Queues

Queues

Theory

• Abstract data type
• First in, first out (FIFO)
• Add: also called enqueue, add an item to the end of the queue
• remove: also called dequeue, remove the item at the front of the queue
• peek: get the item at the front of the queue, but don't remove it

Implementation (Array)

public static ArrayQueue{
    private Employee[] queue;
    private int front;
    private int back;

    public ArrayQueue(int capacity) {
        queue = new Employee[capacity];
    }

    public void add(Employee employee) {
        if (back == queue.length) {
            Employee[] newArray = new Employee[2 * queue.length];
            System.arraycopy(queue, 0, newArray, queue.length);
            queue = newArray;
        }

        queue[back] = employee;
        back++;
    }
}

Queues and the JDK

[Challenge] Queue