Java——继承和多态

Question

说明如下:创建一个包含 main 方法的 Main 类。实现main 方法中包含以下内容:

– 使用重载构造函数从常规类创建对象

– 测试所有实例方法(即 setter、getter、重载、覆盖)

——分配给子对象的父引用

——传递多态对象的方法调用

我被困在我的家长类(class)，即雨林中。接下来我应该做什么？

雨林类

//INHERITANCE                                                      
  package com.ancient;                                              
  public class Rainforest                                                
  {                                         
  public static void main(String[] args)                                 
  }

Rainforest Class - Inherits Parent and Child

哺乳动物类(父类)

//PARENT CLASS                                                     
  package com.ancient;                                              
  public class Mammal                                                    
  {
//INSTANCE VARIABLES
private String type;
private double speed;

//CONSTRUCTOR
public Mammal(String type, double speed)
{
    this.type = type;
    this.speed = speed;
}

//SETTERS
public void setType(String type) 
{
    this.type = type;
}

public void setSpeed(double speed) 
{
    this.speed = speed;
}

//GETTERS
public String getType() 
{
    return type;
}

public double getSpeed() 
{
    return speed;
}

//OVERRIDDEN
public void hunt(int Food)//int Food is the quantity - how many does the eagle he hunts?
{
    System.out.println("The Bald eagle preys " + Food + "animals within a day to survive.");
}

}

Mammal Class - Part 1 Mammal Class - Part 2

鸟(子类)

package com.ancient;                                                
 public class Bird extends Mammal                                        
 {                                                                  
 public Bird(String type, double speed) 
{
    super(type, speed);
}

//OVERRIDDING
public void hunt(int Food)//int Food is the quantity - how many does the eagle he hunts?
{
    System.out.println("The Bald eagle will prey " + Food + "animals within a day to survive.");                                                  
}                                                                        
}

Bird - Child Class

我的项目内容 Project content > src > package (library) > regular (2) and main classes (1)

现在，这里的问题是:我的构造函数未定义。我应该制作一个新包并向其中插入 Rainforest 类吗？或者我的哺乳动物和鸟类类中的对象有问题？

Answer 1

您的 Mammal 类中有一个接受参数的构造函数，但您尝试在不传递参数的情况下实例化对象。