为对象分配常量

Question

public abstract class Animal {
private int weight;
private int height;

public Animal (int weight, int height) {
setWeight(weight);
setHeight(height);
}

public int getWeight() {
    return weight;
}
public void setWeight(int weight) {
     this.weight = weight;
}

public int getHeight() {
    return height;
}

public void setHeight(int height) {
    this.height = height;
}
}

这是一个子类

public class Dog extends Animal {

public static final int ANIMALNUMBER= 1;
public static final int MAXIMUMNUMBERALLOWED= 5;

//the constructor
public Dog (int weight, int height, int animalNumber, int maximumNumberAllowed) {
    super(weight, height)
    Dog.animalNumber = ANIMALNUMBER;
    Dog.maximumNumberAllowed = MAXIMUMNUMBERALLOWED;
}
}

这是另一个子类

public class Cat extends Animal {

public static final int ANIMALNUMBER= 2;
public static final int MAXIMUMNUMBERALLOWED= 10;

//the constructor
public Cat (int weight, int height, int animalNumber, int maximumNumberAllowed) {
    super(weight, height)
    Cat.animalNumber = ANIMALNUMBER;
    Cat.maximumNumberAllowed = MAXIMUMNUMBERALLOWED;
}
}

我最终想要的是这样的：

这不仅表示：不能分配最后一个字段dog.animalnumber，而且我认为它也行不通。有什么建议吗？

提前感谢！

Answer 1

所以对于每只狗，动物数量应该是1，对于每只猫，动物数量应该是2。

你把事情搞得太复杂了。最简单的解决方案是删除构造函数参数并保持AnimalNumber不变。

但是

 public abstract class Animal {
  // common fields
   public Animal (int weight, int height) {
    // initialize
   }

   public abstract sting giveSound();
}

public class Dog extends Animal {
   @Override
   public  sting giveSound(){
     return "Wooff";
}


public class Cat extends Animal {
   @Override
   public  sting giveSound(){
     return "Meaw";
}

public class Rabbit extends Animal {
   @Override
   public  sting giveSound(){
     return "";
}

我得承认这是个拐角处的案子...

我可以根据他们的班级来计算吗？

是，通过使用映射:

 public abstract class Animal {
   public addToCount(Map<String,Integer> counters){
     // gets the class name of the child that has been called *new* on...
     String myClassName =  getClass().getName(); 
     Integer oldCount = conters.getOrDefault(myClassName, Integer.ZERO);
     conters.put(myClassName,oldCount.add(Integer.ONE));
   }
}