Java 容器基礎：ArrayList 存儲自定義對象示例

Java 容器基礎：ArrayList 存儲自定義對象示例

展示如何使用 ArrayList 存儲自定義實體類 Basicinfo，並通過迭代器遍歷輸出。適合初學者理解集合框架基本用法。

實體類

public class Basicinfo {
    private String name;
    private float price;
    private String color;

    public Basicinfo() {}
    public Basicinfo(String name, float price, String color) {
        this.name = name; this.price = price; this.color = color;
    }
    public String info() { return name + "=>" + price + "=>" + color; }
    // getter/setter 省略
}

主程序

public class Learn {
    public static void main(String[] args) {
        List<Basicinfo> list = new ArrayList<>();
        list.add(new Basicinfo("虎頭牌筆記本", 3.5f, "red"));
        list.add(new Basicinfo("A4紙", 3.5f, "white"));
        list.add(new Basicinfo("B2鉛筆", 3.5f, "black"));

        Iterator<Basicinfo> it = list.iterator();
        while (it.hasNext()) {
            System.out.println(it.next().info());
        }
    }
}

輸出

虎頭牌筆記本=>3.5=>red
A4紙=>3.5=>white
B2鉛筆=>3.5=>black

關鍵點提示

• 使用泛型 List<Basicinfo> 避免強轉與運行時錯誤；
• 優先使用 for-each 或 forEach 簡化遍歷；
• ArrayList 底層動態數組，隨機訪問快，中間插刪慢。