Java中动态列表多行格式化输出教程：以逗号分隔每行固定数量的字符串

public void displayInventoryIncorrect() {
    List<String> inventory = List.of("Small Bottle", "Large Bottle"); // 假设只有两个物品
    StringBuilder resultBuilder = new StringBuilder("Inventory: \n");
    String format = "%s, %s, %s %n"; // 固定三个占位符

    // 错误示范：直接尝试格式化整个列表或拼接的字符串
    // 这里如果inventory.size()不是3的倍数，就会出问题
    // resultBuilder.append(String.join(",", inventory)); // 这样会将所有物品放在一行
    // System.out.format(format, resultBuilder.toString()); // 错误，因为format需要三个参数

    // 如果尝试循环append，然后统一format，也无法解决参数匹配问题
    // for (String item : inventory) {
    //     resultBuilder.append(item); // 只是简单拼接，无法实现每行三个
    // }
    // System.out.format(format, "arg1", "arg2"); // 如果只有两个arg，format需要三个就会报错
}

import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;

public class InventoryDisplayFormatter {

    // 模拟玩家的背包物品列表
    private List<String> inventory;

    public InventoryDisplayFormatter(List<String> items) {
        this.inventory = new ArrayList<>(items); // 复制一份，防止外部修改
    }

    /**
     * 显示背包物品，每行固定数量，逗号分隔。
     *
     * @param itemsPerLine 每行显示的物品数量
     */
    public void displayInventory(int itemsPerLine) {
        if (inventory.isEmpty()) {
            System.out.println("Inventory: (Empty)");
            return;
        }

        System.out.println("Inventory:");
        int size = inventory.size();

        // 遍历列表，每次跳过itemsPerLine个元素
        for (int i = 0; i < size; i += itemsPerLine) {
            // 计算当前行的结束索引，确保不超过列表大小
            int endIndex = Math.min(i + itemsPerLine, size);

            // 提取当前行的子列表
            List<String> currentLineItems = inventory.subList(i, endIndex);

            // 使用String.join()将子列表中的元素用逗号和空格连接起来
            System.out.println(String.join(", ", currentLineItems));
        }
    }

    public static void main(String[] args) {
        // 测试数据1：刚好是3的倍数
        List<String> items1 = Arrays.asList(
            "Sword", "Shield", "Potion",
            "Map", "Compass", "Key",
            "Gold Coin", "Silver Ring", "Magic Dust"
        );
        InventoryDisplayFormatter formatter1 = new InventoryDisplayFormatter(items1);
        System.out.println("--- Test Case 1: Items are a multiple of 3 ---");
        formatter1.displayInventory(3);
        System.out.println();

        // 测试数据2：不是3的倍数，最后一行不足3个
        List<String> items2 = Arrays.asList(
            "Axe", "Bow", "Arrow",
            "Torch", "Rope", "Water Bottle",
            "Bread", "Apple" // 只有两个
        );
        InventoryDisplayFormatter formatter2 = new InventoryDisplayFormatter(items2);
        System.out.println("--- Test Case 2: Items not a multiple of 3 ---");
        formatter2.displayInventory(3);
        System.out.println();

        // 测试数据3：只有少量物品，不足一行
        List<String> items3 = Arrays.asList("Scroll", "Gem");
        InventoryDisplayFormatter formatter3 = new InventoryDisplayFormatter(items3);
        System.out.println("--- Test Case 3: Few items, less than one line ---");
        formatter3.displayInventory(3);
        System.out.println();

        // 测试数据4：空列表
        List<String> items4 = new ArrayList<>();
        InventoryDisplayFormatter formatter4 = new InventoryDisplayFormatter(items4);
        System.out.println("--- Test Case 4: Empty inventory ---");
        formatter4.displayInventory(3);
        System.out.println();
    }
}

--- Test Case 1: Items are a multiple of 3 ---
Inventory:
Sword, Shield, Potion
Map, Compass, Key
Gold Coin, Silver Ring, Magic Dust

--- Test Case 2: Items not a multiple of 3 ---
Inventory:
Axe, Bow, Arrow
Torch, Rope, Water Bottle
Bread, Apple

--- Test Case 3: Few items, less than one line ---
Inventory:
Scroll, Gem

--- Test Case 4: Empty inventory ---
Inventory: (Empty)