第十二周上机作业
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 chap1; public abstract class Shape { private double area; private double per; private 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 chap1; public class Rectangle extends Shape { private double width; private double height; public Rectangle() {}; public Rectangle(double width, double height, String color) { super(color); this.width = width; this.height = height; } public double getPer() { return (width + height) * 2; } public double getArea() { return width * height; } public void showAll() { System.out.println(String.format("矩形长度%f,宽度%f,面积%f,周长%f,颜色为%s", width, height, getArea(), getPer(), getColor())); } }
package chap1; public class Circle extends Shape { private double radius; public Circle() {}; public Circle(double radius, String color) { super(color); this.radius = radius; } public double getPer() { return 2 * 3.14 * radius; } public double getArea() { return 3.14 * Math.pow(radius, 2); } public void showAll() { System.out.println(String.format("圆半径%f,面积%f,周长%f,颜色为%s", radius, getArea(), getPer(), getColor())); } }
package chap1; public class PolyDemo { public static void main(String[] args) { Rectangle rect = new Rectangle(20, 10, "黄色"); rect.showAll(); Circle ccl = new Circle(20, "白色"); ccl.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 week12; public class ColaEmployee { private String name; private int birthdayMonth; public ColaEmployee(String name, int birthdayMonth) { this.name = name; this.birthdayMonth = birthdayMonth; } public double getSalary(int month) { if (month == birthdayMonth) return 100; return 0; } }
package week12; public class SalariedEmployee extends ColaEmployee { private double monthlyFee; public SalariedEmployee(String name, int birthdayMonth, double monthlyFee) { super(name, birthdayMonth); this.monthlyFee = monthlyFee; } @Override public double getSalary(int month) { return monthlyFee + super.getSalary(month); } }
package week12; public class HourlyEmployee extends ColaEmployee { private double feePerHour; private int hours; public HourlyEmployee(String name, int birthdayMonth, double feePerHour, int hours) { super(name, birthdayMonth); this.feePerHour = feePerHour; this.hours = hours; } @Override public double getSalary(int month) { double fee = 0; if (hours > 160) { fee += feePerHour * 160 + feePerHour * (hours - 160) * 1.5; } else { fee += feePerHour * hours; } fee += super.getSalary(month); return fee; } }
package week12; public class SalesEmployee extends ColaEmployee { private double monthlySale; private double royaltyRate; public SalesEmployee(String name, int birthdayMonth, double monthlySale, double royaltyRate) { super(name, birthdayMonth); this.monthlySale = monthlySale; this.royaltyRate = royaltyRate; } @Override public double getSalary(int month) { double fee = 0; fee += monthlySale * royaltyRate; fee += super.getSalary(month); return fee; } }
package week12; public class Company { public static void printCompany(ColaEmployee emp, int month) { System.out.println(emp.getName() + "的工资额为" + emp.getSalary(month)); } }
package week12; public class TestCompany { public static void main(String[] args) { ColaEmployee[] emps = new ColaEmployee[] { new SalariedEmployee("张三", 4, 18000), new HourlyEmployee("李四", 5, 200, 180), new SalesEmployee("王二麻子", 6, 500000, 0.05) }; for (ColaEmployee emp : emps) { Company.printCompany(emp, 5); } } }
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 week12; public interface Fruit { }
package week12; public class Apple implements Fruit { public Apple() { System.out.println("创建了一个苹果类的对象"); } }
package week12; public class Banana implements Fruit { public Banana() { System.out.println("创建了一个香蕉类的对象"); } }
package week12; public class Grape implements Fruit { public Grape() { System.out.println("创建了一个葡萄类的对象"); } }
package week12; import java.util.Scanner; public class Gardener { public static Fruit create(String type) { switch (type) { case "苹果": return new Apple(); case "香蕉": return new Banana(); case "葡萄": return new Grape(); default: return null; } } public static void main(String[] args) { Scanner s = new Scanner(System.in); Fruit fruit = create(s.next()); if (fruit == null) { System.out.println("不存在的类"); } } }
