写一个普通的队列

package structures;

public interface Queue<E> {
    int getSize();
    E getFront();
    boolean isEmpty();
    void enqueue(E e);
    E dequeue();
}

package structures;

public class ArrayQueue<E> implements Queue<E> {

    private Array<E> array;

    public ArrayQueue(int capacity) {
        array = new Array<>(capacity);
    }

    public ArrayQueue() {
        this(10);
    }

    @Override
    public int getSize() {
        return array.getSize();
    }

    @Override
    public E getFront() {
        return array.getFirst();
    }

    @Override
    public boolean isEmpty() {
        return array.isEmpty();
    }

    @Override
    public void enqueue(E e) {
        array.addLast(e);
    }

    @Override
    public E dequeue() {
        return array.removeFirst();
    }

    public int getCapacity() {
        return array.getCapacity();
    }

    @Override
    public String toString() {
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("<queue> top[");

        for (int i = 0; i < array.getSize(); i++) {
            stringBuffer.append(array.get(i));
            if (i != array.getSize() - 1) {
                stringBuffer.append(",");
            }
        }

        stringBuffer.append("] <tail>\n");

        return stringBuffer.toString();
    }
}