数组跟list的使用

Question

Person[] p = new Person[10];//Person是自定义的一个类型 ArrayList<Person> pList = new ArrayList<Person>(); 上边的p跟pList都能用来存放person类型的数据,怎么选择?ArrayList可以实现的功能数组也能实现,为啥会有ArrayList呢?

Answer 1

ArrayList底层就是Object数组
 transient Object[] elementData
不过它可以动态扩容，这是它的扩容方法
 private void grow(int minCapacity) {
        // overflow-conscious code
        int oldCapacity = elementData.length;
        int newCapacity = oldCapacity + (oldCapacity >> 1);
        if (newCapacity - minCapacity < 0)
            newCapacity = minCapacity;
        if (newCapacity - MAX_ARRAY_SIZE > 0)
            newCapacity = hugeCapacity(minCapacity);
        // minCapacity is usually close to size, so this is a win:
        elementData = Arrays.copyOf(elementData, newCapacity);
    }