JAVA语言程序设计（基础篇） 第十版——第11章 继承和多态 （参考答案）

编程练习题

（11.2~11.4节）+（11.5~11.14节）

11.1（三角形Triangle）

父类（左边） 和   子类（右边）继承关系，

如下图： 

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---

package p11;

public class GeometricObject {
	private String color = "white";
	private boolean filled;
	private java.util.Date dateCreated;
	
	public GeometricObject() {
		dateCreated=new java.util.Date();
	}
	
	public GeometricObject(String color, boolean filled) {
		dateCreated=new java.util.Date();
		this.color=color;
		this.filled=filled;
	}
	
	public String getColor() {
		return color;
	
	}
	
	public void setColor(String color) {
		this.color=color;
	}
	
	public boolean isFilled() {
		return filled;
	
	}
	
	public void setFilled(boolean filled) {
		this.filled=filled;
	
	}
	
	public java.util.Date getDateCreated() {
		return dateCreated;
	
	}
	
	public String toString() {
		return "created on " + dateCreated + "\ncolor: " + color+   
				" and filled: " + filled;
	
	}
}

 

package p11;

public class Triangle extends GeometricObject {
	private double side1 = 1.0;
	private double side2 = 1.0;
	private double side3 = 1.0;
	
	public Triangle() {
		
	}
	
	//这是一个 重载 的构造方法
	public Triangle(double side1, double side2,
			double side3, String color, boolean filled) {   
		
		super(color,filled);//或者 调用父类中已有方法 ,如下
							//setColor(color);
		                   //setFilled(filled);
		this.side1=side1;
		this.side2=side2;
		this.side3=side3;
		
	}
	
	public double getSide1() {
		return side1;
	
	}
	
	public double getSide2() {
		return side2;
	
	}
	
	public double getSide3() {
		return side3;
	
	}
	
	public double getArea() {
		double s=(side1+side2+side3)/2;
		double area=Math.pow( s*(s-side1)*(s-side2)*(s-side3) , 0.5); 
		return area;
	}
	
	public double getPerimeter() {
		return side1+side2+side3;
	
	}
	
	@Override
	public String toString() {
	
		return super.toString() + "\nArea is " + getArea();
	
	}
}

package p11;

import java.util.Scanner;

public class Test1 {

	public static void main(String[] args) {
		Scanner input=new Scanner(System.in);
		System.out.print("请输入三角形的三条边：");
		double s1=input.nextInt();
		double s2=input.nextInt();
		double s3=input.nextInt();
		
		System.out.print("请输入三角形的颜色: ");
		String c1=input.next();
		
		System.out.print("请输入一个boolean值(false:不填充；true：填充)：");   
		boolean f1=input.nextBoolean();
		
		input.close();
		
		//创建对象
		GeometricObject object=new Triangle(s1, s2, s3, c1, f1);
		
		System.out.println(object.toString());
		
		
		
	}

}

 

（11.5~11.14节）

11.2（Person、Student、Employee、Faculty 和 Staff类）

这个不难，我也就是在 受聘日期 那里“卡壳”了一下

总体的继承关系：

---

 

package p11;

public class Person {
	private String name;
	private String adress;
	private String phone;
	private String email;
	
	public Person(String name, String adress, String phone, String email) {
		this.name=name;
		this.adress=adress;
		this.phone=phone;
		this.email=email;
	}
	
	public Person(String name) {
		this.name=name;
	}
	
	public String getAdress() {
		return adress;
	
	}
	
	public void setAdress(String adress) {
		this.adress=adress;
	}
	
	public String getPhone() {
		return phone;
	
	}
	
	public void setPhone(String phone) {
		this.phone=phone;
	}
	
	public String getEmail() {
		return email;
	
	}
	
	public void setEmail(String email) {
		this.email=email;
		
	}
	
	public String toString() {
		return "The Person's name is "+name+"\nAdress is "+adress+
				"\nPhone is "+phone+"\nEmail is "+email;
	
	}
}

package p11;

public class Student extends Person {
	
	private int classState;
	
	public final static int FRESHMAN=1;//大一新生
	public final static int SOPHOMORE=2;//大二学生
	public final static int JUNIOR=3;//大三学生
	public final static int SENIOR=4;//大四学生
	
	
	public Student(int classState, String name, String adress, String phone, String email) {
		super(name, adress, phone, email);
		this.classState=classState;
		
	}
	
	public int getClassState() {
		return classState;
	
	}
	
	public void setClassState(int classState) {
		this.classState=classState;
	}
	
	@Override
	public String toString() {
		return "The Student's classState is "+classState+"\n"+super.toString();
	
	}
}

package p11;

import java.util.Date;

import p10.MyDate;

public class Employee extends Person {
	
	private String office;
	private double salary;
	private MyDate DateOfAppointment;//受聘日期
	
	//构造方法
	public Employee(String office, double salary, MyDate DateOfAppointment, 
			String name, String adress, String phone, String email) {
		
		super(name, adress, phone, email);
		
		this.DateOfAppointment=DateOfAppointment;
		this.salary=salary;
		this.office=office;
		
	}
	
	public String getOffice() {
		return office;
	
	}
	
	public void setOffice(String office) {
		this.office=office;
	}
	
	public double getSalary() {
		return salary;
	
	}
	
	public void setSalary(double salary) {
		this.salary=salary;
	}
	
	public String getDateOfAppointment() {
		
		return DateOfAppointment.getYear()+"年"+DateOfAppointment.getMonth()
			+"月"+DateOfAppointment.getDay()+"日";
	
	}
	
	@Override
	public String toString() {
		return "The Employee's dateOfAppointment is "+  getDateOfAppointment()
								+"\nOffice is "+office+"\nSalary is "+salary+"\n"+super.toString();
	
	}
}

package p11;

import p10.MyDate;

public class Faculty extends Employee {
	private long officeHours;
	private String rank;
	
	//构造方法
	public Faculty(long officeHours, String rank, String office, double salary, MyDate DateOfAppointment,
			String name, String adress, String phone, String email) {
		
		super(office, salary, DateOfAppointment, name, adress, phone, email);
		this.officeHours=officeHours;
		this.rank=rank;
	}
	
	public long getOfficeHours() {
		return officeHours;
	
	}
	
	public void setOfficeHours(long officeHours) {
		this.officeHours=officeHours;
	}
	
	public String getRank() {
		return rank;
	
	}
	
	public void setRank(String rank) {
		this.rank=rank;
	}
	
	@Override
	public String toString() {
		return "The Faculty's officeHours is "+officeHours+"\nRank is "+rank+
				"\n"+super.toString();
	
	}
}

package p11;

import p10.MyDate;

public class Staff extends Employee {
	
	private String title;
	
	//构造方法
	public Staff(String title, String office, double salary, MyDate DateOfAppointment, String name, 
			String adress, String phone, String email) {
	
		super(office, salary, DateOfAppointment, name, adress, phone, email);
		this.title=title;
	}
	
	public String getTitle() {
		return title;
	
	}
	
	public void setTitle(String title) {
		this.title=title;
	}
	
	@Override
	public String toString() {
		return "The Staff's title is "+title+"\n"+super.toString();
	
	}
}

package p11;

import p10.MyDate;

public class Test2 {

	public static void main(String[] args) {
		
		Person person=new Person("王大狗","垃圾堆","123456789","[email protected]");  
		
		Person student=new Student(4,"王大狗","垃圾堆","123456789","[email protected]"); 
		
		Person employee=new Employee("五星街办公室一号",5600,new MyDate(1996,12,17),"王大狗","垃圾堆","123456789","[email protected]");

		Person faculty=new Faculty(8, "二等", "五星街办公室一号",5600,new MyDate(1996,12,17),"王大狗","垃圾堆","123456789","[email protected]");
		
		Person staff=new Staff("优秀员工","五星街办公室一号",5600,new MyDate(1996,12,17),"王大狗","垃圾堆","123456789","[email protected]");
		
		
		System.out.println(person.toString());
		System.out.println();
		System.out.println(student.toString());
		System.out.println();
		System.out.println(employee.toString());
		System.out.println();
		System.out.println(faculty.toString());
		System.out.println();
		System.out.println(staff.toString());
		
	}

}

---

 

11.3（账户类Account的子类）

  

1.我先解释一下下：
       透支限定额：也就是可以让你在卡没有钱的情况下还   可以借你最大的资金限额 ，透支额度是银行根据你提交的个人资料、财力证明等材料来综合评定的，一般是3000到5w不等。普卡最高在1w左右，金卡最高可以到5w甚至更高。

package p9;

import java.util.Date;

public class Account {
		
	public int id=0;//用户名
	public double balance=0;//余额
	public double annualInteresRate=0;//当前利率
	public java.util.Date dateCreated;//存储开户日期
	
	//无参构造方法
	public Account(){
		Date dateCreated=new Date();
		this.dateCreated=dateCreated;
	}
	
	//有参构造方法
	public Account(int id, double balance){
		Date dateCreated=new Date();
		this.dateCreated=dateCreated;
		this.id=id;
		this.balance=balance;
	}
	
	public int getId(){
		return id;
		
	}
	
	public double getBalance() {
		return balance;
	}
	
	
	public double getAnualInterestRate() {
		return annualInteresRate;
		
	}
	
	
	public void setId(int id){
		this.id=id;
	}
	
	
	public void setBalance(double balance) {
		this.balance=balance;
	}
	
	//设置 年利率
	public void setAnnualInterestRate(double annualInterestRate) {
		this.annualInteresRate=annualInterestRate;
	}

	//获得开户日期
	public String getDateCreated(){
		return dateCreated.toString();
		}
	
	//月利息
	public double getMonthlyInterestRate() {
		return annualInteresRate/12;
		
	}
	
	//取钱
	public double withDraw(double withdraw) {
		return this.balance=this.balance-withdraw;
	}
	
	//存钱
	public double deposit(double deposit) {
		return this.balance=this.balance+deposit;
	}

	
}

package p11;

import p9.Account;

public class CheckingAccount extends Account{
	
	private double OverDraftLimit;//限定透支额度
	
	public CheckingAccount(int id, double balance, double OverdraftLimit) {
		
		super(id, balance);
		
		this.OverDraftLimit=OverDraftLimit;//可用额度
	}
	
	//
	public double getOverDraftLimit() {
		return OverDraftLimit;
	}
	
	public void setOverDraftLimit(double OverDraftLimit) {
		this.OverDraftLimit=OverDraftLimit;
	}
	
	@Override
	//取钱
	public double withDraw(double withdraw) {
		
		//可用额度不为0时
		if(getOverDraftLimit() != 0) {
			
			//自动提款机，小于100元不提取
			if(this.balance<100) {
				
			//移用,“可用额度”
			this.balance = this.balance + this.OverDraftLimit;
			
			//移用,“可用额度”后,系统自动将可用额度 “清零”,以后的可用额度就为 "0"
			setOverDraftLimit(0);
			
			return this.balance=this.balance-withdraw;
			}
			else {
				//正常卡里有钱并且>100元时，不用 “可用额度”
				return this.balance=this.balance-withdraw;
			}
			
		}   
		//当可用额度为0时
		else if(getOverDraftLimit() == 0){
			if(this.balance<100) {
				return -1;//返回一个负数，表示不可取钱了！！！
			}
			else {
				//正常卡里有钱并且>100元时，不用 “可用额度”
				return this.balance=this.balance-withdraw;
			}
		}
		
		return this.balance;
	}
				
	public String toString() {
		return "The ID:"+id+"\nThe balance is "
					+balance+"\n可用额度为："+getOverDraftLimit();
	
	}
}

 

package p11;

import p9.Account;

public class SavingAccount extends Account{
	
	public SavingAccount(int id, double balance) {
		super(id,balance);
	}
	
	@Override   //取钱方法 不可透支
	public double withDraw(double withdraw) {
		//自动提款机 <100 元是不能够取出来的，我这里用-1表示
		if(this.balance<100) {
			return -1;
		}
		else {
			return this.balance=this.balance-withdraw;
		}
	}
	
	public String toString() {
		return "The ID:"+id+"\nThe balance is "
				+balance;
	
	}
}

 

11.4（ArrayList 的最大元素）

package p11;

import java.util.ArrayList;
import java.util.Scanner;

public class Test4 {

	public static void main(String[] args) {
		Scanner input=new Scanner(System.in);
		System.out.println("请输入一个以0结尾的数值序列：");
		
		//创建一个数组列表:该ArrayList对象可以用于存储 Integer整型数值    
		ArrayList list=new ArrayList<>();
		
		int value=input.nextInt();
		
		while(value != 0) {
			
			list.add(value);
			value=input.nextInt();
		}
		
		input.close();
		
		//调用max方法，来返回输入的最大值
		System.out.println("最大值是："+max(list));
		
	}

	//一个返回数组列表中最大值的方法
	public static Integer max(ArrayList list) {
		if(list.isEmpty() || list.size()==0) {
			return null;
		}
		else {
			int max=list.get(0);
			int maxIndex=0;
			
			for(int i=1; i

11.5（课程类 Course）

package p11;

import java.util.ArrayList;

public class Course {
	
	private String courseName;
	
	//用数组列表存储学生名
	private ArrayList students = new ArrayList<>();
	
	private int numberOfStudents;
	
	//课程的一个构造方法
	public Course(String courseName) {
		this.courseName = courseName;
	}
	
	//返回课程名
	public String getCourseName() {
		return courseName;
	
	}
	
	//增加学生名字
	public void addStudent(String student) {
		students.add(student);
	}
	
	//删除学生名字
	public void dropStudent(String student) {
		students.remove(student);
	}
	
	//返回 学生名字列表
	public ArrayList getStudents() {
		return students;
	
	}
	
	//返回 学生人数
	public int getNumberOfStudents() {
		return numberOfStudents=students.size();
	
	}
}

package p11;

public class Test5 {

	public static void main(String[] args) {
		Course object1=new Course("Date Structures");
		Course object2=new Course("Date Systems");
		
		object1.addStudent("Peter Jones");
		object1.addStudent("Kim Smith");
		object1.addStudent("Anne Kennedy");
		
		object2.addStudent("Peter Jones");
		object2.addStudent("Steve Smith");
		
		System.out.println("Number of students in course1: "    
				+ object1.getNumberOfStudents());
		
		//输出 数组列表
		System.out.println(object1.getStudents());
	
		System.out.println("Number of students in course2: "
					+object2.getNumberOfStudents());   
		
	}

}

 

11.6（使用 ArrayList）

说明一下：我没有创建Loan类、Circle类，而是直接用我自己之前包里有的类来创建对象，其实用哪个类都是一样的。

package p11;

import java.util.ArrayList;
import java.util.Date;

public class Test6 {

	public static void main(String[] args) {
		
		ArrayList