Queues
The Queue
interface provides a way to store elements in a FIFO (First In, First Out) order. This tutorial will teach you how to use queues in Java.
Creating a Queue
To create a queue, use the LinkedList
class:
import java.util.LinkedList;
import java.util.Queue;
public class Main {
public static void main(String[] args) {
Queue queue = new LinkedList<>();
queue.add("Alice");
queue.add("Bob");
queue.add("Charlie");
System.out.println(queue);
}
}
Accessing Elements in a Queue
You can access elements in a queue using the peek
method:
public class Main {
public static void main(String[] args) {
Queue queue = new LinkedList<>();
queue.add("Alice");
queue.add("Bob");
queue.add("Charlie");
System.out.println(queue.peek()); // Outputs: Alice
}
}
Removing Elements from a Queue
Use the poll
method to remove elements from a queue:
public class Main {
public static void main(String[] args) {
Queue queue = new LinkedList<>();
queue.add("Alice");
queue.add("Bob");
queue.add("Charlie");
System.out.println(queue.poll()); // Outputs: Alice
System.out.println(queue); // Outputs: [Bob, Charlie]
}
}
Iterating Over a Queue
You can iterate over a queue using a for-each loop:
public class Main {
public static void main(String[] args) {
Queue queue = new LinkedList<>();
queue.add("Alice");
queue.add("Bob");
queue.add("Charlie");
for (String name : queue) {
System.out.println(name);
}
}
}
Continue exploring our intermediate tutorials to learn more about Java programming.