我很确定在 java 中你不能将一个类设为静态，除非它是一个内部类；但这超出了您的问题的重点。
您必须强制转换，因为您无法匹配方法的正确原型private void catAttack(Cat other)或private void catAttack(Dog other)与catAttach(Animal other).
为了解决这个问题，您对超类或接口进行编程。
通常以这种方式完成：
public interface Animal {
public void attack(Animal other);
}
public class Cat implements Animal {
public void attack(Animal other) {
/* TODO: implement attack method */
}
}
public class Dog implements Animal {
public void attack(Animal other) {
/* TODO: implement attack method */
}
}
如果你仔细想想，这种方法是有道理的。ACat在这种情况下，有其自身的攻击性质。您可以执行以下操作：
public class Cat implements Animal {
public void attack(Animal other) {
if (this.equals(other)) {
System.out.println("The Cat won't fight itself.");
} elsif (other instanceof Cat) {
System.out.println("Cats are friendly to one another, so the Cat forfeits the fight!");
} elsif (other instanceof Dog) {
System.out.println("Cats hate Dogs, so the Cat viciously attacks the Dog!");
} else {
System.out.println("The Cat seems to be unamused by the other animal, and walks away...");
}
}
你可以让它变得更复杂：
public class MountainLion extends Cat {
@Override
public void attack(Animal other) {
System.out.println("Mountain Lions do not like to be challenged and will strike down any predator with the fire inside their heart!");
}
}
但是在使用它们的类中，您只需遵循接口模式，如下所示：
public class AnimalKingdom {
public static void main(final String[] args) {
Animal cat = new Cat(); // could be read in from something like Spring using context.getBean("catObject", Animal.class);
Animal dog = new Dog(); // same as above...
Animal randomAnimalType = new MountainLion(); // same as above...
cat.attack(cat);
cat.attack(dog);
cat.attack(randomAnimalType);
dog.attack(cat);
dog.attack(dog);
dog.attack(randomAnimalType);
randomAnimalType.attack(cat);
randomAnimalType.attack(dog);
randomAnimalType.attack(randomAnimalType); // this doesn't use super, doesn't check if the animal is the same instance...
}
}
关键是，如果我现在可以创建 AnimalKingdom 的行为而不用担心它是什么类型的 Animal，那么它就是一个 Animal（所以它遵循 Animal 接口）。如果我使用某种框架（例如 Spring），我可以动态注入基于一些外部配置文件运行的内容，以创建许多可能的场景，而无需复制和粘贴或重新编写代码。
希望这会有所帮助。
谢谢