用java写一个300行的面向对象之宠物大作战，包括分支，循环等等

以下是一个简单的面向对象之宠物大作战的Java程序，共计约300行，包括分支、循环等等。为了简化代码，一些细节和异常处理等内容并未完全考虑。代码中的注释可以帮助理解。

import java.util.Scanner;

/**
 * 宠物类
 */
class Pet {
    private String name;    // 名字
    private String type;    // 种类
    private int level;      // 等级
    private int hp;         // 生命值
    private int attack;     // 攻击力
    private int defense;    // 防御力

    public Pet(String name, String type) {
        this.name = name;
        this.type = type;
        this.level = 1;
        this.hp = 100;
        this.attack = 10;
        this.defense = 5;
    }

    public String getName() {
        return name;
    }

    public String getType() {
        return type;
    }

    public int getLevel() {
        return level;
    }

    public int getHp() {
        return hp;
    }

    public int getAttack() {
        return attack;
    }

    public int getDefense() {
        return defense;
    }

    public void attack(Pet enemy) {
        int damage = this.attack - enemy.getDefense();
        if (damage < 0) {
            damage = 0;
        }
        enemy.hp -= damage;
        System.out.println(this.name + "攻击了" + enemy.getName() + "，造成了" + damage + "点伤害。");
    }

    public void defend() {
        this.defense += 5;
        System.out.println(this.name + "使用了防御技能，防御力提高了。");
    }

    public void levelUp() {
        this.level++;
        this.hp += 10;
        this.attack += 5;
        this.defense += 2;
        System.out.println(this.name + "升级了，生命值、攻击力、防御力都提高了。");
    }

    public void showInfo() {
        System.out.println("宠物名字：" + this.name);
        System.out.println("宠物种类：" + this.type);
        System.out.println("宠物等级：" + this.level);
        System.out.println("宠物生命值：" + this.hp);
        System.out.println("宠物攻击力：" + this.attack);
        System.out.println("宠物防御力：" + this.defense);
    }
}

/**
 * 玩家类
 */
class Player {
    private String name;    // 名字
    private int level;      // 等级
    private int exp;        // 经验值
    private int gold;       // 金币
    private Pet pet;        // 拥有的宠物

    public Player(String name) {
        this.name = name;
        this.level = 1;
        this.exp = 0;
        this.gold = 0;
        this.pet = null;
    }

    public String getName() {
        return name;
    }

    public int getLevel() {
        return level;
    }

    public int getExp() {
        return exp;
    }

    public int getGold() {
        return gold;
    }

    public Pet getPet() {
        return pet;
    }

    public void buyPet() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请选择要购买的宠物种类（1.狗狗 2.猫咪 3.兔子）：");
        int type = scanner.nextInt();
        String name = "";
        switch (type) {
            case 1:
                name = "旺财";
                break;
            case 2:
                name = "咪咪";
                break;
            case 3:
                name = "小白";
                break;
            default:
                System.out.println("输入有误，购买失败。");
                return;
        }
        Pet pet = new Pet(name, type == 1 ? "狗狗" : type == 2 ? "猫咪" : "兔子");
        if (this.gold < 50) {
            System.out.println("金币不足，购买失败。");
            return;
        }
        this.gold -= 50;
        this.pet = pet;
        System.out.println("购买成功，您现在拥有一只" + this.pet.getType() + "，名字叫做" + this.pet.getName() + "。");
    }

    public void useItem() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请选择要使用的道具（1.药水 2.防御道具）：");
        int type = scanner.nextInt();
        switch (type) {
            case 1:
                if (this.pet == null) {
                    System.out.println("您还没有宠物，使用失败。");
                    return;
                }
                this.pet.getHp += 20;
                System.out.println("您的宠物回复了20点生命值。");
                break;
            case 2:
                if (this.pet == null) {
                    System.out.println("您还没有宠物，使用失败。");
                    return;
                }
                this.pet.defend();
                break;
            default:
                System.out.println("输入有误，使用失败。");
                break;
        }
    }

    public void fight() {
        if (this.pet == null) {
            System.out.println("您还没有宠物，无法进行战斗。");
            return;
        }
        Pet enemy = new Pet("敌人", "野生" + (int) (Math.random() * 3 + 1));
        System.out.println("你遇到了一只" + enemy.getType() + "，准备开始战斗！");
        while (this.pet.getHp() > 0 && enemy.getHp() > 0) {
            Scanner scanner = new Scanner(System.in);
            System.out.println("请选择要进行的操作（1.攻击 2.防御）：");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    this.pet.attack(enemy);
                    break;
                case 2:
                    this.pet.defend();
                    break;
                default:
                    System.out.println("输入有误，回合结束。");
                    break;
            }
            if (enemy.getHp() > 0) {
                enemy.attack(this.pet);
            }
        }
        if (this.pet.getHp() > 0) {
            System.out.println("战斗胜利，获得了100点经验值和50金币。");
            this.exp += 100;
            this.gold += 50;
            if (this.exp >= this.level * 100) {
                this.level++;
                this.exp = 0;
                System.out.println("恭喜你升级了，当前等级为" + this.level + "。");
            }
            this.pet.levelUp();
        } else {
            System.out.println("战斗失败，宠物死亡。");
            this.pet = null;
        }
    }

    public void showInfo() {
        System.out.println("玩家名字：" + this.name);
        System.out.println("玩家等级：" + this.level);
        System.out.println("玩家经验值：" + this.exp);
        System.out.println("玩家金币：" + this.gold);
        if (this.pet != null) {
            System.out.println("玩家拥有的宠物：");
            this.pet.showInfo();
        } else {
            System.out.println("玩家还没有宠物。");
        }
    }
}

/**
 * 程序主类
 */
public class PetBattle {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("欢迎进入宠物大作战！");
        System.out.println("请输入您的名字：");
        String name = scanner.nextLine();
        Player player = new Player(name);
        while (true) {
            System.out.println("==================");
            System.out.println("请选择要进行的操作：");
            System.out.println("1.购买宠物");
            System.out.println("2.使用道具");
            System.out.println("3.战斗");
            System.out.println("4.查看信息");
            System.out.println("5.退出游戏");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    player.buyPet();
                    break;
                case 2:
                    player.useItem();
                    break;
                case 3:
                    player.fight();
                    break;
                case 4:
                    player.showInfo();
                    break;
                case 5:
                    System.out.println("感谢您的游玩，再见！");
                    return;
                default:
                    System.out.println("输入有误，请重新选择。");
                    break;
            }
        }
    }
}