Queue remove() method in Java
Last Updated :
18 Aug, 2022
The remove() method of Queue Interface returns and removes the element at the front of the container. It deletes the head of the container. The method throws an NoSuchElementException when the Queue is empty.
Syntax:
E remove()
Returns: This method returns the head of the Queue.
Exception: The function throws an NoSuchElementException when the Queue is empty.
Below programs illustrate remove() method of Queue:
Program 1: With the help of LinkedList.
Java
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
Queue<Integer> Q
= new LinkedList<Integer>();
Q.add( 7855642 );
Q.add( 35658786 );
Q.add( 5278367 );
Q.add( 74381793 );
System.out.println("Queue: " + Q);
System.out.println("Queue's head: " + Q.remove());
System.out.println("Queue's head: " + Q.remove());
}
}
|
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Program 2: With the help of ArrayDeque.
Java
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
Queue<Integer> Q
= new ArrayDeque<Integer>();
Q.add( 7855642 );
Q.add( 35658786 );
Q.add( 5278367 );
Q.add( 74381793 );
System.out.println("Queue: " + Q);
System.out.println("Queue's head: " + Q.remove());
System.out.println("Queue's head: " + Q.remove());
}
}
|
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Program 3: With the help of LinkedBlockingDeque.
Java
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
Queue<Integer> Q
= new LinkedBlockingDeque<Integer>();
Q.add( 7855642 );
Q.add( 35658786 );
Q.add( 5278367 );
Q.add( 74381793 );
System.out.println("Queue: " + Q);
System.out.println("Queue's head: " + Q.remove());
System.out.println("Queue's head: " + Q.remove());
}
}
|
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Program 4: With the help of ConcurrentLinkedDeque.
Java
import java.util.*;
import java.util.concurrent.ConcurrentLinkedDeque;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
Queue<Integer> Q
= new ConcurrentLinkedDeque<Integer>();
Q.add( 7855642 );
Q.add( 35658786 );
Q.add( 5278367 );
Q.add( 74381793 );
System.out.println("Queue: " + Q);
System.out.println("Queue's head: " + Q.remove());
System.out.println("Queue's head: " + Q.remove());
}
}
|
Output:
Queue: [7855642, 35658786, 5278367, 74381793]
Queue's head: 7855642
Queue's head: 35658786
Below programs illustrate exceptions thrown by this method: Program 5: To show NoSuchElementException.
Java
import java.util.*;
public class GFG {
public static void main(String[] args)
throws IllegalStateException
{
Queue<Integer> Q
= new LinkedList<Integer>();
Q.add( 423 );
Q.add( 3432 );
System.out.println("Queue: " + Q);
System.out.println("Queue's head: " + Q.remove());
System.out.println("Queue's head: " + Q.remove());
System.out.println("Queue: " + Q);
try {
System.out.println("Queue's head: " + Q.element());
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
|
Output:
Queue: [423, 3432]
Queue's head: 423
Queue's head: 3432
Queue: []
Exception: java.util.NoSuchElementException
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/Queue.html#remove–