Java Setter未按预期更新值：理解对象生命周期与引用

public class MainChar {
    private int health = 100;
    private int defence = 25;
    private int strength = 15;
    private int mana = 10;

    // Getter 方法
    public int gethealth(){ return health; }
    public int getStrength() { return strength; }
    public int getDefence() { return defence; }
    public int getMana() { return mana; }

    // Setter 方法
    public void setDefence(int newDefence) { this.defence = newDefence; }
    public void setHealth(int newHealth) { this.health = newHealth; }
    public void setMana(int newMana) { this.mana = newMana; }
    public void setStrength(int newStrength) { this.strength = newStrength; }
}

public class GameMenu { // 假设这是包含菜单逻辑的类
    // ... startmenu() 方法省略，它会调用 SouthValley(path)

    public static void SouthValley(int selectedPath){
        MainChar Stats = new MainChar(); // 关键问题所在：每次调用都创建新对象
        do {
            switch(selectedPath){
                // ... case 1-4 省略
                case 5:
                    System.out.println("--------------------------------");
                    System.out.println("Defence: " + Stats.getDefence()); // 打印当前 Stats 对象的防御
                    // ... 打印其他属性
                    startmenu(); // 重新显示菜单
                    break;
                case 6:
                    Stats.setDefence(50); // 修改当前 Stats 对象的防御
                    System.out.println("防御已更新为: " + Stats.getDefence());
                    startmenu(); // 重新显示菜单
                    break;
                default:
                    startmenu();
                    break;
            }
        }
        while(selectedPath < 7); // 这个循环条件在 startmenu() 被调用后，实际不会继续执行
    }
}

MainChar Stats = new MainChar();

import java.util.Scanner;

public class GameMenu {

    // 将 MainChar 对象声明为静态成员变量，确保只有一个实例
    private static MainChar playerStats = new MainChar();

    public static void startmenu(){
        int path;
        Scanner startscan = new Scanner(System.in);
        System.out.println("-----------------------");
        System.out.println("Enter Shop : 1");
        System.out.println("Enter house : 2");
        System.out.println("Enter town square : 3");
        System.out.println("Leave town : 4");
        System.out.println("Check stats : 5");
        System.out.println("Update defence : 6"); // 添加更新防御的选项
        System.out.println("Chosen path: ");
        path = startscan.nextInt();
        // 将 playerStats 对象传递给 SouthValley 方法，或者 SouthValley 直接访问静态变量
        SouthValley(path);
    }

    public static void SouthValley(int selectedPath){
        // 不再在这里创建新的 MainChar 对象，而是使用类级别的 playerStats
        do {
            switch(selectedPath){
                case 1:
                    System.out.println("You Entered shop");
                    System.out.println("-----------------------------");
                    break;
                case 2:
                    System.out.println("You Entered you house");
                    break;
                case 3:
                    System.out.println("You Entered Town Square");
                    break;
                case 4:
                    System.out.println("You left the town");
                    startmenu(); // 离开后重新显示菜单
                    break;
                case 5:
                    System.out.println("--------------------------------");
                    System.out.println("Defence: " + playerStats.getDefence()); // 访问同一个 playerStats 对象的防御
                    System.out.println("Strength: " + playerStats.getStrength());
                    System.out.println("Mana: " + playerStats.getMana());
                    System.out.println("Health: " + playerStats.gethealth());
                    startmenu(); // 重新显示菜单
                    break;
                case 6:
                    playerStats.setDefence(50); // 修改同一个 playerStats 对象的防御
                    System.out.println("防御已更新为: " + playerStats.getDefence());
                    startmenu(); // 重新显示菜单
                    break;
                default:
                    startmenu();
                    break;
            }
        }
        while(selectedPath < 7); // 注意：这个 do-while 循环在这里可能不是最佳实践，因为 startmenu() 会递归调用。
                                  // 更好的做法是让 SouthValley() 执行一次后返回，由 startmenu() 的外部循环控制。
    }

    public static void main(String[] args) {
        startmenu(); // 启动菜单
    }
}