java - 初始化抽象类的一般变体

Question

我有两个抽象类:Char 和Weapon。每个都有两个衍生类别:国王和巨魔，以及俱乐部和剑。

角色总是拥有武器，但未指定类型。因此，在构建 Char 类时，我无法初始化正确的类型。另外，在选择角色时，我同样无法初始化正确的类型。

Is it wrong to initialise an abstract class? How can one initialise a class of one sort and then change the variable class? Provided the new type is a trivially different inheritation of the same parent class? Or should one go about it completely differently?

很可能我什至都没有理解抽象类的概念。我是 Java 和纯 OOP 新手。

public class Player{
    private Char c;                   // Wrong?

    public void changeChar(int charID, int wepID){
        switch(charID){
            case 1: c = new King(wepID); break;
            case 2: c = new Troll(wepID); break;
        }
    }

    public void fight(){
        c.fight();
    }
}

abstract class Char{
    protected String name;
    public Weapon weapon;         // Wrong?

    Char(int wepID){
        switch(wepID){
            case 1: weapon = new Sword(); break;
            case 2: weapon = new Club(); break;
        }
    }

    public void fight(){
        weapon.useWeapon(name);
    }
}

abstract class Weapon{
    protected String wepName;
    public void useWeapon(String user){
        System.out.println(user + " fights with " + wepName);
    }
}

class Club extends Weapon{
    Club(){
        wepName = "Club";
    }
}

class Sword extends Weapon{
    Sword(){
        wepName = "Sword";
    }
}

class Troll extends Char{
    Troll(int wepID){
        super(wepID);
        name = "Troll";
    }
}

class King extends Char{
    King(int wepID){
        super(wepID);
        name = "King";
    }
}

Answer 1

您无法实例化抽象类。更明智的方法是为 Char 的构造函数提供一个 Weapon 实例作为参数 - 您可以简单地在 Char 中使用它。

abstract class Char{
    protected String name;
    public Weapon weapon;

    Char(Weapon weapon){
        this.weapon = weapon;
    }

    public void fight(){
        weapon.useWeapon(name);
    }
}

class Troll extends Char{
    Troll(Weapon weapon){
        super(weapon);
        name = "Troll";
    }
}

以及稍后在您的代码中:

Char troll = new Troll (new Club());