1.List 範例

import java.util.HashSet;
import java.util.Set;

public class PaymentSetExample {
    public static void main(String[] args) {
        Set<String> paymentMethods = new HashSet<>();
        paymentMethods.add("CreditCard");
        paymentMethods.add("ATM");
        paymentMethods.add("CVS");
        paymentMethods.add("CreditCard"); // 重複，不會被加入

        System.out.println("可用的付款方式：" + paymentMethods);
    }
}

2.Map 範例

import java.util.HashMap;
import java.util.Map;

public class PaymentMapExample {
    public static void main(String[] args) {
        Map<String, Integer> orderPayments = new HashMap<>();
        orderPayments.put("Order1001", 1500);
        orderPayments.put("Order1002", 2999);
        orderPayments.put("Order1003", 800);

        // 取出某筆訂單的付款金額
        System.out.println("Order1002 的金額: " + orderPayments.get("Order1002"));
    }
}

3.Collection 介面（共通操作）

import java.util.ArrayList;
import java.util.Collection;

public class PaymentCollectionExample {
    public static void main(String[] args) {
        Collection<String> logs = new ArrayList<>();
        logs.add("建立訂單");
        logs.add("付款成功");
        logs.add("寄送Email通知");

        for (String log : logs) {
            System.out.println("處理紀錄: " + log);
        }
    }
}

4. Collections 工具類別（排序、最大最小值）

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class PaymentCollectionsExample {
    public static void main(String[] args) {
        List<Integer> amounts = new ArrayList<>();
        amounts.add(1200);
        amounts.add(500);
        amounts.add(3000);

        Collections.sort(amounts); // 排序
        System.out.println("交易金額排序: " + amounts);

        System.out.println("最大金額: " + Collections.max(amounts));
        System.out.println("最小金額: " + Collections.min(amounts));
    }
}