Daniel on Instagram: "ArrayLists stop being confusing the moment you realize they’re not “magic arrays” — they’re a different tool with different rules. This week you learned how lists grow, how .add() and .remove() actually shift data, and why most ArrayList bugs come from ignoring what’s happening under the hood. Once you understand the movement, ArrayLists become predictable — and predictable code is how you stop losing points on FRQs. Follow for more Java clarity, and DM for AP Computer Scie

【Java】list内の要素を検索する方法を理解しよう！indexOfとcontainsの違いとは？ | ポテパンスタイル