java面向对象编程.doc

信 息 工 程 学 院实验报告的内容与格式按任课教师的要求书写。 Java程序设计 实验/实习报告学院:理学院班级:计算101姓名:洪龙龙学号:2010014549 成绩:A面向对象编程1、 实验/实习过程实验题1：解释下列源程序文件class CCircle /定义一个类double pi; /声明一个double类型的变量表示圆周率 double radius; /声明一个double类型成员表示的半径 double getRadius() /声明了一个友好方法,获取的半径并返回 return radius; void setCircle(double r, double p)/设置圆周率pi和的半径的值 pi=p; /this.pi=p radius=r; /this.radius=r public class Ex2_1 /主类public static void main(String args) /程序的执行入口 CCircle cir1=new CCircle(); /创建了一个类实例 cir1.setCircle(2.0,3.1416); /设置的半径和圆周率分别为2.0和3.1416 System.out.println(radius=+cir1.getRadius(); /打印出的半径值 程序的运行结果:实习题2：设计一个汽车类：源代码：/* Ex2_1.java */class Car String ownerName;/车主姓名 double curSpeed; /当前车速 double curAngle; /车方向盘的当前角度 public void setSpeed(double speed) /设置汽车的速度 curSpeed=speed; public void brake()/停车 curSpeed=0.00; public class Ex2_1public static void main(String args)Car car=new Car();car.setSpeed(60.0);System.out.println(当前车速为:+car.curSpeed);car.brake();System.out.println(刹车后车速为:+car.curSpeed);实习题3:源代码: /* Test.java */class MyProgram private int data;/类中的私有int数据成员 private String str;/类中的私有String数据成员 public void setData(int d)/公有方法,用于设置成员变量data的值 data=d; public void setStr(String s)/公有方法,用于设置str的值 str=s; public int getData()/获取成员data的值 return data; public String getStr()/获取成员str的值 return str; public String toStr()/将str和data分别以字符串的形式打印出来 Integer newData=new Integer(data); return 字符串本身:+str.toString()+t数字转换为字符串后的结果:+newData.toString(); public class Test public static void main(String args) MyProgram program=new MyProgram(); program.setData(315); program.setStr(消费者权益保护日); System.out.println(整数成员:+program.getData(); System.out.println(字符串成员:+program.getStr(); System.out.println(program.toStr(); 程序的运行结果:实习题4：源代码： /* MyCount.java */class Accountprivate double leftMoney;/私有数据成员,类对象必须通过调用get方法获得数据private int number;public Account(double money,int num) /定义了一个带参构造器来初始化类leftMoney=money;number=num;public void saveMoney(double s) /存款,将存入的累积到leftMoney中leftMoney+=s;public double getLeftMoney() /获得当前存款return leftMoney;public void getMoney(double money) /取款if(money=leftMoney)/如果取款小于等于存款,则从存款减去取款,剩余的 leftMoney-=money; /重新计入存款else /反之则不能取款System.out.println(只能取:+leftMoney);public class MyCount public static void main(String args)Account ba=new Account(888123,1000);ba.saveMoney(21000);System.out.println(存入21000元后余额为:+ba.getLeftMoney();ba.getMoney(11500);System.out.println(取出11500元后余额为:+ba.getLeftMoney();程序运行结果：实习题5:源代码: /* Shapes.java */class Shapevoid draw() /基类Shape的draw方法void erase() /基类Shape的erase方法class Circle extends Shape /Circle类直接继承父类Shapevoid draw() /子类Circle对父类Shape的draw方法进行覆盖System.out.println(Circle.draw();void erase()/子类Circle对父类Shape的erase方法进行覆盖System.out.println(Circle.erase();class Square extends Shape/Square类直接继承父类Shapevoid draw()/子类Suqare对父类Shape的draw方法进行覆盖System.out.println(Square.draw();void erase()/子类Square对父类Shape的erase方法进行覆盖System.out.println(Square.erase();class Triangle extends Shape/Triangle类直接继承父类Shapevoid draw()/子类Triangle对父类Shape的draw方法进行覆盖System.out.println(Triangle.draw();void erase()/子类Triangle对父类Shape的erase方法进行覆盖System.out.println(Triangle.erase();public class Shapes public static Shape randShape() /randShape方法返回Shape类的子类对象 switch(int)(Math.random()*3) default: case 0: return new Circle(); case 1: return new Square(); case 2: return new Triangle(); public static void main(String args) Shape s=new Shape9; for(int i=0;is.length;i+) si=randShape(); for(int i=0;is.length;i+) si.draw(); 程序的运行结果:程序解释:该java程序中几个类的泛化关系(不知道在UML类图里面友好方法是否用”+”修饰)如下:Shape类是子类Circle、Square、Triangle类的直接父类.由于在for循环中,si是Shape类型的,但si是各个子类的上转型对象,在main方法中被调用时,由于子类覆盖了父类的draw和erase方法,父类的方法被隐藏,因此调用子类的draw、erase方法,体现了java的运行多态性.运行结果如上截图.实习题6：修改之后的源代码文件:/* Mobile.java */public class Mobile /*Holds the name of mobile*/private String name;/*Holds the price of mobile*/private float price;/*Creates a new mobile object*/*Gets the total number of mobiles*/private static int count=0; /该私有静态成员变量用于记录手机对象的个数public Mobile(String name,float price)=name;this.price=price;count+; /每创建一个对象,个数累积增1./*Gets the name of mobile*/public String getName()return name;/*Gets the price of mobile*/public float getPrice()return price;/*Gets the total number of Mobile objects*/public static int getCount()return count;/* MobileManagement.java */import javax.swing.JOptionPane;public class MobileManagement /*Defines the entry point of the application*/public static void main(String args)/ Create two mobile phone objectsMobile mobile1=new Mobile(E365,1780);Mobile mobile2=new Mobile(M330,1450);/Display the two mobile phones in a dialog box.JOptionPane.showMessageDialog(null,Mobile phones：nn+mobile1.getName()+ +mobile1.getPrice()+ RMB+n+mobile2.getName()+ +mobile2.getPrice()+ RMB+nn+There are +Mobile.getCount()+ mobile phones.);程序的运行结果:实习题7：源程序 /*Product.java*/package .nwsuaf.jp.p4.data;public abstract class Product implements Comparable /*Holds the name of the product.*/ protected String name; /*Holds the price of the product.*/ protected float price; /*Holds the number of the products.*/ protected static int count; /*Create a new product object.*/ protected Product(String name,float price) =name; this.price=price; +count; /*Gets the name of the product.*/ public String getName() return name; /*Gets the price of the product.*/ public float getPrice() return price; /*Gets the total number of products.*/ public static int getCount() return count; /*Compares the product with the given product.*/ public int compareTo(Product product) return new Float(product.getPrice().compareTo(price); /*Mobile.java*/package .nwsuaf.jp.p4.data;class Mobile extends Product protected String manufacture; protected Mobile(String m,String n,float p) super(n,p); manufacture=m; public String getManufacture() return manufacture; public String toString() return name+ on+getManufacture()+,+getPrice()+ RMB; /*Mp3Player.java*/package .nwsuaf.jp.p4.data;class Mp3Player extends Product protected int memorySize; protected Mp3Player(String n,int m,float p) super(n,p); memorySize=m; public int getMemorySize() return memorySize; public String toString() return name+(+memorySize+ MB)+,+getPrice()+ RMB; /*Store.java*/package .nwsuaf.jp.p4;import java.util.Arrays;import javax.swing.JOptionPane;import .nwsuaf.jp.p4.data.Mobile;import .nwsuaf.jp.p4.data.Mp3Player;import .nwsuaf.jp.p4.data.Product;public class Store /*Defines the entry point of the application .*/ public static void main(String args) /creates two mobile phone objects Mobile mobile1=new Mobile(China Mobile,E365,1780); Mobile mobile2=new Mobile(China Mobile,M330,1450); Mp3Player player1=new Mp3Player(Meizo X3,256,399);