自己实现数据结构---Queue

public interface Queue<E> {

    void enqueue(E e);
    E dequeue();
    E getFront();
    int getSize();
    boolean isEmpty();

}

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

    private ArrayList<E> arrayList;
    public ArrayQueue(int capacity){
        arrayList = new ArrayList<>(capacity);
    }
    public ArrayQueue(){
        arrayList = new ArrayList<>();
    }

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

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

    @Override
    public E getFront() {
        return arrayList.get(0);
    }

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

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


}