在java中的继承程序中找不到符号错误

Question

import java.io.*;
import java.lang.*;
import java.util.*;
class First 
{
    public int No;
    public String Name; 
    void getDetails() throws IOException
    {
    Scanner sc = new Scanner(System.in);
    No = sc.nextInt();
    Name = sc.nextLine();
    }   
    void showDetails() throws IOException
    {
    System.out.println("The No and Name entered is: " +No  +"\t" +Name);
    }
}

class Second extends First
{
    public double Salary;   
    public void showSalary() throws IOException
    {
    BufferedReader br = new BufferedReader ( new InputStreamReader (System.in) );
    Salary = Double.parseDouble(br.readLine() );
    System.out.println(" The salary for no:" +No +"is" +Salary);
    }
}

class Demo_Inheritance 
{
    public static void main(String s[]) throws IOException
    {
     Second sd = new Second();
     sd.getDetails();
     sd.showDetails();
     sd.showSalary();
    First fs = new First();
    fs.getDetails();
    fs.showDetails();
    fs.showSalary(); }
}

当我执行此编码时，我将最后一行中的错误称为“fs.showSalary（）” - ＆gt;找不到符号“。（点）”

Answer 1

showSalary中未定义方法First。您需要添加方法或使用Second的实例来使用方法

Answer 2

编译器总是根据声明的访问类型来解析方法调用或字段访问。

由于fs的声明类型为First，编译器将在showSalary()类中查找First的方法声明，但找不到。{1}}。因此它给编译器错误。