ArrayBlockingQueue contains() method in Java

Last Updated : 26 Nov, 2018

ArrayBlockingQueue is bounded, blocking queue that stores the elements internally backed by an array.

ArrayBlockingQueue class is a member of the Java Collections Framework.
Bounded means it will have a fixed size, you can not store number the elements more than the capacity of the queue.
The queue also follows FIFO (first-in-first-out) rule for storing and removing elements from the queue.
If you try to put an element into a full queue or to take an element from an empty queue then the queue will block you.

The contains(Object o) method returns true if queue contains the object o passed as parameter. We can say that method returns true if and only if this queue contains at least one element e which is equal to object o passed as parameter i.e. o.equals(e).
Syntax:

public boolean contains(Object o)

Parameter:
o – object to check whether queue contains the specified object.
Return Value:
true if this queue contains the object

Below program illustrate contains method of ArrayBlockingQueue.
Example 1

   // Java Program Demonstrate contains(Object o) 
// method of ArrayBlockingQueue. 
  
import java.util.concurrent.ArrayBlockingQueue; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
        // define capacity of ArrayBlockingQueue 
        int capacity = 5; 
  
        // create object of ArrayBlockingQueue 
        ArrayBlockingQueue<Integer> queue 
            = new ArrayBlockingQueue<Integer>(capacity); 
  
        // Add elements to ArrayBlockingQueue 
        queue.add(23); 
        queue.add(32); 
        queue.add(45); 
        queue.add(12); 
  
        // check whether queue contains 23 
        boolean response1 = queue.contains(23); 
  
        // print after applying contains method with 23 as parameter 
        System.out.println("queue contains 23 : " + response1); 
  
        // check whether queue contains 99 
        boolean response2 = queue.contains(99); 
  
        // print after applying contains method with 99 as parameter 
        System.out.println("queue contains 99 : " + response2); 
    } 
} 
 
  

Output:

  queue contains 23 : true  queue contains 99 : false

Example 2

   // Java Program Demonstrate contains(Object o) 
// method of ArrayBlockingQueue. 
import java.util.concurrent.ArrayBlockingQueue; 
  
public class GFG { 
  
    // create a User Object with name and age as attribute 
    public class User { 
  
        public String name; 
        public String age; 
        User(String name, String age) 
        { 
            this.name = name; 
            this.age = age; 
        } 
    } 
  
    // Main Method 
    public static void main(String[] args) 
    { 
        GFG gfg = new GFG(); 
        gfg.containsMethodExample(); 
    } 
  
    // Method to give example of contains function 
    public void containsMethodExample() 
    { 
  
        // define capacity of ArrayBlockingQueue 
        int capacity = 5; 
  
        // create object of ArrayBlockingQueue 
        ArrayBlockingQueue<User> queue 
            = new ArrayBlockingQueue<User>(capacity); 
  
        User user1 = new User("Aman", "24"); 
        User user2 = new User("Amar", "23"); 
        User user3 = new User("Sanjeet", "25"); 
        User user4 = new User("Suvo", "26"); 
  
        // Add Objects to ArrayBlockingQueue 
        queue.add(user1); 
        queue.add(user2); 
        queue.add(user3); 
        queue.add(user4); 
  
        User user5 = new User("Ravi", "22"); 
        // check whether queue contains User1 
        boolean response1 = queue.contains(user1); 
  
        // print after applying contains method with user1 as parameter 
        System.out.println("queue contains User having name "
                           + user1.name + " : " + response1); 
  
        // check whether queue contains User5 
        boolean response2 = queue.contains(user5); 
  
        // print after applying contains method with user1 as parameter 
        System.out.println("queue contains User having name "
                           + user5.name + " : " + response2); 
    } 
} 
 
  

Output:

  queue contains User having name Aman : true  queue contains User having name Ravi : false

Reference:
https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ArrayBlockingQueue.html#contains(java.lang.Object)

ArrayBlockingQueue drainTo() Method in Java

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