Collection to be added: " + arraylist);
  
        // apply addAll() method and passed the arraylist as parameter
        boolean response = queue.addAll(arraylist);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("Collection added: " + response);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
    }
}

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Output:

ConcurrentLinkedQueue: [4353]
Collection to be added: [377139, 624378, 654793, 764764, 838494, 632845]
Collection added: true
ConcurrentLinkedQueue: [4353, 377139, 624378, 654793, 764764, 838494, 632845]

Example 2: Trying to add a list of Strings to ConcurrentLinkedQueue.

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// Java Program Demonstrate addAll()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<String>
            queue = new ConcurrentLinkedQueue<String>();
  
        // Add String to queue
        queue.add("Aman");
        queue.add("Amar");
  
        // create a ArrayList of Numbers
        ArrayList<String> arraylist = new ArrayList<String>();
  
        // add some numbers to ArrayList
  
        arraylist.add("Sanjeet");
        arraylist.add("Rabi");
        arraylist.add("Debasis");
        arraylist.add("Raunak");
        arraylist.add("Mahesh");
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // Displaying the existing Collection
        System.out.println("Collection to be added: " + arraylist);
  
        // apply addAll() method and passed the arraylist as parameter
        boolean response = queue.addAll(arraylist);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("Collection added: " + response);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
    }
}

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Output:

ConcurrentLinkedQueue: [Aman, Amar]
Collection to be added: [Sanjeet, Rabi, Debasis, Raunak, Mahesh]
Collection added: true
ConcurrentLinkedQueue: [Aman, Amar, Sanjeet, Rabi, Debasis, Raunak, Mahesh]

Example 3: Showing NullPointerException

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// Java Program Demonstrate addAll()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<String>
            queue = new ConcurrentLinkedQueue<String>();
  
        // Add String to queue
        queue.add("Aman");
        queue.add("Amar");
  
        // create a ArrayList which is equal to null
        ArrayList<String> arraylist = null;
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // Displaying the existing Collection
        System.out.println("Collection to be added: " + arraylist);
  
        try {
            // apply addAll() method and pass the arraylist as parameter
            // since the arraylist is null, exception will be thrown
            boolean response = queue.addAll(arraylist);
        }
        catch (NullPointerException e) {
            System.out.println("Exception thrown while adding null: " + e);
        }
    }
}

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Output:

ConcurrentLinkedQueue: [Aman, Amar]
Collection to be added: null
Exception thrown while adding null: java.lang.NullPointerException

Example 4: Showing IllegalArgumentException

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// Java Program Demonstrate addAll()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<String>
            queue = new ConcurrentLinkedQueue<String>();
  
        // Add String to queue
        queue.add("Aman");
        queue.add("Amar");
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        try {
            // apply addAll() method and passed the queue as parameter
            boolean response = queue.addAll(queue);
        }
        catch (IllegalArgumentException e) {
            System.out.println("Exception thrown while adding queue"
                               + " to itself when collection is required: " + e);
        }
    }
}

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Output:

ConcurrentLinkedQueue: [Aman, Amar]
Exception thrown 
 while adding queue to itself
 when collection is required: java.lang.IllegalArgumentException

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedQueue.html#addAll-java.util.Collection-

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