如何在類中添加實例變量？

Question

嗨，我試圖添加動物（老虎，長頸鹿，企鵝）的每個子類的所有空間要求，所以我可以在動物園班級打印出來。用我目前的程序（下面）我得到每個大小的要求是0.加上一些額外的隨機零。幫幫我？？謝謝，麻煩您了！？

public class Zoo { 

    private Animal animal; 
    public int number_animals;//# animals allowed in zoo 
    private List<Animal> animal_list; 
    private String zoo_name; 


    public Zoo(String name){ 
     this.zoo_name = name; 
     animal_list = new ArrayList<Animal>(); 
    } 

    public void addAnimal(Animal obj) { 
      animal_list.add(obj); 
    } 
    public String toString(){ 
     String s = "In zoo " + zoo_name + " there are the following animals:\n"; 
     for (int i = 0; i < animal_list.size(); i++){ 
      s += animal_list.get(i).printDetails() + "\n"; 
     } 
     return s; 
    } 

    public String countAnimals(){  
     return "There are " + animal_list.size() + " animals in " + zoo_name + "."; 
    } 
    public String spaceRequirement(){ 
     int s = 0; 
     int t = 0; 
     int k = 0; 
     for (int i = 0; i < animal_list.size(); i++){ 
      if (animal_list.get(i) instanceof Giraffe){ 
       while (! (animal_list.get(i) instanceof Giraffe)) 
       s += animal_list.get(i).getSpaceRequired(); 
      } 
      System.out.println(s); 
      if (animal_list.get(i) instanceof Penguin){ 
        while (! (animal_list.get(i) instanceof Penguin)) 
        t += animal_list.get(i).getSpaceRequired(); 
      } 
      if (animal_list.get(i) instanceof Tiger){ 
        while (! (animal_list.get(i) instanceof Tiger)) 
        k += animal_list.get(i).getSpaceRequired(); 
      } 

     } 
     return "Total tree height needed: " + t + "\nTotal water volume needed: " + s + "\nTotal grass area needed: " + k; 
    } 
    public void printDetails(){ 
     System.out.println("In zoo " + zoo_name + " there are the following animals:\n" + animal); 
    } 


public class Animal { 

    public String name; 
    public int weight; 
    private String food_type; 
    private int space_area = 0; 
    private Zoo zoo; 
    private Animal animal; 

    public Animal(String name, int weight){ 
     this.name = name; 
     this.weight = weight; 
    }  
    public String getName(){ 
     return this.name; 
    } 
    public int getWeight(){ 
     return this.weight; 
    } 

    public int getSpaceRequired() { 
     return this.space_area; 
    } 

    public void printDailyFoodOrder() { 
     return; 
    } 

    public void setZoo(Zoo zoo){ 
     this.zoo = zoo; 
     this.zoo.addAnimal(this); 
    } 

    public String printDetails() { 
     String a = getName() + " who weighs " + getWeight() + " kg,"; 
     return a; 
     } 


} 

    public class Giraffe extends Animal { 

    private String food_type = "leaves"; 
    private int leaves; 
    private int space_area; 
    private int number_giraffes = 0; 
    public Giraffe[] giraffe_array; 

     public Giraffe(String name, int weight, String food_type, int space_area, int leaves){ 
     super(name, weight); 
     this.food_type = food_type; 
     this.space_area = space_area; 
     this.leaves = leaves;  
    }  
    public int getNumberGiraffes(){ 
     return this.number_giraffes; 
    } 

    public String printDetails(){ 
     return super.printDetails() + " eats " + this.food_type + ", and needs a tree with a mininum height " + this.space_area + " meters."; 
    } 

    public int getSpaceRequired() { 
     return this.space_area; 
    } 
} 

    public class Penguin extends Animal { 

    private String food_type = "fish"; 
    private int food; 
    private int space_area; 

    public Penguin(String name, int weight, int food, int space_area){ 
     super(name, weight); 
     this.food = food; 
     this.space_area = space_area; 
    } 
    public int getSpaceRequired() { 
     return this.space_area; 
    } 



    public void calcPoolSize() { 

    } 
    public String printDetails(){ 
     return super.printDetails() + " eats " + this.food_type + ", and needs a pool sized " + this.space_area + " cubic meters."; 
    } 

} 


public class Test { 

    public static void main(String[] args) { 

     Zoo diego = new Zoo("San Diego"); 
     Animal giffy = new Animal("Giffy", 950); 
     giffy = new Giraffe("Giffy", 950, "Leaves", 15, 100);  
     Animal gunther = new Animal("Gunther", 950); 
     gunther = new Giraffe("Gunther", 950, "Leaves", 15, 100); 
     Animal kevin = new Animal("Kevin", 225); 
     kevin = new Tiger("Kevin", 225, 10, 10); 
     Animal hobbes = new Animal("Hobbes", 200); 
     hobbes = new Tiger("Hobbes", 200, 8, 20); 
     Animal wobbles = new Animal("Wobbles", 25); 
     wobbles = new Penguin("Wobbles", 25, 5, 125); 
     Animal gretchin = new Animal("Gretchin", 15); 
     gretchin = new Penguin("Gretchin", 15, 3, 125); 
     diego.addAnimal(giffy); 
     diego.addAnimal(gunther); 
     diego.addAnimal(wobbles); 
     diego.addAnimal(hobbes); 
     diego.addAnimal(kevin); 
     diego.addAnimal(gretchin); 
     System.out.println(diego); 
     System.out.println(diego.spaceRequirement()); 
    } 

} 

Answer 1

你不需要while循環。

public String spaceRequirement(){ 
    int s = 0; 
    int t = 0; 
    int k = 0; 
    for (int i = 0; i < animal_list.size(); i++){ 
     if (animal_list.get(i) instanceof Giraffe){ 
       s += animal_list.get(i).getSpaceRequired(); 
     } 
     System.out.println(s); 
     if (animal_list.get(i) instanceof Penguin){ 
       t += animal_list.get(i).getSpaceRequired(); 
     } 
     if (animal_list.get(i) instanceof Tiger){ 
       k += animal_list.get(i).getSpaceRequired(); 
     } 

    } 
    return "Total tree height needed: " + t + "\nTotal water volume needed: " + s + "\nTotal grass area needed: " + k; 
}