我是Java新手。最近我一直在研究构造函数、继承、数组和抽象类。我正在尝试将所有这些概念结合到代码中以供实践。
我有一个抽象基类Person3，一个子类Student1和一个子类Staff1。我还有一个驱动程序。
在编译时，我收到了关于Student1和Staff1构造函数的错误，并希望得到一些澄清，因为我只是没有看到这些问题。
有人能详细解释一下为什么会出现这些错误吗?谢谢!
错误:
no suitable constructor found for Student1(String,Date,int,double,double)
Student1 st = new Student1("Jack", new Date("May", 8, 1990), 00000001, 7.50, 7.00);
^
constructor Student1.Student1(Student1) is not applicable
(actual and formal argument lists differ in length)
constructor Student1.Student1(String[],Date[],int[],double[],double[]) is not applicable
(actual argument String cannot be converted to String[] by method invocation conversion)
constructor Student1.Student1() is not applicable
(actual and formal argument lists differ in length)
no suitable constructor found for Staff1(String,Date,int,double,double,double)
myPerson[1] = new Staff1("Will", new Date("July", 10, 1998), 00000002, 7.00, 8.00, 3900.00);
^
constructor Staff1.Staff1(Staff1) is not applicable
(actual and formal argument lists differ in length)
constructor Staff1.Staff1(String[],Date[],int[],double[],double[],double[]) is not applicable
(actual argument String cannot be converted to String[] by method invocation conversion)
constructor Staff1.Staff1() is not applicable
(actual and formal argument lists differ in length)
适用于Student1类的代码:
public class Student1 extends Person3
{
private double [] wageRate;
private double [] hours;
public Student1(){
super( );
for(int i = 0; i < wageRate.length; i++) {
wageRate[i] = 0.00;
}
for(int i = 0; i < hours.length; i++){
hours[i] = 0.00;
}
}
public Student1(String [] theName, Date [] theDate, int [] theSocial, double [] theWageRate, double [] theHours){
super(theName, theDate, theSocial);
if ((theWageRate != null) && (theHours != null)){
wageRate = theWageRate;
hours = theHours;
}
else{
System.out.println("Fatal Error: creating an illegal hourly employee.");
System.exit(0);
}
}
public Student1(Student1 originalObject)
{
super(originalObject);
wageRate = originalObject.wageRate;
hours = originalObject.hours;
}
Staff1类适用代码:
public class Staff1 extends Person3
{
private double [] salary;
public Staff1()
{
super( );
for(int i = 0; i < salary.length; i++){
salary[i]=0.00;
}
}
public Staff1(String [] theName, Date [] theDate, int [] theSocial, double [] theWageRate, double [] theHours, double [] theSalary){
super(theName, theDate, theSocial);
if (theSalary != null)
salary = theSalary;
else
{
System.out.println("Fatal Error: Negative salary.");
System.exit(0);
}
}
public Staff1(Staff1 originalObject){
super((Person3)originalObject);
salary = originalObject.salary;
}
驱动程序尝试以下操作并收到错误:
Student1 st= new Student1("Jack", new Date("May", 8, 1990), 00000001, 7.50, 7.00);
myPerson[1] = new Staff1("Will", new Date("July", 10, 1998), 00000002, 7.00, 8.00, 3900.00);
您是否意识到Type[]意味着" Type的数组"?
根据这两个构造函数声明:
public Student1(String [] theName, Date [] theDate, int [] theSocial, double [] theWageRate, double [] theHours)
public Staff1(String [] theName, Date [] theDate, int [] theSocial, double [] theWageRate, double [] theHours, double [] theSalary)
所有参数必须为数组。
但是从错误消息中可以清楚地看出，您正在向构造函数传递普通值。
从构造函数声明中删除所有的[]，你应该没事。
或者，如果实参实际上都是数组，则必须这样调用构造函数:
Student1 st = new Student1(new String[]{"Jack"}, new Date[]{new Date("May", 8, 1990)}, new int[]{1}, new double[]{7.50}, new double[]{7.00});
myPerson[1] = new Staff1(new String[]{"Will"}, new Date[]{new Date("July", 10, 1998)}, new int[]{2}, new double[]{7.00}, new double[]{8.00}, new double[]{3900.00});
学生的构造函数:
public Student1(String [] theName, Date [] theDate, int [] theSocial, double [] theWageRate, double [] theHours)
接受数组作为参数。但是，当您初始化学生对象时:
new Student1("Jack", new Date("May", 8, 1990), 00000001, 7.50, 7.00);
你没有使用数组，只是简单的值。您要么需要修改构造函数以接受单个值，要么需要使用对象数组创建student。
构造函数接受数组作为参数。您需要将其更改为:
public Student1(String theName, Date theDate, int theSocial, double theWageRate, double theHours)
要了解有关数组的更多信息，请查看https://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html