ArrayQueue数据结构(jdk8)

队列结构，源码分析

    public ArrayQueue(int capacity) {
        //容量
        this.capacity = capacity + 1;
        //队列
        this.queue = newArray(capacity + 1);
        //头指针
        this.head = 0;
        //尾指针
        this.tail = 0;
    }

    public boolean add(T o) {
        //加到队尾
        queue[tail] = o;
        //为0 代表和容量一样大小，满了
        int newtail = (tail + 1) % capacity;
        if (newtail == head)
            throw new IndexOutOfBoundsException("Queue full");
        //新的尾指针
        tail = newtail;
        return true; // we did add something
    }
    
    //改变队列大小
    public void resize(int newcapacity) {
        // 保存数据的个数
        int size = size();
        //如果新的size比数据量小，就要丢数据，抛出异常
        if (newcapacity < size)
            throw new IndexOutOfBoundsException("Resizing would lose data");
        //新的容量+1
        newcapacity++;
        //如果扩容后的size和当前容量相同，返回
        if (newcapacity == this.capacity)
            return;
        //创建新队列
        T[] newqueue = newArray(newcapacity);
        //复制队列
        for (int i = 0; i < size; i++)
            newqueue[i] = get(i);
        //赋值
        this.capacity = newcapacity;
        this.queue = newqueue;
        this.head = 0;
        this.tail = size;
    }