【0基础学java】教学日志：javaSE-面向对象6-面向对象前4章上机作业点评，主要涉及继承、封装、多态三个章节的内容

一、面向对象第一章上机作业参考答案（略）
可参考课堂Demo进行编写
链接地址：https://www.cnblogs.com/yppjava/p/15690472.html
二、面向对象第二章上机作业参考答案：
1、上机练习1——设计Dog和Penguin类

• 需求说明：
  – 运用面向对象思想抽象出Dog类和Penguin类，画出对应类图

​

编辑

切换为居中
添加图片注释，不超过 140 字（可选）

– 根据类图编写Dog类和Penguin类
– 添加默认构造方法
2、上机练习2——打印Dog信息2-1

• 需求说明：
  – 根据控制台提示信息选择领养宠物（狗），
  ▪ 输入昵称、品种、健康值
  ▪ 打印宠物信息
  – 要保证健康值的有效性（在1到100之间）
  3、上机练习3——Dog类的带参构造方法
• 需求说明：
  – 增加带参构造方法
  ​Dog(String name, String strain)
  – 修改Test类，使用带参构造方法创建对象
  4、上机练习4——操作企鹅性别属性
• 需求说明：
  – 给Penguin类提供SEX_MALE和SEX_FEMALE两个静态常量，分别取值“Q仔”或“Q妹”
  – 修改Test类，使用静态常量对性别进行赋值
  – 修改企鹅的性别只能取值“雄”或“雌”，通过修改静态变量实现该需求
  参考：
  Dog.java
  package netclass05.homework2;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 15:42

• @Description: netclass05.homework2

• @version: 1.0
  */
  public class Dog {

  //昵称
  private String name;

  //健康值
  private int health;

  //亲密度
  private int love;

  //品种
  private String strain;

  public Dog(){

  }

  public Dog(String name, int health, String strain) {
  this.name = name;
  this.health = health;
  this.strain = strain;
  }

  public Dog(String name, int health, int love, String strain) {
  this.name = name;
  this.health = health;
  this.love = love;
  this.strain = strain;
  }

  public String getName() {
  return name;
  }

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

  public int getHealth() {
  return health;
  }

  public void setHealth(int health) {
  if(health >= 1 &&health <= 100){
  this.health = health;
  }else{
  System.out.println("你输入的健康值有误，请重新输入。");
  }

  }

  public int getLove() {
  return love;
  }

  public void setLove(int love) {
  this.love = love;
  }

  public String getStrain() {
  return strain;
  }

  public void setStrain(String strain) {
  this.strain = strain;
  }

  // 输出信息
  public void print(){
  System.out.println("狗的昵称是：" +this.name + ",健康值：" +this.health + ",亲密度：" + this.love + ",品种是：" + this.strain);
  }

}

Penguin.java
package netclass05.homework2;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 15:47

• @Description: netclass05.homework2

• @version: 1.0
  */
  public class Penguin {

  //昵称
  private String name;

  //健康值
  private int health;

  //亲密度
  private int love;

  //性别
  private static String gender;

  //添加静态常量
  static final String SEX_MALE = "Q仔";

  static final String SEX_FEMALE = "Q妹";

  public Penguin() {
  }

  public Penguin(String name, int health, int love, String gender) {
  this.name = name;
  this.health = health;
  this.love = love;
  this.gender = gender;
  }

  public String getName() {
  return name;
  }

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

  public int getHealth() {
  return health;
  }

  public void setHealth(int health) {
  if(health >= 1 &&health <= 100){
  this.health = health;
  }else{
  System.out.println("你输入的健康值有误，请重新输入。");
  }
  }

  public int getLove() {
  return love;
  }

  public void setLove(int love) {
  this.love = love;
  }

  public String getGender() {
  return gender;
  }

  public void setGender(String gender) {
  if("雄".equals(gender)){
  this.gender = "雄";
  }else if("雌".equals(gender)){
  this.gender = "雌";
  }else{
  System.out.println("您输入的性别有误，请重新输入！");
  }
  // this.gender = gender;
  }

  //输出方法
  public void print(){
  System.out.println("企鹅的昵称是：" +this.name + ",健康值：" +this.health + ",亲密度：" + this.love + ",性别是：" + this.gender);

  }

  public static void main(String[] args) {
  // Penguin p = new Penguin("小黑",10,20,"雄性");
  // Penguin p = new Penguin();
  // p.setName("小白");
  // p.setHealth(10);
  // p.setLove(20);
  // p.setGender("雄性");
  // System.out.println(p.getName());
  // p.print();
  // 创建
  }
  }

TestDemo.java
package netclass05.homework2;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 16:32

• @Description: netclass05.homework2

• @version: 1.0
  */
  public class TestDemo {

  public static void main(String[] args) {
  // //创建Scanner对象，接收键盘输入
  // Scanner scanner = new Scanner(System.in);
  // //读取昵称
  // System.out.print("请输入狗的昵称：");
  // String name = scanner.next();
  // //读取品种
  // System.out.print("请输入狗的品种：");
  // String strain = scanner.next();
  // //读取健康值
  // System.out.print("请输入狗的健康值：");
  // int health = scanner.nextInt();
  //创建狗对象
  // Dog dog = new Dog();
  // dog.setName(name);
  // dog.setStrain(strain);
  // dog.setHealth(health);
  // Dog dog = new Dog(name,health,strain);
  // dog.print();

   Penguin p = new Penguin();
   p.setName("小白");
   p.setHealth(30);
  

// p.setGender(Penguin.SEX_MALE);
p.setGender("雄性");
p.print();
}
}

三、面向对象第三章上机作业参考答案：
1、上机练习1已在第三章博客中编写，请参考；
链接地址：
【0基础学java】教学日志：javaSE-面向对象3-this关键字、static关键字、代码块、package、import、封装、访问修饰符
2、上机练习2
​
​

参考：
父类Animal.java
​package netclass05.homework3;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 15:21

• @Description: netclass05.homework3

• @version: 1.0
  */
  public abstract class Animal {

  //年龄
  private int age;

  public Animal(){

  }

  public Animal(int age){
  this.age = age;
  }

  public int getAge() {
  return age;
  }

  public void setAge(int age) {
  this.age = age;
  }

  //自我介绍的抽象方法
  public abstract void introduce();

}

子类Fish.java
package netclass05.homework3;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 15:24

• @Description: netclass05.homework3

• @version: 1.0
  */
  public class Fish extends Animal {

  private int weight;

  public Fish(){

  }
  public Fish(int age,int weight){
  super(age);
  this.weight = weight;
  }

  public int getWeight() {
  return weight;
  }

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

  @Override
  public void introduce() {
  System.out.println("鱼的年龄是：" + super.getAge() + ",重量是：" + weight + "kg");
  }

  //子类特有的方法 游泳
  public void swim(){
  System.out.println("我是一条鱼，正在游泳呢... ...");
  }
  }

子类Bird.java
package netclass05.homework3;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 15:27

• @Description: netclass05.homework3

• @version: 1.0
  */
  public class Bird extends Animal{
  private String color;

  public Bird(){

  }
  public Bird(int age,String color){
  super(age);
  this.color = color;
  }

  public void setColor(String color){
  this.color = color;
  }

  public String getColor(){
  return color;
  }

  @Override
  public void introduce() {
  System.out.println("鸟的年龄：" + super.getAge() +",颜色是：" +color);
  }

  //子类特有的方法 飞
  public void fly(){
  System.out.println("我是一只鸟，我正在飞... ...");
  }
  }

测试类AnimalTest.java
package netclass05.homework3;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 15:30

• @Description: netclass05.homework3

• @version: 1.0
  */
  public class AnimalTest {

  public static void main(String[] args) {
  Fish fish = new Fish(17,2);
  fish.introduce();
  fish.swim();
  Bird bird = new Bird(16,"彩色");
  bird.introduce();
  bird.fly();
  }
  }

​
四、面向对象第四章作业参考答案：
1、上机练习—使用多态实现主人领养宠物并与宠物玩耍
需求说明：
– 主人根据宠物编号领养宠物
– 主人和狗狗玩接飞盘游戏，狗狗健康值减少10，不主人亲密度增加5
– 主人和企鹅玩游泳游戏，企鹅健康值减少10，不主人亲密度增加5
2、上机练习——计算一次租赁多辆汽车的总租金
​

3、上机练习——购置新车
​

参考：
机动车类 MotoVehical.java
​
package netclass04.abstracts.homework;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/12 - 01 - 12 - 16:23

• @Description: netclass04.abstracts.homework

• @version: 1.0
  */
  public abstract class MotoVehical {

  private String no;
  private String brand;

  public MotoVehical(){

  }

  public MotoVehical(String no, String brand) {
  this.no = no;
  this.brand = brand;
  }

  public String getNo() {
  return no;
  }

  public void setNo(String no) {
  this.no = no;
  }

  public String getBrand() {
  return brand;
  }

  public void setBrand(String brand) {
  this.brand = brand;
  }

  //抽象方法（根据天数计算租金）
  public abstract int calcRent(int days);

}

轿车类 Car.java
package netclass04.abstracts.homework;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/12 - 01 - 12 - 16:25

• @Description: netclass04.abstracts.homework

• @version: 1.0
  */
  public class Car extends MotoVehical {

  private String type;

  public Car(){

  }

  public Car(String no,String brand,String type){
  super(no,brand);
  this.type = type;
  }

  public String getType() {
  return type;
  }

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

  @Override
  public int calcRent(int days) {
  if(this.type.equals("0")){
  return 600 * days;
  }else if(this.type.equals("1")){
  return 500 * days;
  }else if(this.type.equals("2")){
  return 300 * days;
  }else{
  System.out.println("您输入的车型不存在！");
  return 0;
  }
  }
  }

客车类 Bus.java
package netclass04.abstracts.homework;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/12 - 01 - 12 - 16:28

• @Description: netclass04.abstracts.homework

• @version: 1.0
  */
  public class Bus extends MotoVehical {

  private int seatCount;

  public Bus(){

  }

  public Bus(String no,String brand,int seatCount){
  super(no,brand);
  this.seatCount = seatCount;
  }

  public int getSeatCount() {
  return seatCount;
  }

  public void setSeatCount(int seatCount) {
  this.seatCount = seatCount;
  }

  @Override
  public int calcRent(int days) {
  if(this.seatCount > 16){
  return 1500 * days;
  }else{
  return 800 * days;
  }
  }
  }

卡车类 Truck.java
package netclass04.abstracts.homework;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 14:50

• @Description: netclass04.abstracts.homework

• @version: 1.0
  */
  public class Truck extends MotoVehical {

  //吨位
  private int weight;

  public Truck(String no,String brand,int weight){
  super(no,brand);
  this.weight = weight;
  }

  @Override
  public int calcRent(int days) {
  return 50 * days * this.weight;
  }
  }

测试类 MotoVehicalTest.java
package netclass04.abstracts.homework;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/12 - 01 - 12 - 16:30

• @Description: netclass04.abstracts.homework

• @version: 1.0
  */
  public class MotoVehicalTest {

  public static void main(String[] args) {
  // MotoVehical moto = new MotoVehical();
  // Car car = new Car("豫A 8888888","别克","0");
  // int total1 = car.calcRent(5);
  // System.out.println("租金为：" +total1);
  // Bus bus = new Bus("豫A 6666666","金杯",16);
  // int total2 = bus.calcRent(5);
  // System.out.println("租金为：" +total2);
  MotoVehical[] motoArray = new MotoVehical[5];
  //String[] arrays = new String[4];
  motoArray[0] = new Car("豫A 00099999","宝马550i","1");
  motoArray[1] = new Car("豫B 00088888","宝马550i","1");
  motoArray[2] = new Car("豫C 00066666","别克林荫大道","2");
  motoArray[3] = new Bus("豫D 00011111","金龙",34);
  motoArray[4] = new Truck("豫E 000333333","东方红",50);
  // int totalRent = 0;
  // for(int i = 0; i<motoArray.length;i++){
  // totalRent += motoArray[i].calcRent(5);
  // }
  int totalRent = MotoVehicalTest.calcRent(motoArray,5);
  System.out.println("租5天的总租金是：" + totalRent);
  }

  public static int calcRent(MotoVehical[] motoArray,int days){
  int totalRent = 0;
  for(int i = 0; i<motoArray.length;i++){
  totalRent += motoArray[i].calcRent(days);
  }
  return totalRent;
  }
  }

五、答疑，主要是关于Object对象、抽象类的使用、instanceof的使用、向上转型和向下转型的理解。
1、Object对象的使用
package netclass05.demo;

import java.util.Objects;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 17:17

• @Description: netclass05

• @version: 1.0
  /
  public class ObjectTest /extends Object*/ {

  private String name;
  private int age;

  public ObjectTest(){
  // super();
  }

  public ObjectTest(String name,int age){
  this.name = name;
  this.age = age;
  }

  public String getName() {
  return name;
  }

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

  public int getAge() {
  return age;
  }

  public void setAge(int age) {
  this.age = age;
  }

  @Override
  public String toString() {
  return "ObjectTest{" +
  "name='" + name + ''' +
  ", age=" + age +
  '}';
  }

  @Override
  public boolean equals(Object o) {
  if (this == o) return true;
  if (o == null || getClass() != o.getClass()) return false;
  ObjectTest that = (ObjectTest) o;
  return age == that.age &&
  Objects.equals(name, that.name);
  }

  @Override
  public int hashCode() {
  return Objects.hash(name, age);
  }

  public static void main(String[] args) {
  // 需求：想打印出对象的内容
  ObjectTest ot = new ObjectTest("张飞",18);
  ObjectTest ot2 = new ObjectTest("张飞",18);
  System.out.println(ot);
  // System.out.println(ot == ot2);
  // System.out.println(ot.equals(ot2));
  // System.out.println(ot.getClass().getName());
  // System.out.print(ot);
  // ot.setName("张飞");
  // ot.setAge(18);
  // System.out.println(ot.getName());
  // System.out.println(ot.getAge());

   //instanceof的用法  ： 判断一个对象是否是某个类的实例
   if(ot instanceof ObjectTest){
       System.out.println("yes");
   }else{
       System.out.println("no");
   }
  

  }

}

2、instanceof的使用
package netclass05.demo;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 17:41

• @Description: netclass05.demo

• @version: 1.0
  */
  public class A {

  public void print(){
  System.out.println("我是A... ...");
  }
  }

package netclass05.demo;

/**

• @Auther: Yu Panpan

• @Date: 2022/1/14 - 01 - 14 - 17:41

• @Description: netclass05.demo

• @version: 1.0
  */
  public class B extends A {

  public void print(){
  System.out.println("我是B... ...");
  }

  public static void main(String[] args) {
  A a = new A();
  //向下转型
  B b = (B)a;
  b.print();
  }
  }

3、抽象类的使用、向上转型和向下转型的理解
父类 AbstractTest.java
package netclass05.demo;

/**

• @Auther: Yu Panpan
• @Date: 2022/1/14 - 01 - 14 - 17:31
• @Description: netclass05.demo
• @version: 1.0
  */

/**

• 定义一个人类
  */
  public abstract class AbstractTest {

  private String name;
  private int age;
  //基本工资
  private double basicSalary;

  public AbstractTest() {
  }

  public AbstractTest(String name, int age) {
  this.name = name;
  this.age = age;
  }

  public AbstractTest(String name, int age,double basicSalary) {
  this.name = name;
  this.age = age;
  this.basicSalary = basicSalary;
  }

  public String getName() {
  return name;
  }

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

  public int getAge() {
  return age;
  }

  public void setAge(int age) {
  this.age = age;
  }

  public double getBasicSalary() {
  return basicSalary;
  }

  public void setBasicSalary(double basicSalary) {
  this.basicSalary = basicSalary;
  }

  //定义一个计算工资的方法
  public abstract double getSalary();

}

子类 Worker.java
package netclass05.demo;

/**

• @Auther: Yu Panpan
• @Date: 2022/1/14 - 01 - 14 - 17:32
• @Description: netclass05.demo
• @version: 1.0
  */

/**

• 工人类
  */
  public class Worker extends AbstractTest {

  //绩效工资
  private double kpiSalary;

  public Worker(){

  }

  public Worker(String name,int age,double kpiSalary){
  super(name,age);
  this.kpiSalary = kpiSalary;
  }

  public double getKpiSalary() {
  return kpiSalary;
  }

  public void setKpiSalary(double kpiSalary) {
  this.kpiSalary = kpiSalary;
  }

  @Override
  public double getSalary() {
  //基本工资+绩效工资
  return super.getBasicSalary() + this.getKpiSalary();
  }

  public static void main(String[] args) {
  //向上转型：子类向父类转化，会自动转化
  AbstractTest at = new Worker();

   //向下转型：父类向子类转化，需要强制转化，而且可能会出现问题
  

// AbstractTest at2 = new AbstractTest();//错误的

}

}