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BlockingDeque peek() method in Java with examples

Last Updated : 01 Oct, 2019
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The peek() method of BlockingDeque returns the front element in the Deque container. It returns null if the container is empty.

Syntax:

public E peek()

Parameters: This method does not accept any parameters.

Returns: This method returns front element in the Deque container if the container is not empty. It returns false if the container is empty.

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

Below programs illustrate peek() method of BlockingDeque:

Program 1:




// Java Program Demonstrate peek()
// 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)
  
    {
  
        // 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);
  
        // Print the queue
        System.out.println("Linked Blocking Deque: " + BD);
  
        System.out.println("Front element in Deque: " + BD.peek());
    }
}


Output:

Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]
Front element in Deque: 7855642

Program 2:




// Java Program Demonstrate peek()
// method of BlockingDeque
// when Deque is empty
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.BlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
  
    {
  
        // 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);
  
        // Print the queue
        System.out.println("Blocking Deque: " + BD);
  
        // empty deque
        BD.clear();
  
        System.out.println("Front element in Deque: " + BD.peek());
    }
}


Output:

Blocking Deque: [7855642, 35658786, 5278367, 74381793]
Front element in Deque: null

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingDeque.html#peek()



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