[队列] 数组实现的队列

上代码

public class Queue<E> {

    // 元素
    private Object[] elements;

    // 队列的容量
    private int size = 0;

    // 每次扩容的增量
    private final int addCapacity = 10;

    public Queue() {
        elements = new Object[10];
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public E peek() {
        if(isEmpty()) {
            return null;
        }
        return (E)elements[0];

    }

    public E pop() {
        if(isEmpty()) {
            return null;
        }
        E out = (E)elements[0];
        for(int i = 0; i < size - 1; i++) {
            elements[i] = elements[i + 1];
        }
        size--;
        return out;
    }

    public void push(E data) {
        ensureCapacity();
        elements[size++] = data;
    }

    private void ensureCapacity() {
        if(size >= elements.length) {
            elements = Arrays.copyOf(elements, size + addCapacity);
        }
    }

    public static void main(String[] args) {
        Queue<Integer> queue = new Queue<>();
        for(int i = 1; i < 15; i++) {
            queue.push(i);
        }
        while (queue.peek() != null) {
            System.out.println(queue.pop());
        }
    }
}

控制面板打印

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