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 sg; public abstract class Shape { double area; double per; String color; public Shape() { } public Shape(double area,double per,String color) { this.area=area; this.per=per; this.color=color; } public Shape(String color) { this.color=color; } public String getColor() { return color; } public abstract double getArea() ; public abstract double getPer(); public abstract void showAll(); }
package sg; public class Rectangle extends Shape { double width; double height; public Rectangle(double width,String color, double height) { super(color); this.width=width; this.height=height; } @Override public double getArea() { return area=width*height; } @Override public double getPer() { return per=width*2+height*2; } @Override public void showAll() { System.out.println("图形的面积为"+getArea()+",周长为"+getPer()+",颜色为"+getColor()); } }
package sg; public class Circle extends Shape{ double radius; public Circle(double radius,String color) { super(color); this.radius=radius; } @Override public double getArea() { return area=4*3.14*radius*radius; } @Override public double getPer() { return per=2*3.14*radius; } @Override public void showAll() { System.out.println("图形的面积为"+getArea()+",周长为"+getPer()+",颜色为"+getColor()); } }
package sg; public class PolyDemo { public static void main(String[] args) { Rectangle r=new Rectangle(3, "红色", 4); Circle c=new Circle(2.1, "蓝色"); r.showAll(); c.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。
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。
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。
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。
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 sg; public class ColaEmployee { String name; int month; public ColaEmployee() { super(); } public ColaEmployee(String name, int month) { super(); this.name = name; this.month = month; } public double getSalary(int month){ return month; } }
package sg; public class SalariedEmployee extends ColaEmployee{ double monthsalary ; public SalariedEmployee() { super(); } public SalariedEmployee(String name, int mouth ,double monthsalary) { super(name, mouth); this.monthsalary = monthsalary; } @Override public double getSalary(int month) { if (super.month == month) { return monthsalary + 100; } else { return monthsalary; } } }
package sg; public class HourlyEmployee extends ColaEmployee{ int hourSalary; int hour; public HourlyEmployee() { super(); } public HourlyEmployee(String name, int month, int hourSalary, int hour) { super(name, month); this.hourSalary = hourSalary; this.hour = hour; } @Override public double getSalary(int month) { if(super.month == month){ if (hour > 160) { return hourSalary * 160+ (hour-160)*1.5*hourSalary + 100; }else { return hourSalary * hour + 100; } }else{ if (hour > 160) { return hourSalary * 160 +(hour - 160)*1.5*hourSalary ; }else { return hourSalary * hour; } } } }
package sg; public class SalesEmployee extends ColaEmployee{ double monthsalary; double monthcommission ; public SalesEmployee(String string, int i, int j, double d) { super(); } public SalesEmployee(String name,int month,double monthsalary, double monthcommission) { super(name,month); this.monthsalary = monthsalary; this.monthcommission = monthcommission; } @Override public double getSalary(int month) { if (super.month == month) { return monthsalary*monthcommission + 100; } else { return monthsalary*monthcommission; } } }
package sg; public class Company { public void getSalary(ColaEmployee c, int month) { System.out.println(c.name + "在" + month + "月的月薪是:" + c.getSalary(month) + "元"); } }
package sg; public class TestCompany { public static void main(String[] args) { ColaEmployee[] cel = { new SalariedEmployee("拿固定工资的员工", 1, 8500), new HourlyEmployee("按小时拿工资的员工", 2, 100,85), new SalesEmployee("销售人员", 3, 70000, 0.1) }; for (int i = 0; i < cel.length; i++) { new Company().getSalary(cel[i],3); } } }
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 sg; import java.util.Scanner; public interface Fruit { } class Apple implements Fruit{ public Apple() { System.out.println("创建了一个苹果对象"); } } class Banana implements Fruit{ public Banana() { System.out.println("创建了一个香蕉对象"); } } class Grape implements Fruit{ public Grape() { System.out.println("创建了一个葡萄对象"); } } class Gardener{ public Fruit create() { Scanner input = new Scanner(System.in); String name = input.next(); Fruit fruit = null; switch(name){ case "苹果": fruit = new Apple(); break; case "香蕉": fruit = new Banana(); break; case "葡萄": fruit = new Grape(); break; } input.close(); return fruit; } }
package sg; public class Test1 { public static void main(String[] args) { Gardener g = new Gardener(); g.create(); } }