我如何编写基于用户输入的构造函数？

Question

我想要多个 classes 并且想根据用户输入构建一个。具体来说，我正在写一个文字冒险，并为玩家可以成为的每种 "player class" 类型设置 class。我的三个 classes 扩展了一个父 "stats" class。

这是我的部分代码：（为了提高写作效率，我使用了打印构造函数）

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

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 2

我假设三个子 class 的父 class 称为 MainCharacter。

首先，mainCharacter 必须是 MainCharacter 类型，除非您愿意在每次要使用 mainCharacter 时都进行 instanceof 检查和转换。您需要在 mainCharacter 上执行的每个操作都需要在 MainCharacter 中定义，而不是在子 class 中定义。

其次，你需要在switch之外声明mainCharacter，然后在switch中定义它：

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 3

根据 classes 之间的差异，这可以只用一个 MainCharacter class 和不同的 factory 方法 来完成每个 class.

例如像这样设置 MainCharacter class：

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.
    }
}

然后像这样创建 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 classes 的数量，但是只有当 classes 之间的差异只是不同的初始统计数据时才适用。如果不同的 classes 实际上有本质上不同的方法，那么就需要继承。

我如何编写基于用户输入的构造函数？

how can i write a user input based constructor?

java

project