Question

我想拥有多个类，并希望根据用户输入构造一个类。具体来说，我正在编写文字冒险游戏，并为玩家可以使用的每种“玩家类别”提供了一个类别。我的三个班级扩展了父级“统计”班级。

这是我的代码的一部分：（我使用打印构造函数来提高书写效率）

switch (answer) {
        case 1:
            {
                adv.print("you are a mage");
                mainCharacterMage mainCharacter = new mainCharacterMage();
                break;
            }
        case 2:
            {
                adv.print("you are an assasin");
                mainCharacterAssasin mainCharacter = new mainCharacterAssasin();
                break;
            }
        case 3:
            {
                adv.print("you are a fighter");
                mainCharacterFighter mainCharacter = new mainCharacterFighter();
                break;
            }
        default:
            adv.print("error wrong answer");
            break;
    }
    String printThis = Integer.toString(mainCharacter.getHealth());
    adv.print("your health is "+printThis);

Answer 1

我假定这三个子类的父类称为MainCharacter。

首先，mainCharacter的类型必须为MainCharacter，除非您愿意每次使用instanceof进行mainCharacter检查和强制转换。您需要对mainCharacter进行的每个操作都必须在MainCharacter中定义，而不是在子类中定义。

第二，您需要在mainCharacter之外声明switch，然后在switch中进行定义：

MainCharacter mainCharacter; // Declare it outside
switch (answer) {
        case 1:
            {
                adv.print("you are a mage");
                mainCharacter = new MainCharacterMage(); // Then define it on the inside
                break;
            }
        case 2:
            {
                adv.print("you are an assasin");
                mainCharacter = new MainCharacterAssasin();
                break;
            }
        case 3:
            {
                adv.print("you are a fighter");
                mainCharacter = new MainCharacterFighter();
                break;
            }
        default:
            adv.print("error wrong answer");
            break;
    }

Answer 2

可能是这样的

public interface Character {
  // here is all common method of your Character
}

public class CharacterFactory {
    private class CharacterMage implements Character {
       // here is implementation
    }

    private class CharacterAssasin implements Character {
       // here is implementation
    }

    public Character createCharacter(String characterName) {
         switch (characterName) {
             case "Mage": 
                 return new CharacterMage();

             case "Assasin":
                 return new CharacterAssasin();

             default:
                 throw new IllegalArgumentException("Incorrect character type " + characterName);
    }
}

Answer 3

根据类之间的区别，可以使用一个MainCharacter class和每个类不同的工厂方法来完成。

例如，像这样设置MainCharacter类：

public class MainCharacter{
    public int health;
    public int damage;
    // etc.
    public static MainCharacter buildMage(){
        health = 5;
        damage = 20;
        // etc.
    }
    public static MainCharacter buildAssassin(){
        health = 10;
        damage = 10;
        // etc.
    }
    public static MainCharacter buildMage(){
        health = 20;
        damage = 5;
        // etc.
    }
}

然后按如下所示创建MainCharacter：

switch (answer) {
    case 1:
        {
            adv.print("you are a mage");
            MainCharacter main_character = MainCharacter.buildMage();
            break;
        }
    case 2:
        {
            adv.print("you are an assasin");
            MainCharacter main_character = MainCharacter.buildAssassin();
            break;
        }
    case 3:
        {
            adv.print("you are a fighter");
            MainCharacter main_character = MainCharacter.buildFighter();
            break;
        }

注意：这减少了您必须创建的类的数量，但是仅当类之间的差异只是不同的初始状态时才合适。如果不同的类实际上具有固有的不同方法，那么就需要继承。

如何编写基于用户输入的构造函数？

3 个答案: