如何制作继承对象的数组 - Java

Question

我有抽象类 Animal 和继承类 Fish 和 Dog。 我需要创建鱼和狗的各种对象，并给它们命名和品种，并为它们的移动方式制定方法。 最后，我需要创建一个它们的数组并随机打印 4 次显示它们的名称和品种。

主类：

public class JavaApplication38 {


public static void main(String[] args) {


   Animal[] arr = new Animal[20];

    arr[0] = new Fish("Riby", "Sea Fish");
    arr[1] = new Dog("Any", "Great Dane");
    arr[2] = new Fish("Ribytsa", "River fish");
    arr[3] = new Dog("Jackie", "Pug");
    arr[4] = new Fish("Bobi", "Mix");
    arr[5] = new Dog("Ruby", "Labrador");    

    }

}

动物类

public abstract class  Animal {

  public Animal(String name, String breed){

  } 



   public Animal(){
   }

   public abstract void moving();

}

狗类

Public class Dog extends Animal{


private String breed;
private String name;

public Dog(){
}

 public Pas(String name, String breed){
     this.name = name;
     this.breed =breed;
}


@Override
public void moving() {
    System.out.print("Walk\n");
}

}

鱼类

public class Fish extends Animal {


private String breed;


private String name;

public Fish(){

}

public Fish(String name, String breed){
    this.name = name;
    this.breed= breed;
}

@Override
public void moving(){
    System.out.print("Swims\n");
}

}

问题是，我必须在循环中写什么来通过数组打印名称和品种？

Answer 1

问题是您在Animal 的每个子类中分别定义了name 和breed。您需要在Animal 中创建name 和breed 实例变量。这样一来，Java 就知道每一个 Animal 都有一个 name 和 breed。

public abstract class Animal {
    private String name;
    private String breed;

    public Animal(String name, String breed) {
        this.name = name;
        this.breed = breed;
    }

    public getName() { return name; }
    public getBreed() { return breed; }

    public abstract void moving();
}

public class Dog extends Animal {
    public Dog(String name, String breed) {
        super(name, breed);
    }

    @Override
    public void moving(){
        System.out.print("Walks\n");
    }
}

public class Fish extends Animal {
    public Fish(String name, String breed) {
        super(name, breed);
    }

    @Override
    public void moving(){
        System.out.print("Swims\n");
    }
}

现在您可以为任何Animal 打印name 和breed，无论是Dog 还是Fish。

Animal[] arr = new Animal[6];

arr[0] = new Fish("Riby", "Sea Fish");
arr[1] = new Dog("Any", "Great Dane");
arr[2] = new Fish("Ribytsa", "River fish");
arr[3] = new Dog("Jackie", "Pug");
arr[4] = new Fish("Bobi", "Mix");
arr[5] = new Dog("Ruby", "Labrador");

for (Animal a : arr) {
   System.out.println(a.getName() + " " + a.getBreed());
   a.moving();
}