java - 根据构造函数参数构造子类？

Question

如果我有一个抽象类及其子类:

public abstract class Animal{
  //other methods..
}

public class Dog extends Animal{
  private int legs;
  public Dog(int legs){
      this.legs = legs;
  }
}

public class Fish extends Animal{
  private int legs;
  private int speed;

  public Fish(int legs, int speed){
      this.legs = legs;
      this.speed = speed;
  }
}

有没有办法通过简单地使用构造函数重载来初始化新的 Dog 或 Fish？

类似于:

public void createNewAnimal(int new_legs, int new_speed){
  new Animal(new_legs, new_speed) //Makes fish.
  new Animal(new_legs) //Makes dog.
}

Answer 1

构造函数是其类的一部分，因此您不能重载它来创建不同的类。但是，您可以拥有一个具有重载方法的工厂:

public class AnimalFactory {
    public static Animal create(int legs, int speed) {
        return new Fish(legs, speed);
    }

    public static Animal create(int speed) {
        return new Dog(speed);
    }
}