ArrayList默认初始化大小

public static void main(String[] args) throws Exception {
        List<Object> list = new ArrayList<>();
        Field field = ArrayList.class.getDeclaredField("elementData");
        field.setAccessible(true); // 设置为可访问
        Object[] elementData = (Object[]) field.get(list);

        int capacity = elementData.length;
        System.out.println("ArrayList capacity: " + capacity);
        list.add("1");
        list.add("2");
        list.add("3");
        list.add("4");
        list.add("5");
        list.add("6");
        list.add("7");
        list.add("8");
        list.add("9");
        list.add("10");

        list.add("11");

        elementData = (Object[]) field.get(list);
        capacity = elementData.length;
        System.out.println("ArrayList capacity: " + capacity);

        System.out.println("list = " + list);
    }

源码：

//| Constructs an empty list with an initial capacity of ten.
//构造一个初始容量为10的空列表。
  public ArrayList() {
        this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
    }


ArrayList默认大小为10，当第11次进行添加操作时，按照初始大小的1.5倍进行扩容。