The contains(Object o) method of BlockingQueue interface checks if the passed element in the parameter exists in the container or not. It returns true if the element exists in the container else it returns a false value.
Syntax:
public boolean contains(Object o)
Parameters: This method accepts a mandatory parameter o whose presence in the container is to be checked in the container.
Returns: This method returns true if the element is present, else it returns false.
Note: The contains() method of BlockingQueue has been inherited from the Queue class in Java.
Below programs illustrate contains() method of BlockingQueue:
Program 1:
// Java Program Demonstrate contains()// method of BlockingQueue  import java.util.concurrent.LinkedBlockingQueue;import java.util.concurrent.BlockingQueue;import java.util.*;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of BlockingQueue        BlockingQueue<Integer> BQ            = new LinkedBlockingQueue<Integer>();          // Add numbers to end of BlockingQueue        BQ.add(10);        BQ.add(20);        BQ.add(30);        BQ.add(40);          // before removing print queue        System.out.println("Blocking Queue: " + BQ);          // check for presence using function        if (BQ.contains(10)) {            System.out.println("Blocking Queue contains 10");        }        else {            System.out.println("Blocking Queue does not contain 10");        }    }} |
Output:
Blocking Queue: [10, 20, 30, 40] Blocking Queue contains 10
Program 2:
// Java Program Demonstrate contains()// method of BlockingQueue  import java.util.concurrent.LinkedBlockingQueue;import java.util.concurrent.BlockingQueue;import java.util.*;  public class GFG {    public static void main(String[] args)        throws IllegalStateException    {          // create object of BlockingQueue        BlockingQueue<String> BQ            = new LinkedBlockingQueue<String>();          // Add numbers to end of BlockingQueue        BQ.add("ab");        BQ.add("cd");        BQ.add("fg");        BQ.add("xz");          // before removing print queue        System.out.println("Blocking Queue: " + BQ);          // check for presence using function        if (BQ.contains("go")) {            System.out.println("Blocking Queue contains 'go'");        }        else {            System.out.println("Blocking Queue does not contain 'go'");        }    }} |
Output:
Blocking Queue: [ab, cd, fg, xz] Blocking Queue does not contain 'go'
