java - 为什么找不到我的子类方法(符号)？

Question

我是 Java 的新手，正在编写一个显示继承的简单程序。我在访问派生类中的方法时遇到问题，因为我的变量定义似乎没有使用子类名称，而是使用父类(super class)名称 (Accounts)。为什么调用入金方法会出现找不到符号的错误？

import java.util.*;
import java.text.*;


public class Accounter {

static Scanner input = new Scanner(System.in);
static Accounts myAccount;

public static void main(String[] args) {

    int result; //holder for user input
    double amount; //holder for desposits and withdrawals

    System.out.println("What kind of account would you like to setup?");
    System.out.println("Checking[1] or Savings[2]");
    result = input.nextInt();

    if(result == 1) {
        myAccount = new Checking();
    } else {
        myAccount = new Savings();
    }

    myAccount.deposit(199.99);



}

}

class Accounts {
double balance;
public String accountName;
public Date dateOpened;
public Date today = new Date();

public Accounts() {
    dateOpened = today;
}
public Date getDateOpened() {
    return dateOpened;
}
public double getBalance() {
    return balance;
}
}

class Checking extends Accounts {
public void deposit(double amount) {
    this.balance = this.balance + amount;
}
 }
 class Savings extends Accounts {
public void deposit(double amount) {
    this.balance = this.balance + amount;
}
 }

Answer 1

1. 将 class Accounts 声明为 abstract。

2. 在此类中将double balance声明为protected字段。

3. 在此类中将public void deposit(double amount)声明为抽象方法。