Java新手求助：如何让主类调用子类BankAccount的menu方法正常运行？

你的代码核心问题是BankAccount类的menu()方法未完成：只写了开头的部分菜单输出，缺少完整的选项列表、用户输入处理逻辑、功能调用代码，甚至连方法和类的闭合大括号都没有，导致程序执行到一半就结束，无法显示完整菜单或执行后续功能。

修正后的完整代码 #

import java.util.Scanner;

public class BankApplication {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter your 'Name' and 'CustomerId' to access your Bank account:");
        String name = sc.nextLine();
        String customerId = sc.nextLine();
        BankAccount obj1 = new BankAccount(name, customerId);
        obj1.menu();
    }
}

class BankAccount {
    double bal;
    double prevTrans;
    String customerName;
    String customerId;

    BankAccount(String customerName, String customerId) {
        this.customerName = customerName;
        this.customerId = customerId;
    }

    void deposit(double amount) {
        if (amount != 0) {
            bal += amount;
            prevTrans = amount;
            System.out.println("Successfully deposited: " + amount);
        } else {
            System.out.println("Invalid deposit amount");
        }
    }

    void withdraw(double amt) {
        if (amt != 0 && bal >= amt) {
            bal -= amt;
            prevTrans = -amt;
            System.out.println("Successfully withdrawn: " + amt);
        } else if (bal < amt) {
            System.out.println("Bank balance insufficient");
        } else {
            System.out.println("Invalid withdrawal amount");
        }
    }

    void getPreviousTrans() {
        if (prevTrans > 0) {
            System.out.println("Deposited: " + prevTrans);
        } else if (prevTrans < 0) {
            System.out.println("Withdrawn: " + Math.abs(prevTrans));
        } else {
            System.out.println("No transaction occurred");
        }
    }

    void menu() {
        char option;
        Scanner sc = new Scanner(System.in);
        do {
            System.out.println("\nWelcome " + customerName);
            System.out.println("Your ID: " + customerId);
            System.out.println("\n===== Bank Menu =====");
            System.out.println("a) Check Balance");
            System.out.println("b) Deposit Money");
            System.out.println("c) Withdraw Money");
            System.out.println("d) View Previous Transaction");
            System.out.println("e) Exit");
            System.out.print("Enter your option: ");
            option = sc.next().charAt(0);

            switch (option) {
                case 'a':
                case 'A':
                    System.out.println("Current Balance: " + bal);
                    break;
                case 'b':
                case 'B':
                    System.out.print("Enter amount to deposit: ");
                    double depositAmt = sc.nextDouble();
                    deposit(depositAmt);
                    break;
                case 'c':
                case 'C':
                    System.out.print("Enter amount to withdraw: ");
                    double withdrawAmt = sc.nextDouble();
                    withdraw(withdrawAmt);
                    break;
                case 'd':
                case 'D':
                    getPreviousTrans();
                    break;
                case 'e':
                case 'E':
                    System.out.println("Thank you for using our bank services!");
                    break;
                default:
                    System.out.println("Invalid option, please try again");
            }
        } while (option != 'e' && option != 'E');
        sc.close();
    }
}

关键修正点 #

• 补全完整菜单选项，用do-while循环实现菜单持续显示，直到用户选择退出
• 添加switch语句处理用户输入，调用对应的deposit、withdraw等功能方法
• 补全所有缺失的大括号，修复语法错误
• 给deposit和withdraw方法添加无效输入提示，增强用户体验
• 支持大小写选项输入，提升易用性

内容的提问来源于stack exchange，提问作者grzurmum