java - 在java中使用继承和对话框

Question

我在 java 中创建了三个类:

大学类(class)

package CollegeCourse;
import javax.swing.JOptionPane;
public class CollegeCourse {

protected String Dept;
protected int CourseNum;
protected int Cred;
protected int fee;
protected int Charge = 120;
protected int labfee;

public void inputDepartment(){
    Dept = JOptionPane.showInputDialog(null, "Enter Department");
}

public void inputCourseNumber(){
    String CourseNumString = new String(" ");
    CourseNumString = JOptionPane.showInputDialog(null, "Enter Course Number");
    CourseNum = Integer.parseInt(CourseNumString);
}

public void inputCredits(){
    String CredString = new String(" ");
    CredString = JOptionPane.showInputDialog(null, "Enter Credits");
    Cred = Integer.parseInt(CredString);
}

 public void displayNonLabCourse(){
    fee = Cred * Charge;
    JOptionPane.showMessageDialog(null, Dept + CourseNum + 
            "\nNon-lab Course" + "\n" + Cred +" Credits" + "\nTotal fee is $" + fee);
 }

实验室类(class)

package CollegeCourse;
import javax.swing.JOptionPane;
public class LabCourse extends CollegeCourse {

 public void displayLabCourse(){
    labfee = fee + 50;
    JOptionPane.showMessageDialog(null, Dept + CourseNum + 
            "\nLab Course" + "\n" + Cred +" Credits" + "\nTotal fee is $" + fee);
 }
 }

使用类(class)

package CollegeCourse;
public class UseCourse{
public static void main(String[] args) {
    CollegeCourse college = new CollegeCourse();
    college.inputDepartment();
    college.inputCourseNumber();
    college.inputCredits();
    college.displayNonLabCourse();
    }
}

如何让UseCourse类在用户输入“BIO”之类的某个部门时显示LabCourse的显示方法？？？

创建一个名为 CollegeCourse 的类，其中包含保存部门的数据字段(例如 ENG)、类(class)编号(例如 101)、学分(例如 3)、类(class)费用(例如 360 美元)。所有字段都需要作为参数给 build 者，费用除外，费用按每学分时 120 美元计算。包括显示类(class)数据的 display() 方法。创建一个名为 LabCourse 的子类类(class)费用增加 50 美元。覆盖父类的 display() 方法以表明course 是显示所有数据的实验类(class)。编写一个名为 UseCourse 的应用程序提示用户输入信息。如果用户进入以下任何部门的类(class)，创建一个 LabCourse:BIO、CHM、CIS 或 PHY。如果用户进入任何其他部门，创建不包括实验室费用的大学类(class)。然后显示类(class)数据。保存文件如 CollegeCourse.java、LabCourse.java 和 UseCourse.java。

Answer 1

这与您最初的实现方式大不相同。但我相信它会做你想做的事。可能有更好的实现方式，但我只是根据您提供的信息实现。希望你明白这一切...

使用类(class):

import javax.swing.JOptionPane;

public class UseCourse
{   
    public UseCourse()
    {
        CollegeCourse college;
        // Collect all the necessary data first to determine whether it is a lab course or not.
        String dept = JOptionPane.showInputDialog(null, "Enter Department");

        String courseNumString = JOptionPane.showInputDialog(null, "Enter Course Number");
        int courseNum = Integer.parseInt(courseNumString);

        String credString = JOptionPane.showInputDialog(null, "Enter Credits");
        int cred = Integer.parseInt(credString);

        // Now that we have the info we can ask the question.
        if (dept.equals("BIO") | dept.equals("CHM") | dept.equals("CIS") | dept.equals("PHY"))
        {college = new LabCourse(dept, courseNum, cred);}

        else {college = new LabCourse(dept, courseNum, cred);}
        college.display();
    }

    public static void main(String[] args) 
    {new UseCourse();}
}

大学类(class):

import javax.swing.JOptionPane;
public class CollegeCourse {

protected String dept;
protected int courseNum;
protected int cred;
protected int fee;
protected int Charge = 120;
protected int labfee;

public CollegeCourse(String dept, int courseNum, int cred)
{
    this.dept = dept;
    this.courseNum = courseNum;
    this.cred = cred;
    fee = cred * Charge;
}

public void display(){

    JOptionPane.showMessageDialog(null, dept + courseNum + 
            "\nNon-lab Course" + "\n" + cred +" Credits" + "\nTotal fee is $" + fee);
 }
}

实验室类(class):

import javax.swing.JOptionPane;
public class LabCourse extends CollegeCourse 
{
    public LabCourse(String dept, int courseNum, int cred)
    {super(dept, courseNum, cred);}

    public void display()
    {
        fee += 50;
        JOptionPane.showMessageDialog(null, dept + courseNum + 
                "\nLab Course" + "\n" + cred +" Credits" + "\nTotal fee is $" + fee);
    }  
}