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LinkedBlockingDeque offerFirst() method in Java
  • Last Updated : 20 Nov, 2020

The offerFirst(E e) method of LinkedBlockingDeque inserts the element passed in the parameter at the front of the Deque container. If the container’s capacity has exceeded, then it does not returns an exception as in case of add() and addFirst() function.

Syntax:  

public boolean offerFirst(E e)

Parameters: This method accepts a mandatory parameter e which is the element to be inserted at the front of the LinkedBlockingDeque. 

Returns: This method returns true if the element has been inserted, else it returns false. 

Below programs illustrate offerFirst() method of LinkedBlockingDeque:



Program 1:  

Java




// Java Program Demonstrate offerFirst()
// method of LinkedBlockingDeque
 
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
 
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
 
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>(4);
 
        // Add numbers to end of LinkedBlockingDeque
        LBD.offerFirst(7855642);
        LBD.offerFirst(35658786);
        LBD.offerFirst(5278367);
        LBD.offerFirst(74381793);
 
        // Cannot be inserted
        LBD.offerFirst(10);
 
        // cannot be inserted hence returns false
        if (!LBD.offerFirst(10))
            System.out.println("The element 10 cannot be inserted"+
                                           " as capacity is full");
 
        // before removing print queue
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}
Output: 
The element 10 cannot be inserted as capacity is full
Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642]




 

Program 2: 

Java




// Java Program Demonstrate offerFirst()
// method of LinkedBlockingDeque
 
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
 
public class GFG {
    public static void main(String[] args)
        throws IllegalStateException
    {
 
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<String> LBD
            = new LinkedBlockingDeque<String>(4);
 
        // Add numbers to end of LinkedBlockingDeque
        LBD.offerFirst("abc");
        LBD.offerFirst("gopu");
        LBD.offerFirst("geeks");
        LBD.offerFirst("richik");
 
        // Cannot be inserted
        LBD.offerFirst("hii");
 
        // cannot be inserted hence returns false
        if (!LBD.offerFirst("hii"))
            System.out.println("The element 'hii' cannot be"
                           +" inserted as capacity is full");
 
        // before removing print queue
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}
Output: 
The element 'hii' cannot be inserted as capacity is full
Linked Blocking Deque: [richik, geeks, gopu, abc]




 

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#offerFirst(E)
 

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