java - 无法将 A 类转换为 B 类

Question

访问字段的正确方法是什么 level来自 Minotaur 的实例？在 for (int i =0 ; i < ((Monster) this).level ; i++) 中出错这是Cannot cast from Player to Monster .

package player;

import monsters.*;

public class Player extends GameCharacter {

      public void performAttackOn(GameCharacter who){

    if (who instanceof Monster ){

        for (int i =0 ; i < ((Monster) this).level ; i++) { // << 

                 }

    public static  class Minotaur extends Monster{ // << nested class which is being created and there is need to access it's level

        public Minotaur () {

              type = "Minotaur";

        }
    }

}

---

package monsters;

public class Monster extends GameCharacter{

    public int level = 1;
}

---

package monsters;

public abstract class GameCharacter{

public static  class Minotaur extends Monster{

        public Minotaur(){
            type = "Minotaur";
             hitPoints = 30;
             weapon = new Weapon.Sword();

        }
    }
}

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Minotaur应该扩展 monsters.GameCharacter , monsters.Monster并覆盖 Player.player一些继承自monsters.GameCharacter的方法

Answer 1

有GameCharacter接口(interface)定义一个getLevel()方法 Monster和 Player两者都实现。

public interface GameCharacter
{
  public int getLevel( );
}

完成后，您就可以利用 polymorphism甚至不需要转换。

---

还有，你真的是想投this吗？这是类型 Player , 输入 Monster ？或者你的意思是:

public void performAttackOn(GameCharacter who)
{
    for (int i =0 ; i < who.getLevel( ) ; i++)
    {
      // do stuff...
    }
}