Question

我必须创建包含猫和狗的宠物列表，我必须使用继承。 Pet class wil包含name变量，Dog类将包含name和weight变量，Cat类将包含name和coatColor变量。

我必须创建一个包含下面菜单的Test类。

添加狗
添加猫
删除狗
删除猫
列出狗
列出猫
列出所有宠物
显示狗的最小，最大和平均重量
退出

我写过每节课，但我无法完成，我需要你的帮助。

我的课程如下。（如果我做错了，请编辑并告诉我，我认为我做错了什么）

宠物等级：

public class Pet{
    private static String name;

    protected String getName(){
        return name;
    }

    protected void setName(String newName){
        name = newName;
    }

    public Pet(String petName) {
        name = petName;
    }
}

狗类：

public class Dog extends Pet{       
    private Double weight;      
    protected double getWeight(){
        return weight;
    }

    protected void setWeight(double newWeight){
        weight = newWeight;
    }

    public Dog(double dogWeight, String petName){
        super(petName);
        weight = dogWeight;

    }
}

猫类：

public class Cat extends Pet{       
    private String coatColor;       
    protected String getWeight(){
        return coatColor;
    }

    protected void setColor(String newColor){
        coatColor = newColor;
    }

    public Cat(String petName, String coatColor){
        super(petName);
        this.coatColor = coatColor;
    }
}

PetTest课程：

import java.util.*;

public class PetTest
{
    //i made it static to make all method to be able to see it.
    static ArrayList<Pet> mainList = new ArrayList<Pet>();
    static Iterator<Pet> mainIter = mainList.iterator();
    static Scanner keyboard = new Scanner(System.in);

    static Pet cat2342 = new Cat("mirnav", "beyaz");
    public static void listDogs()
    {
        while(mainIter.hasNext())
        {
            for(Pet dog: mainList)
            {
                System.out.println(dog);
            }//end of for loop

        }//end of while loop
    }//end of listDogs method

    public static void listCats()
    {
        while(mainIter.hasNext())
        {
            for(Pet cat: mainList)
            {
                System.out.println(cat);
            }//end of for loop

        }//end of while loop
    }//end of listCats method

    public static void addDog(String dogName,Double dogWeight)
    {
        Pet dog = new Dog(dogName, dogWeight);
        mainList.add(dog);
    }//end of addDog method

    public static void addCat(String catName, String furColor)
    {
        Pet cat = new Cat(catName, furColor);
        mainList.add(cat);
    }//end of addCat method

    public static void removeDog(String dogName)
    {
        while (mainIter.hasNext())
        {
            for(Pet pet : mainList)
            {
                if(pet.getName().equals(dogName))
                {
                    mainIter.remove();
                }//end of if statement
            }//end of for loop


        }//end of while loop

    }//end of removeDog method


    public static void removeCat(String catName)
    {
        while (mainIter.hasNext())
        {
            for(Pet pet : mainList)
            {
                if(pet.getName().equals(catName))
                {
                    mainIter.remove();
                }//end of if statement
            }//end of for loop


        }//end of while loop

    }//end of removeCat method


    public static void main(String[] args)
    {

        System.out.println("1. Add dog ");
        System.out.println("2. Add cat");
        System.out.println("3. Remove dog");
        System.out.println("4. Remove cat");
        System.out.println("5. List dogs");
        System.out.println("6. List cats");
        System.out.println("7. List all pets");
        System.out.println("8. Show min, max and average weight of dogs");
        System.out.println("0. Quit");
        int action = keyboard.nextInt();


        Scanner parameter1 = new Scanner(System.in);
        Scanner parameter2 = new Scanner(System.in);

        while(action != 0)
        {
        switch(action)
        {
        case 1: 
            System.out.println("Type in the name of the dog that you want to add.");
            String dogName = parameter1.next();
            System.out.println("Type in the weight of the dog that you want to add.");
            Double dogWeight = parameter2.nextDouble();
            addDog(dogName,dogWeight);
            showMenu();


        case 2:
            System.out.println("Type in the name of the cat that you want to add.");
            String catName = parameter1.next();
            System.out.println("Type in the color of the cat that you want to add.");
            String furColor = parameter2.next();
            addCat(catName,furColor);



        case 3:
            System.out.println("Type in the name of dog that you want to remove.");
            String dogToRemove = parameter1.next();
            removeDog(dogToRemove);



        case 4:
            System.out.println("Type in the name of dog that you want to remove.");
            String catToRemove = parameter1.next();
            removeDog(catToRemove);



        case 5:
            listDogs();

        case 6:
            listCats();




        }//end of switch statement

        }//end of while loop

    }//end of main method



}//end of the class

Answer 1

制作Cat＆amp; Dog类继承自Pet类，如下所示：

public class Cat extends Pet {...}
public class Dog extends Pet {...}

如果您希望子类在没有getter / setter方法的情况下使用它，name类中的Pet变量也可以设置为protected。（取决于您的要求）

Answer 2

你所做的大部分是正确的。虽然照顾好一些事情：

您的cat类中存在错误（对于coatColor getter）：错误的名称
您的方法addDog实际上会添加一只令人困惑的猫

现在，您需要的有趣的东西（工具）：

每个动作都需要一种方法（添加猫，添加狗等）
您需要在主列表中添加您创建的宠物：mainList.add(...)
您宁愿使用开关/案例语法来调用您的方法
要删除猫或狗，您可能需要指明要删除哪一个（或者可能只添加最后一个）
要列出狗或猫，您需要迭代mainList并仅保留那些类型合适的人：使用instanceof运算符
要显示狗的最小/最大和平均重量，您需要在列表上进行迭代，并保留所有这些重量。

无论如何，我可以更具体地指出每一点，但这对你来说并不好玩，因为你需要自己寻找解决方案。有更好的方法可以做到这一点（例如使用像Guava这样的框架），但这是你的下一步！

Generic ArrayList和一个自动将项添加到Array的菜单

2 个答案: