1、设计四个类,分别是:(知识点:抽象类及抽象方法)
(1)Shape表示图形类,有面积属性area、周长属性per,颜色属性color,有两个构造方法(一个是默认的、一个是为颜色赋值的),还有3个抽象方法,分别是:getArea计算面积、getPer计算周长、showAll输出所有信息,还有一个求颜色的方法getColor。
(2)2个子类:
1)Rectangle表示矩形类,增加两个属性,Width表示长度、height表示宽度,重写getPer、getArea和showAll三个方法,另外又增加一个构造方法(一个是默认的、一个是为高度、宽度、颜色赋值的)。
2)Circle表示圆类,增加1个属性,radius表示半径,重写getPer、getArea和showAll三个方法,另外又增加两个构造方法(为半径、颜色赋值的)。
(3)一个测试类PolyDemo,在main方法中,声明创建每个子类的对象,并调用2个子类的showAll方法。
package chap3; public abstract class Shape { protected double area; protected double per; protected String color; public Shape() { } public Shape(String color) { this.color = color; } public abstract double getArea(); public abstract double getPer(); public abstract void showAll(); public String getcolor() { return this.color; } }
package chap3; public class Rectangle extends Shape { int weigth; int height; public Rectangle() { } public Rectangle(int weigth, int height, String color) { super(); this.weigth = weigth; this.height = height; this.color = color; } public double getArea() { this.area = weigth * height; return this.area; } public double getPer() { this.per = 2 * (weigth + height); return this.per; } public void showAll() { System.out.println("该矩形长为" + this.weigth + ",宽为" + this.height + ",周长为" + this.getPer() + ",面积为" + this.getArea() + ",颜色为" + this.getcolor()); } }
package chap3; public class Circle extends Shape { double radius; double pi = Math.PI; public Circle() { } public Circle(double radius, String color) { this.radius = radius; this.color = color; } public double getArea() { double area = pi * radius * radius; return area; } public double getPer() { double per = 2 * pi * radius; return per; } public void showAll() { System.out.println( "半径为" + this.radius + "的圆,周长为" + this.getPer() + ",面积为" + this.getArea() + ",颜色为" + this.getcolor()); } }
package chap3; public class PolyDemo { public static void main(String[] args) { Rectangle a = new Rectangle(2, 5, "yellow"); Circle b = new Circle(2, "black"); a.showAll(); b.showAll(); } }
2、Cola公司的雇员分为以下若干类:(知识点:多态)
(1) ColaEmployee :这是所有员工总的父类,属性:员工的姓名,员工的生日月份。
(2) SalariedEmployee : ColaEmployee 的子类,拿固定工资的员工。
(3) HourlyEmployee :ColaEmployee 的子类,按小时拿工资的员工,每月工作超出160 小时的部分按照1.5 倍工资发放。
(4) SalesEmployee :ColaEmployee 的子类,销售人员,工资由月销售额和提成率决定。
(5) 定义一个类Company,在该类中写一个方法,调用该方法可以打印出某月某个员工的工资数额,写一个测试类TestCompany,在main方法,把若干各种类型的员工放在一个ColaEmployee 数组里,并单元出数组中每个员工当月的工资。
package chap3; public class ColaEmployee { String name; int month; public ColaEmployee() { super(); // TODO Auto-generated constructor stub } public ColaEmployee(String name, int month) { super(); this.name = name; this.month = month; } public double getSalary(int month) { return 0; } }
package chap3; public class SalesEmployee extends ColaEmployee{ private int monthSales; private double royaltyRate; public SalesEmployee(String name, int month, int monthSales, double royaltyRate) { super(name, month); this.monthSales = monthSales; this.royaltyRate = royaltyRate; } public double getSalary(int month) { if (super.month == month) { return monthSales * royaltyRate + 100; } else { return monthSales * royaltyRate; } } }
package chap3; public class Company { public void getSalary(ColaEmployee c, int month) { System.out.println(c.name + "在" + month + "月的月薪为" + c.getSalary(month) + "元"); } }
package chap3; public class TestCompany { public static void main(String[] args) { // TODO Auto-generated method stub ColaEmployee[] cel= {new SalariedEmployee("jack", 6, 10000),new HourlyEmployee("按小时拿工资的员工", 10, 50, 200),new SalesEmployee("销售人员", 6, 20000, 0.8)}; for (int i = 0; i < cel.length; i++) { new Company().getSalary(cel[i], 8); } } }
package chap3; public class HourlyEmployee extends ColaEmployee{ private int hourSalary; private int num; public HourlyEmployee(String name,int month,int hourSalary, int num) { super(name,month); this.hourSalary = hourSalary; this.num = num; } public double getSalary(int month) { if (super.month == month) { if (num>160) { return hourSalary * 160 + hourSalary * (num - 160) * 1.5 +100; } else { return hourSalary * num + 100; } } else { if (num >160) { return hourSalary * 160 + hourSalary * (num - 160) * 1.5; } else { return hourSalary * num; } } } }
3、利用接口实现动态的创建对象:(知识点:接口 )
(1)创建4个类
1苹果
2香蕉
3葡萄
4园丁
(2)在三种水果的构造方法中打印一句话.
以苹果类为例
class apple
{
public apple()
{
System.out.println(“创建了一个苹果类的对象”);
}
package chap3; public class apple implements Fruit { public apple() { System.out.println("创建了一个苹果类对象"); } }
package chap3; public interface Fruit { }
package chap3; public class banana implements Fruit { public banana() { System.out.println("创建了一个香蕉类对象"); } }
package chap3; public class grape implements Fruit { public grape() { System.out.println("创建了一个葡萄类对象"); } }
package chap3; import java.util.Scanner; public class gardener { public void creater() { Scanner input = new Scanner(System.in); String a = input.next(); if (a.equals("苹果")) { new apple(); } else if (a.equals("香蕉")) { new banana(); } else if (a.equals("葡萄")) { new grape(); } else { System.out.println("请重新运行"); } } public static void main(String[] args) { new gardener().creater(); } }