Java抽象类、接口（例题及代码）

1．编写一个抽象类Shape，声明计算图形面积的抽象方法。再分别定义Shape的子类Circle（圆）和Rectangle（矩形），在两个子类中按照不同图形的面积计算公式，实现Shape类中计算面积的方法。

public abstract class Sharp {
	public abstract double area();

	public Sharp() {
	}
}

class Circle extends Sharp {
	private double r;

	public Circle() {
		super();
	}

	public double getR() {
		return r;
	}

	public void setR(double r) {
		this.r = r;
	}

	@Override
	public double area() {
		// TODO Auto-generated method stub
		return Math.PI * r * r;
	}
}

class Rectangle extends Sharp {
	private double a, b;

	public Rectangle() {
		super();
	}

	public double getA() {
		return a;
	}

	public void setA(double a) {
		this.a = a;
	}

	public double getB() {
		return b;
	}

	public void setB(double b) {
		this.b = b;
	}

	@Override
	public double area() {
		// TODO Auto-generated method stub
		return a * b;
	}
}

public class Test {

	public static void main(String[] args) {
		Circle c = new Circle();
		c.setR(2);
		System.out.println(c.area());
		Rectangle re = new Rectangle();
		re.setA(4);
		re.setB(5);
		System.out.println(re.area());
	}
}

2．创建一个接口IShape，接口中有一个求取面积的抽象方法“public double area()”。定义一个正方形类Square，该类实现了IShape接口。Square类中有一个属性a表示正方形的边长，在构造方法中初始化该边长。定义一个主类，在主类中，创建Square类的实例对象，求该正方形对象的面积。

public interface ISharp {
	double area();
}

public class Square implements ISharp {
	private double a;

	public Square() {
		super();
	}

	public Square(double a) {
		super();
		this.a = a;
	}

	public double getA() {
		return a;
	}

	public void setA(double a) {
		this.a = a;
	}

	@Override
	public double area() {
		// TODO Auto-generated method stub
		return a * a;
	}
}

public class Test {

	public static void main(String[] args) {
		Square s = new Square();
		s.setA(4);
		System.out.println(s.area());
	}
}

3.创建一个工人类Worker
（1）工人类的属性：工龄、工号、姓名、基本工资 Phone phone String str
需要定义一个Phone类，属性：brand price
（2）输出所有信息的方法（包含手机的信息）
（3）定义一个输出工资的方法（工资=基本工资）
（4）创建一个部门经理类，继承工人Worker类，并重写其计算工资的方法
（工资=基本工资+岗位级别 * 500+工龄*1000）
添加属性Saler saler; 定义一个方法manager(){打印部门经理谁负责管理的是哪个销售人员，当月的销售金额是XX} 表示管理哪个销售人员
（5）创建一个销售人员类，继承工人Worker类，
并增加一个属性（销售金额）。
并重写其计算工资的方法
（工资=基本工资+销售金额 * 系数（*其中系数当销售金额大于100W时为0.09，小于100W时为0.08））
（6）创建测试类，分别定义Manager类的对象，并赋值，调用其输出工资的方法和manager方法进行测试。

public class Worker {
	private int year;
	private int num;
	private String name;
	private double money;
	private Phone phone;

	public Worker() {
		super();
	}

	public Worker(int year, int num, String name, double money, Phone phone) {
		super();
		this.year = year;
		this.num = num;
		this.name = name;
		this.money = money;
		this.phone = phone;
	}

	public int getYear() {
		return year;
	}

	public void setYear(int year) {
		this.year = year;
	}

	public int getNum() {
		return num;
	}

	public void setNum(int num) {
		this.num = num;
	}

	public String getName() {
		return name;
	}

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

	public double getMoney() {
		return money;
	}

	public void setMoney(double money) {
		this.money = money;
	}

	public Phone getPhone() {
		return phone;
	}

	public void setPhone(Phone phone) {
		this.phone = phone;
	}

	public void printinfo() {
		System.out.println("工龄" + year + "年，工号" + num + "，姓名：" + name + "，基本工资" + money + "元,手機：" + phone.getBrand()
				+ "," + phone.getPrice() + "元");
	}
}

public class Phone {
	private String brand;
	private int price;

	public Phone() {
		super();
	}

	public Phone(String brand, int price) {
		super();
		this.brand = brand;
		this.price = price;
	}

	public String getBrand() {
		return brand;
	}

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

	public int getPrice() {
		return price;
	}

	public void setPrice(int price) {
		this.price = price;
	}
}

public class Manager extends Worker {
	private Saler saler;

	public Manager() {
		super();
	}

	public Manager(int year, int num, String name, double money, Phone phone, Saler saler) {
		super(year, num, name, money, phone);
		this.saler = saler;
	}

	public Saler getSaler() {
		return saler;
	}

	public void setSaler(Saler saler) {
		this.saler = saler;
	}

	public double money() {
		System.out.println(getMoney() + 500 + getYear() * 1000);
		return getMoney() + 500 + getYear() * 1000;
	}

	// 打印部门经理谁负责管理的是哪个销售人员，当月的销售金额是XX,表示管理哪个销售人员
	public void manage() {
		System.out.println(
				"部門經理:" + super.getName() + "負責銷售人員:" + saler.getName() + ",當月銷售金額是：" + saler.getSMoney() + "元");
	}
}

public class Saler extends Worker {
	private int SMoney;

	public Saler() {
		super();
	}

	public Saler(int year, int num, String name, double money, Phone phone, int sMoney) {
		super(year, num, name, money, phone);
		SMoney = sMoney;
	}

	public int getSMoney() {
		return SMoney;
	}

	public void setSMoney(int sMoney) {
		SMoney = sMoney;
	}

	// 工资=基本工资+销售金额*系数（其中系数当销售金额大于100W时为0.09，小于100W时为0.08）
	public double money() {
		if (SMoney >= 1000000) {
			System.out.println(getMoney() + SMoney * 0.09);
			return getSMoney() + SMoney * 0.09;
		} else
			System.out.println(getMoney() + SMoney * 0.08);
		return getSMoney() + SMoney * 0.08;
	}
}

public class Test {

	public static void main(String[] args) {
		Phone p1 = new Phone("IPhone", 8000);
		Phone p2 = new Phone("諾基亞", 2000);
		Worker s = new Saler(5, 201, "張三", 5000, p2, 1000000);
		Saler s1 = (Saler) s;
		Worker m = new Manager(10, 101, "李四", 8000, p1, s1);
		Manager m1 = (Manager) m;
		m.printinfo();
		s.printinfo();
		m1.manage();
	}
}