对于家庭作业,我正在使用以下三个班级。
Class | Extends | Variables
--------------------------------------------------------
Person | None | firstName, lastName, streetAddress, zipCode, phone
CollegeEmployee | Person | ssn, salary,deptName
Faculty | CollegeEmployee | tenure(boolean)
我无法让Faculty构造函数正确使用超类中的数据。
import java.util.*;
import javax.swing.*;
public class Faculty extends CollegeEmployee
{
protected String booleanFlag;
protected boolean tenured;
public Faculty(String firstName, String lastName, String streetAddress,
String zipCode, String phoneNumber, String ssn,
String department, double salary)
{
super(firstName,lastName,streetAddress,zipCode,phoneNumber,
department,ssn,salary);
String booleanFlag = JOptionPane.showInputDialog(null, "Tenured (Y/N)?");
if(booleanFlag.equals("Y"))
tenured = true;
else
tenured = false;
}
public void setTenure(boolean tenured)
{ this.tenured = tenured; }
public boolean getTenured()
{ return tenured; }
public void display()
{
super.display();
JOptionPane.showMessageDialog(null, "Tenured: " + tenured);
}
}
CollegeEmployee
下降的Faculty
类出现在下面。
import java.util.*;
import javax.swing.*;
public class CollegeEmployee extends Person
{
protected String ssn;
protected String sal;
protected double annSalary;
protected String department;
public CollegeEmployee(String firstName, String lastName,
String streetAddress, String zipCode,
String phoneNumber)
{
super(firstName,lastName,streetAddress,zipCode,phoneNumber);
ssn = JOptionPane.showInputDialog(null, "Enter SSN ");
department = JOptionPane.showInputDialog(null, "Enter department: ");
sal = JOptionPane.showInputDialog(null, "Enter salary: ");
annSalary = Double.parseDouble(sal);
}
public void setFirstName(String firstName)
{ this.firstName = firstName; }
public String getFirstName()
{ return firstName; }
... ETC ... REMAINING GET/SET METHODS ELIMINATED FOR BREVITY.
我得到的错误指向参数之间的不匹配... Faculty
调用八个参数,但CollegeEmployee
只有五个。但是,我认为通过扩展CollegeEmployee
扩展Person
,我可以在调用此类时访问所有八个字段。正如已经指出的那样,情况并非如此。我只有Person
的五个字段。所以我明显的下一个问题是我如何从ssn, department and salary
到CollegeEmployee
获得Faculty
?那是我失踪的那件作品。我一直在研究Java教程并试验了几个小时,但仍然无法得到我需要做的修正。我是否需要通过People
调用CollegeEmployee
变量,然后在CollegeEmployee
中实例化Faculty
个变量?我对做什么感到非常困惑,迫切需要一些指导......
感谢加载,在我仔细阅读教程中的super()关键字部分后,我会回过头来看看。
答案 0 :(得分:3)
构造函数中的super()
调用调用父类构造函数。在这种情况下,父类CollegeEmployee
的构造函数接受五个参数但是传递八个不正确。
请参阅Keyword super Tutorial,特别是子类构造函数部分。
答案 1 :(得分:2)
在Faculty.java中你有: 超级(名字,姓氏,的StreetAddress,邮政编码,phoneNumber的,部门,SSN,薪水);
这是物理上调用CollegeEmployee的构造函数,它只有五个参数。这是编译错误。
类可能包含未在构造函数中设置的变量。您可以拥有空构造函数并在另一个方法中设置变量。
由于存在继承结构,因此您只能通过super()设置父变量。