The removeFirst() method of LinkedBlockingDeque returns and removes the first element of the Deque container from it. The method throws an NoSuchElementException if the Deque container is empty.
Syntax:
public E removeFirst()
Returns: This method returns the head of the Deque container, which is the first element.
Exception: The function throws a NoSuchElementException if the Deque is empty.
Below programs illustrate removeFirst() method of LinkedBlockingDeque:
Program 1:
// Java Program to demonstrate removeFirst() // method of LinkedBlockingDeque import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Integer> LBD
= new LinkedBlockingDeque<Integer>();
// Add numbers to end of LinkedBlockingDeque
LBD.add( 7855642 );
LBD.add( 35658786 );
LBD.add( 5278367 );
LBD.add( 74381793 );
// print Dequee
System.out.println( "Linked Blocking Deque: " + LBD);
// removes the front element and prints it
System.out.println( "First element of Linked Blocking Deque: "
+ LBD.removeFirst());
// prints the Deque
System.out.println( "Linked Blocking Deque: " + LBD);
}
} |
Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793] First element of Linked Blocking Deque: 7855642 Linked Blocking Deque: [35658786, 5278367, 74381793]
Program 2:
// Java Program to demonstrate removeFirst() // method of LinkedBlockingDeque import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws NoSuchElementException
{
// create object of LinkedBlockingDeque
LinkedBlockingDeque<Integer> LBD
= new LinkedBlockingDeque<Integer>();
// print Dequee
System.out.println( "Linked Blocking Deque: " + LBD);
try {
// throws an exception
LBD.removeFirst();
}
catch (Exception e) {
System.out.println( "Exception when removing "
+ "first element from this Deque: "
+ e);
}
}
} |
Linked Blocking Deque: [] Exception when removing first element from this Deque: java.util.NoSuchElementException
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingDeque.html#removeFirst–