Java多态方法

Question

我目前正在完成大学模拟考试，准备夏季考试。下面是我到目前为止已经完成的代码:我正在努力完成作业的一部分。它要求我做的是:“在 tester02 中，创建一个名为 startRobot 的方法，该方法将是一个多态方法。该方法将接受 Robot 类型的对象和 Scanner 对象。该方法的目的是启动机器人，让机器人承担一个任务方法(这里必须运行两个版本的doTask方法)，然后停止机器人。”

所以基本上它要求我创建多态方法并调用它两次，第一次将 EntertainmentRobot 传递给它，然后第二次 HumanStudyRobot。我不确定如何在测试器中进行设置，因为我在尝试编写代码时刚刚收到错误。我对多态方法/多态性也不太熟悉。

如有任何帮助，我们将不胜感激!

package Program;

import java.util.Scanner;

public abstract class Robot {

    //instance variables
    protected double EnergyUnitsRequired;
    protected double height;
    protected String manufacturer;
    protected String name;
    protected String purpose;
    protected double weight;
    protected double energy;

    //constructor
    public Robot(String name, double height, double weight, String manufacturer) {
        super();
        this.EnergyUnitsRequired = 0.25;
        this.height = height;
        this.manufacturer = manufacturer;
        this.name = name;
        this.purpose = "The robot's purpose needs to be provided";
        this.weight = weight;
        this.energy = 0.0;
    }

    //accessors & mutators
    public double getEnergyUnitsRequired() {
        return EnergyUnitsRequired;
    }

    public double getHeight() {
        return height;
    }

    public String getManufacturer() {
        return manufacturer;
    }

    public String getName() {
        return name;
    }

    public String getPurpose() {
        return purpose;
    }

    public double getWeight() {
        return weight;
    }

    public double getEnergy() {
        return energy;
    }

    public void setEnergyUnitsRequired(double energyUnitsRequired) {
        EnergyUnitsRequired = energyUnitsRequired;
    }

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

    public void setManufacturer(String manufacturer) {
        this.manufacturer = manufacturer;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPurpose(String purpose) {
        this.purpose = purpose;
    }

    public void setWeight(double weight) {
        this.weight = weight;
    }

    //methods
    public abstract void start();
    public abstract void stop();
    public abstract void doTask();
    public abstract void doTask(Scanner input);

    public void energyConsumption() {
        System.out.println("The robot: " + getName() + " has: " + getEnergy() + " to begin with.");
        double priorEnergy = getEnergy();
        energy = energy - energyRequired(); //the variable energyRequired should be returned from the energyRequired method below this method.
        System.out.println("My energy has depleted by the following amount: " + (priorEnergy - energy) + " units.");
        System.out.println("My energy is now at: " + energy + " units.");
    }

    public double energyRequired() {
        double energyRequired = (EnergyUnitsRequired * weight);
        return energyRequired;
    }

    public void regenerate() {
        energy = getEnergy() + (getWeight() * 2);
        System.out.println("More energy is being generated for the robot.");
    }
}

package Program;

import java.util.Scanner;

public class HumanStudyRobot extends Robot {

    //instance variables

    public HumanStudyRobot(String name, double height, double weight, String manufacturer) {
        super(name, height, weight, manufacturer);
        this.energy = 30.0;
    }

    @Override
    public void start() {
        System.out.println("This is a Human Study Robot");
        System.out.println("The robot has started studying.");
    }

    @Override
    public void stop() {
        System.out.println("The robot has finished studying.");
    }

    @Override
    public void doTask() {
    study();

    }

    @Override
    public void doTask(Scanner input) {
        // TODO Auto-generated method stub

    }

    public void study() {
    if (energy >= energyRequired()) {
        energyConsumption();
    }
    else 
        if (energy < energyRequired()) {
            System.out.println("The robot does not have sufficient energy.");
            regenerate();
            System.out.println("................");
            System.out.println("The robot has finished regenerating");
        }
    }


    public String toString() {
        return "I AM A HUMAN STUDY ROBOT : \nThe details of the entertainment robot are below:\n"
                + "Name : " + getName() + "\nWeight: " + getWeight() + "\nHeight: "
                + getHeight() + "\nManufacturer : " + getManufacturer() + "\nPurpose : "
                + getPurpose();
    }



}

package Program;

import java.util.Scanner;

import org.omg.Messaging.SyncScopeHelper;

public class EntertainmentRobot extends Robot {

    //constructor
    public EntertainmentRobot(String name, double height, double weight, String manufacturer) {
        super(name, height, weight, manufacturer);
        this.energy = 10.0;
        this.EnergyUnitsRequired = 0.75;
    }

    @Override
    public void start() {
        System.out.println("This is an Entertainment Robot. \n The robot has started entertaining.");
    }

    @Override
    public void stop() {
        System.out.println("The Entertainment RObot has finsihed entertaining");
    }

    @Override
    public void doTask() {

    }

    @Override
    public void doTask(Scanner input) {
        play();
    }

    public void talk() {

    }

    public void play () {
        System.out.println("How many times would you like to play?");
        if (getEnergy() >= energyRequired() ) {
            energyConsumption();
        }
        else 
            if (getEnergy() < energyRequired()) {
                System.out.println("The robot does not have sufficient energy to play.");
                regenerate();
                System.out.println("The robot is regenerating");
                System.out.println(".........................");
                System.out.println("The robot has finished regenerating!");
            }
    }

    public String toString() {
        return "\nI AM AN ENTERTAINMENT ROBOT \nThe details of the entertainment robot are below: \n" + 
                "Name : " + getName() + "\nHeight: " + getHeight() + "\nWeight: " + getWeight() + "\nManufacturer: " + 
                getManufacturer() + "\nPurpose: " + getPurpose();
    }

}


package Program;

import java.util.Scanner;

public class Tester02 {

    public static void main(String[] args) {

        HumanStudyRobot HumanStudyRobot1 = new HumanStudyRobot("HRP", 1.5, 58.0, "Kawada Industries");
        HumanStudyRobot1.setPurpose("Study into human movement and perform a wide range of tasks.");
/*      
        System.out.println(HumanStudyRobot1.toString());

        HumanStudyRobot1.start();
        HumanStudyRobot1.study();
        HumanStudyRobot1.stop();*/

        public void startRobot(Robot, Scanner input){

        }


        EntertainmentRobot EntertainmentRobot1 = new EntertainmentRobot("QRIO", 0.6, 7.3, "SONY");
        EntertainmentRobot1.setPurpose("To live with you, make life fun and make you happy.");

        System.out.println(HumanStudyRobot1.toString());
        System.out.println(EntertainmentRobot1.toString());
    }

}

Answer 1

第一次观察:您的 startRobot 方法签名无效，请将其更改为

public void startRobot(Robot robot, Scanner input){

}

第二个观察:将方法声明移到主方法之外。

第三个观察结果:使用机器人和扫描仪参数从主方法调用 startRobot。

startRobot(EntertainmentRobot1, /*your scanner*/);
startRobot(HumanStudyRobot1, /*your scanner*/);

由于这两个类都扩展了 Robot 类 - 它们可以传递给 startRobot 方法。有关此主题的更多阅读，请参阅 Oracle Documentation .