云大JAVA实验7Lab #7(陆歌浩)

云南大学软件学院实验报告
课程：Java程序设计实验学期：2012-2013学年第一学期任课教师：陆歌浩
专业：软件工程学号：序号：姓名：成绩：
实验7 继承
一、实验目的
练习Java中继承概念的应用。

二、实验内容
Program 1
Write a program called CollegeCourse that computes the cost of taking a college course. Include a constructor that requires a course ID number.
Add a subclass Lab to compute a lab fee for a course that uses a lab. Write a program UseCourse to use the classes. Save the progras as CollegeCourse, Lab, and UseCourse. Put them all in a package called b7. Hints: how to compile and run your programs in the DOS environment, if using Jcreator you don't have to worry about this
(suppose you put all your work under c:\java\lab7)
Compile the classes by using the command:
javac -d c:\java\lab7\*.java
Run the example by going to c:\java\lab7 and typing:
java ynu/edu/lab7/UseCourse
For example, the output could be:
The cost of your course is $180.0
there is a $25.00 lab fee.
The cost of your course is $205.0
实验代码：
package b7;
public class CollegeCourse
{
protected int id;
public CollegeCourse(int id)
{
this.id = id;
}
public double cost()
{
if(id == 1)
return 180;
else if(id == 2)
return 190;
else
return 200;
}
}
//
package b7;
public class Lab extends CollegeCourse
{
public Lab(int id)
{
super(id);
}
public double cost()
{
if(super.id == 1)
return 25;
else if(super.id == 2)
return 30;
else
return 40;
}
}
//
package b7;
public class UseCourse {
public static void main(String[] args)
{
CollegeCourse course = new CollegeCourse(1);
CollegeCourse lab = new Lab(1);
String str1 = "The cost of your course is $" + course.cost()+"\n";
String str2 = "There is a $" + lab.cost() + " lab fee.\n";
String str3 = "The cost of your course is $" + (course.cost()+lab.cost());
System.out.println(str1+str2+str3+"\n\n孙金文（20101120007）");
}
}
运行截图：
Program 2
Create an abstract Auto class with fields for the car make and price. Include get and set methods for these fields; the setPrice() method is abstract.
Create two suclasses for individual automobile makers (for example, Ford and Chevy) and include appropriate setPrice() methods in each subclass. Finally, write a program that uses the Auto class and subclasses to display information about different cars. The java programs should be named like:
Auto.java
Ford.java
Chevy.java
UseAuto.java
Sample Output:
A new Ford costs $20000.0
A new Chevy costs $22000.0
实验代码：
package b7;
import javax.swing.JOptionPane;
abstract class Auto{
protected double price;
private String maker;
public abstract void setPrice(double price);
public double getPrice(){
return price;
}
public void setMaker(String maker){
this.maker = maker;
}
public String getMaker(){
return maker;
}
}
class Ford extends Auto{
public void setPrice(double price){
this.price=price;
}
public Ford(){}
}
class Chevy extends Auto{
public void setPrice(double price){
this.price=price;
}
public Chevy(){}
}
public class UseAuto{
public static void main(String[] args){
Auto ford = new Ford();
Auto chevy = new Chevy();
ford.setMaker("Ford");
ford.setPrice(20000);
chevy.setMaker("Chevy");
chevy.setPrice(22000);
JOptionPane.showMessageDialog(null,
"A new "+ford.getMaker()
+" costs $"+ford.getPrice()
+"\nA new "+chevy.getMaker()
+" costs $"+chevy.getPrice(),
"孙金文（20101120007）", JOptionPane.PLAIN_MESSAGE);
}
}
运行截图：。