Java基础之：OOP——多态练习题

Java基础之：OOP——多态练习题

应用案例1：

编写教师类

要求有属性“姓名name”，“年龄age”，“职称post”，“基本工资salary”

编写业务方法， introduce（），实现输出一个教师的信息。

编写教师类的三个子类：教授类(professor)、副教授类(vice professor)、讲师类(lecturer)。

工资级别分别为：教授为1.3、副教授为1.2、讲师类1.1。在三个子类里面都重写父类的introduce（）方法。

定义并初始化一个老师对象，调用业务方法，实现对象基本信息的后台打印。

 

package polymorphic_HomeWork;

public class WorkTest_01 {

	public static void main(String[] args) {
		Teacher professor = new Professor("小范",20,"professor",4000.0);
		Teacher viceProfessor = new ViceProfessor("小黄",18,"ViceProfessor",3000.0);
		Teacher lecturer = new Lecturer("小雨",19,"lecturer",2000.0);
		
		System.out.println(professor.introduce());
		System.out.println(viceProfessor.introduce());
		System.out.println(lecturer.introduce());
	}

}

//要求有属性“姓名name”，“年龄age”，“职称post”，“基本工资salary”，
//编写业务方法， introduce（），实现输出一个教师的信息。
class Teacher{
	
	private String name;
	private int age;
	private String post;
	private double salary;
	public Teacher(String name, int age, String post, double salary) {
		super();
		this.name = name;
		this.age = age;
		this.post = post;
		this.salary = salary;
	}
	public Teacher() {
		super();
	}
	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 String getPost() {
		return post;
	}
	public void setPost(String post) {
		this.post = post;
	}
	public double getSalary() {
		return salary;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}
	
	//introduce（），实现输出一个教师的信息。
	public String introduce() {
		return "Teacher [name=" + name + ", age=" + age + ", post=" + post ;
	}
	
}

//教授类(professor)
class Professor extends Teacher{
	
	private double level;

	public Professor(String name, int age, String post, double salary) {
		super(name, age, post, salary);
		this.level = 1.3;
	}

	public double getLevel() {
		return level;
	}

	public void setLevel(double level) {
		this.level = level;
	}
	
	@Override
	public String introduce() {
		// TODO Auto-generated method stub
		return "Professor  " + super.introduce() + ", salary=" + getSalary()*level + "]";
	}
}

//副教授类（vice professor）
class ViceProfessor extends Teacher{
	
	private double level;

	public ViceProfessor(String name, int age, String post, double salary) {
		super(name, age, post, salary);
		this.level = 1.2;
	}

	public double getLevel() {
		return level;
	}

	public void setLevel(double level) {
		this.level = level;
	}
	
	@Override
	public String introduce() {
		// TODO Auto-generated method stub
		return "ViceProfessor  " + super.introduce()  + ", salary=" + getSalary()*level + "]";
	}
}

//讲师类（lecturer）
class Lecturer extends Teacher{
	
	private double level;

	public Lecturer(String name, int age, String post, double salary) {
		super(name, age, post, salary);
		this.level = 1.1;
	}

	public double getLevel() {
		return level;
	}

	public void setLevel(double level) {
		this.level = level;
	}
	
	@Override
	public String introduce() {
		// TODO Auto-generated method stub
		return "Lecturer  " + super.introduce()  + ", salary=" + getSalary()*level + "]";
	}
}

　　

应用案例2：

设计父类—员工类。子类：工人类(Worker),农民类(Peasant),教师类(Teacher),科学家类(Scientist),服务生类(Waiter)。

（1） 其中工人,农民,服务生只有基本工资。

（2） 教师除基本工资外,还有课酬(元/天)。

（3） 科学家除基本工资外,还有年终奖(bonus)。

（4） 编写一个测试类,将各种类型的员工的全年工资打印出来。

package polymorphic_HomeWork;
public class WorkTest_02 {

	public static void main(String[] args) {

		Employee worker = new Worker("工人 小范",20,2000);
		Employee peasant = new Peasant("农民 小范",40,1000);
		Employee waiter = new Waiter("服务生 小范",25,3000);
		Employee teacher = new Teacher("老师 小范",30,4000,50,200);
		Employee Scientist = new Scientist("科学家 小范",35,3500,250000);
		//这里创建的对象的编译类型都是Employee
		
//		System.out.println(worker.toString()); 
//		System.out.println(peasant.toString()); 
//		System.out.println(waiter.toString()); 
//		System.out.println(teacher.toString()); 
//		System.out.println(Scientist.toString()); 
		
		WorkTest_02 wt = new WorkTest_02();
		
		wt.showAll(Scientist);
		wt.showAll(teacher);
		wt.showAll(waiter);
		wt.showAll(peasant);
		wt.showAll(worker);
	}
	
	
	public void showAll(Employee e) {	//当有对象传入时，它的编译类型就变为了Employee。
		//由于子类重写了父类的show方法，而这里e的运行类型是动态绑定了的。
		//所以会自动的寻找到传入类型所对应的show方法
		//父类的show方法，相当于让编译器可以通过编译。如果父类中没有show方法会报语法错误。
		//因为e的编译类型为Employee.
		e.show();
	}

}

class Employee{
	private String name;
	private int age;
	private double salary;
	
	public Employee(String name, int age, double salary) {
		super();
		this.name = name;
		this.age = age;
		this.salary = salary;
	}
	public Employee() {
		super();
	}
	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 getSalary() {
		return salary;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}

	public void show() {	
		System.out.println(toString());
	}
	
	
	
	@Override
	public String toString() {
		return "name=" + name + ", age=" + age;
	}
	//提供一个方法返回基本年薪，子类可以在此基础上进行修改
	public double yearSalary() {
		
		return salary * 12;
	}
	
}

//工人类(Worker)
class Worker extends Employee{
	
	public Worker(String name, int age, double salary){
		super(name,age,salary);
	}
	
	@Override
	public void show() {
		System.out.println("Worker : " + super.toString() + ", salary: " + yearSalary()); 
	}
}

//农民类(peasant)
class Peasant extends Employee{
	
	public Peasant(String name, int age, double salary){
		super(name,age,salary);
	}
	
	@Override
	public void show() {
		System.out.println("Peasant : " + super.toString() + ", salary: " + yearSalary());
	}
}

//服务生类(waiter)
class Waiter extends Employee{
	
	public Waiter(String name, int age, double salary){
		super(name,age,salary);
	}
	
	@Override
	public void show() {
		System.out.println("Waiter : " + super.toString() + ", salary: " + yearSalary());
	}
}

//教师类(teacher),教师除基本工资外,还有课酬(元/天)。
class Teacher extends Employee{
	
	private double dollars;	//课酬
	private int workDays;	//工作天数
	

	public Teacher(String name, int age, double salary, double dollars, int workDays) {
		super(name, age, salary);
		this.dollars = dollars;
		this.workDays = workDays;
	}
	
	
	public int getWorkDays() {
		return workDays;
	}


	public void setWorkDays(int workDays) {
		this.workDays = workDays;
	}


	public double getDollars() {
		return dollars;
	}

	public void setDollars(double dollars) {
		this.dollars = dollars;
	}

	@Override
	public void show() {	
		System.out.println( "Teacher : " + super.toString() + 
				", salary: " + (yearSalary()+dollars*workDays));
	} 
	
}

//科学家类(scientist),	科学家除基本工资外,还有年终奖(bonus)。
class Scientist extends Employee{
	
	private double bonus;

	public Scientist(String name, int age, double salary, double bonus) {
		super(name, age, salary);
		this.bonus = bonus;
	}

	public double getBonus() {
		return bonus;
	}

	public void setBonus(double bonus) {
		this.bonus = bonus;
	}
	
	@Override
	public void show() {
		
		System.out.println("Scientist : " + super.toString() + 
				",salary:" + (yearSalary()+bonus)); 
	}
}

　　

 

应用案例3：

定义一个图形类Picture，再定义Picture的两个子类：圆形类Circle、矩形类Rect。 要求： 图像类：有求周长和求面积和显示图形信息的功能。 圆形类：包含圆心和半径，重写求周长和求面积的方法。 矩形类：包含长和宽，重写求周长和求面积的方法。

package polymorphic_HomeWork;

public class WorkTest_03 {

	public static void main(String[] args) {
		Picture circle = new Circle("2,2",3.1);
		Picture rect = new Rect(6.4,5.3);
		
		circle.show();
		rect.show();
	}

}

//图像类：有求周长和求面积和显示图形信息的功能。
class Picture{
	
	private double sideLength;	//边长
	private int sideCount;	//边数
	public Picture(double sideLength, int sideCount) {
		super();
		this.sideLength = sideLength;
		this.sideCount = sideCount;
	}
	public Picture() {
		super();
	}
	public double getSideLength() {
		return sideLength;
	}
	public void setSideLength(double sideLength) {
		this.sideLength = sideLength;
	}
	public int getSideCount() {
		return sideCount;
	}
	public void setSideCount(int sideCount) {
		this.sideCount = sideCount;
	}
	
	public double perimeter(){	//求周长
		return sideCount * sideLength;
	}
	
	public double area() {	//求面积
		
		return 0.0;
	}
	
	public void show() {
		
		System.out.printf("周长(perimeter)：%.2f	面积(area):%.2f
",perimeter(),area());
	}
}

//圆形类Circle：包含圆心和半径，重写求周长和求面积的方法。
class Circle extends Picture{
	private String centerCircle; //圆心:"X,Y" 
	private double radius;	//半径
	
	public Circle(String centerCircle, double radius) {
		super();
		this.centerCircle = centerCircle;
		this.radius = radius;
	}

	public String getCenterCircle() {
		return centerCircle;
	}

	public void setCenterCircle(String centerCircle) {
		this.centerCircle = centerCircle;
	}

	public double getRadius() {
		return radius;
	}

	public void setRadius(double radius) {
		this.radius = radius;
	}
	
	@Override
	public double perimeter(){	//求周长
		return 2 * radius * Math.PI;
	}
	
	@Override
	public double area() {	//求面积
		return radius * radius * Math.PI;
	}
	
	@Override
	public void show() {
		System.out.printf("Circle：圆心为 ：%S  ",centerCircle);
		super.show();
	}
}

//矩形类Rect：包含长和宽，重写求周长和求面积的方法。
class Rect extends Picture{
	private double length;//长
	private double wide;//宽
	public Rect( double length, double wide) {
		super();
		this.length = length;
		this.wide = wide;
	}
	public double getLength() {
		return length;
	}
	public void setLength(double length) {
		this.length = length;
	}
	public double getWide() {
		return wide;
	}
	public void setWide(double wide) {
		this.wide = wide;
	}
	
	@Override
	public double perimeter(){	//求周长
		return 2 * length + 2 * wide;
	}
	
	@Override
	public double area() {	//求面积
		return length * wide;
	}
	
	@Override
	public void show() {
		System.out.print("Rect：  ");
		super.show();
	}
}