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 study; public abstract class Shape { double area; double per;//perimeter String color; public Shape() { } public Shape(String color) { super(); this.color = color; } public abstract void getArea(); public abstract void getPer(); public abstract void showAll(); public String getColor() { return color; } public void setColor(String color) { this.color = color; } } package study; public class Rectangle extends Shape{ double length; double width; public Rectangle() { } public Rectangle(double a, double b,String c) { super(); length=a; width=b; color=c; } @Override public void getArea() { // TODO Auto-generated method stub area=length*width; } @Override public void getPer() { // TODO Auto-generated method stub per=(length+width)*2; } @Override public void showAll() { // TODO Auto-generated method stub System.out.println("颜色是"+color+"面积是"+area+"周长是"+per); } } package study; public class Circle extends Shape{ double radius; public Circle() { } public Circle(double radius,String a) { super(); this.radius = radius; color=a; } @Override public void getArea() { // TODO Auto-generated method stub area=radius*radius*3.14; } @Override public void getPer() { // TODO Auto-generated method stub per=2*radius*3.14; } @Override public void showAll() { // TODO Auto-generated method stub System.out.println("颜色是"+color+"半径是"+radius+"面积是"+area+"周长是"+per); } } package study; public class PolyDemo { public static void main(String[] args) { // TODO Auto-generated method stub Rectangle r=new Rectangle(3,4,"月白"); r.getArea(); r.getPer(); r.showAll(); Circle c=new Circle(2.0,"橙黄"); c.getArea(); c.getPer(); 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 Cola; public abstract class ColaEmployee { String name; int birthmonth; public ColaEmployee() { } public ColaEmployee(String name, int birthmonth) { this.name = name; this.birthmonth = birthmonth; } abstract double getSalary(int month) ; } package Cola; public class SalariedEmployee extends ColaEmployee{ double salar; public SalariedEmployee() { } public SalariedEmployee(String name, int birthmonth,double salar) { super(name,birthmonth); this.salar=salar; } @Override double getSalary(int month) { if(month==birthmonth) { salar+=100; } return salar; } } package Cola; public class HourlyEmployee extends ColaEmployee{ double shourly; double hours; public HourlyEmployee() { super(); // TODO Auto-generated constructor stub } public HourlyEmployee(String name, int birthmonth,double shourly,double hours) { super(name, birthmonth); // TODO Auto-generated constructor stub this.shourly=hours; this.hours=hours; } double getSalary(int month) { if(hours>160.0) { shourly=(160.0*shourly)+(hours-160.0)*(shourly*1.5); }else { shourly=hours*shourly; } if(month==birthmonth) { shourly+=100.0; return shourly; }else { return shourly; } } } package Cola; public class SalesEmployee extends ColaEmployee{ double smonthly; double rate; public SalesEmployee() { super(); // TODO Auto-generated constructor stub } public SalesEmployee(String name, int birthmonth, double smonthly,double rate) { super(name, birthmonth); // TODO Auto-generated constructor stub this.smonthly=smonthly; this.rate=rate; } public double getSalary(int month) { smonthly=smonthly+smonthly*rate; if(month==birthmonth) { smonthly+=100; return smonthly; }else { return smonthly; } } } package Cola; public class Company{ public static void getSalary(ColaEmployee a,int month) { System.out.println(month+"月"+a.name+"员工"+"的月薪是"+a.getSalary(month)+"元。"); } } package Cola; public class TestCompany { public static void main(String[] args) { // TODO Auto-generated method stub ColaEmployee [] b=new ColaEmployee[6]; b[0]=new SalesEmployee("王伟", 4, 10000, 5); b[1]=new SalesEmployee("刘美",8,12000,5); b[2]=new SalariedEmployee("张钧", 11, 20000); b[3]=new SalariedEmployee("高晟", 2, 23000); b[4]=new HourlyEmployee("季澊", 9, 200, 168); b[5]=new HourlyEmployee("沈复",5,300,170); for (ColaEmployee a:b) { Company.getSalary(a,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 study; public interface Fruit { } package study; public class apple implements Fruit { public apple() { super(); // TODO Auto-generated constructor stub System.out.println("创建了一个苹果类的对象"); } } package study; public class Banana implements Fruit { public Banana() { super(); // TODO Auto-generated constructor stub System.out.println("创建了一个香蕉类的对象"); } } package study; public class Pear implements Fruit { public Pear() { super(); // TODO Auto-generated constructor stub System.out.println("创建了一个梨类的对象"); } } package study; import java.util.Scanner; public class Garder { public void creater() { System.out.println("请输入你想创建的果园(苹果,梨,香蕉):"); 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("梨")) { new Pear(); } else { System.out.println("请输入正确的对象"); } } } package study; public class Test { public static void main(String[] args) { // TODO Auto-generated method stub new Garder().creater(); } }