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 huaerzi; public abstract class homework { protected double area; protected double per; protected String color; public Shape() { } public Shape(String color) { this.color = color; } public abstract void s(); public abstract void c(); public abstract void showAll(); }
package huaerzi; public class homework { double width; double height; public Rectangle() { } public Rectangle(double width, double height, String color) { super(); this.width = width; this.height = height; this.color = color; } @Override public void s() { area = width * height; } @Override public void c() { per = (width + height) * 2; } public void showAll() { System.out.println("矩形面积是:" + area + ",周长是:" + per+",颜色:"+color); } }
package huaerzi; public class Circle extends Shape { double radius; public Circle() { } public Circle(double radius, String color) { this.color = color; this.radius = radius; } @Override public void getArea() { area = radius * radius * 3.14; } @Override public void getPer() { per = 2 * radius * 3.14; } @Override public void showAll() { System.out.println("圆的面积:" + area + ",周长:" + per + ",颜色:" + color); } }
package huaerzi; public class homework { public static void main(String[] args) { Circle circle = new Circle(3, "break"); Rectangle rectangle = new Rectangle(2, 4, "red"); circle.getArea(); circle.getPer(); circle.showAll(); rectangle.getArea(); rectangle.getPer(); rectangle.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。
Ÿ 方法:getSalary(int month) 根据参数月份来确定工资,如果该月员工过生日,则公司会额外奖励100 元。
(2) SalariedEmployee : ColaEmployee 的子类,拿固定工资的员工。
Ÿ 属性:月薪
(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。
Ÿ 属性:每小时的工资、每月工作的小时数
(4) SalesEmployee :ColaEmployee 的子类,销售人员,工资由月销售额和提成率决定。
Ÿ 属性:月销售额、提成率
(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 huaerzi; public class homework{ String name; int month; public ColaEmployee() { } public ColaEmployee(String name, int month) { super(); this.name = name; this.month = month; } public double getSalary(int month) { return 0; } }
package huaerzi; public class SalariedEmployee extends ColaEmployee { double monSalary; public SalariedEmployee() { super(); } public SalariedEmployee(String name, int month, double monSalary) { super(name, month); this.monSalary = monSalary; } public double getSalary(int month) { if (super.month == month) { return monSalary + 100; } else { return monSalary; } } }
package huaerzi; public class HourlyEmployee extends ColaEmployee { private int hourSalary; private int hourNum; public HourlyEmployee(String name, int month, int hourSalary, int hourNum) { super(name, month); this.hourSalary = hourSalary; this.hourNum = hourNum; } public double getSalary(int month) { if (super.month == month) { if (hourNum > 160) { return hourSalary * 160 + hourSalary * (hourNum - 160) * 1.5 + 100; } else { return hourSalary * hourNum + 100; } } else { if (hourNum > 160) { return hourSalary * 160 + hourSalary * (hourNum - 160) * 1.5; } else { return hourSalary * hourNum; } } } }
package huaerzi; 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 huaerzi; 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 huaerzi; public class Text { public static void main(String[] args) { ColaEmployee[] cel = { new SalariedEmployee("salariedEmployee", 6, 25000), new HourlyEmployee("hourlyEmployee", 5, 200, 200), new SalesEmployee("salesEmployee", 3, 60000, 0.3) }; for (int i = 0; i < cel.length; i++) { new Company().getSalary(cel[i], 7); } } }
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”);
}
}
(3)类图如下:
(4)要求从控制台输入一个字符串,根据字符串的值来判断创建三种水果中哪个类的对象。
运行结果如图:
package huaerzi; public class Apple implements Fruit { public Apple() { System.out.println("创建了一个苹果类对象"); } }
package huaerzi; public class Banana implements Fruit { public Banana() { System.out.println("创建了一个香蕉类对象"); } } package huaerzi; public class Grape implements Fruit { public Grape() { System.out.println("创建了一个葡萄类对象"); } } package huaerzi; import java.util.Scanner; public class Gardener { public void creater() { String s = ""; Scanner input = new Scanner(System.in); s = input.nextLine(); if (s.equals("苹果")) { new Apple(); } else if (s.equals("香蕉")) { new Banana(); } else if (s.equals("葡萄")) { new Grape(); } else { System.out.println("请输入正确的对象"); } } } package huaerzi; public class Text { public static void main(String[] args) new Gardener().creater(); } }