一、从动态数组到二维 ArrayList：核心概念 ArrayList 是数组（Array）的动态版本。原生数组在声明时必须预定义长度，而 ArrayList 内部维护一个可扩容的底层数组，当元素数量超过当前容量时会自动增长，因此使用者在多数场景下无需关心容量上限。

原创 最新推荐文章于 2026-09-17 09:51:31 发布 · 220 阅读 ArrayList作为Java集合框架中最常用的动态数组实现，其底层通过数组存储 ...

main Ex11-Convert HashSet to ArrayList .md Ex12-Add Elements from an Array into a TreeSet.md Ex13-Elements of an Array.md Ex14-First Unique Number in a Stream.md Ex15-Value Existence Check in a ...

An array in Java is a container object that holds a fixed number of values of a single type. The length of an array is established when the array is created and cannot be changed.

ArrayList is a dynamic array. In other words, you don't need to specify the size at the beginning, you can store values one after another as you go.

When processing data in arrays or lists, do you just reach for a for-loop (or enhanced for-loop) by default? When learning Java, the first thing that comes to mind when extracting data with specific ...