用java写一个银行存取款系统

要用Java编写一个银行存取款系统，你可以使用面向对象的编程思想来实现。首先，你可以创建一个BankAccount类来代表银行账户。这个类可以包含账户的属性，比如账户号码和余额，以及相关的方法，如存款、取款和查询余额。在存款和取款方法中，你可以根据用户输入的金额来更新账户的余额。

在程序的主函数中，你可以通过创建一个BankAccount对象来管理用户的账户。你可以使用循环和条件语句来实现一个简单的用户界面，让用户选择不同的操作类型，并根据用户的选择执行相应的操作。

以下是一个简单的示例代码，用于实现一个银行存取款系统：

import java.util.Scanner;

public class BankAccount {
    private String accountNumber;
    private double balance;

    public BankAccount(String accountNumber) {
        this.accountNumber = accountNumber;
        this.balance = 0.0;
    }

    public void deposit(double amount) {
        balance += amount;
    }

    public void withdraw(double amount) {
        if (amount <= balance) {
            balance -= amount;
        } else {
            System.out.println("Insufficient balance.");
        }
    }

    public double getBalance() {
        return balance;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        BankAccount account = new BankAccount("123456789");

        int choice;
        do {
            System.out.println("Bank Account Management System");
            System.out.println("1. Deposit");
            System.out.println("2. Withdraw");
            System.out.println("3. Check Balance");
            System.out.println("0. Exit");
            System.out.print("Enter your choice: ");

            choice = scanner.nextInt();

            switch (choice) {
                case 1:
                    System.out.print("Enter the deposit amount: ");
                    double depositAmount = scanner.nextDouble();
                    account.deposit(depositAmount);
                    System.out.println("Deposit successful.");
                    break;
                case 2:
                    System.out.print("Enter the withdrawal amount: ");
                    double withdrawalAmount = scanner.nextDouble();
                    account.withdraw(withdrawalAmount);
                    System.out.println("Withdrawal successful.");
                    break;
                case 3:
                    System.out.println("Current balance: " + account.getBalance());
                    break;
                case 0:
                    System.out.println("Exiting...");
                    break;
                default:
                    System.out.println("Invalid choice. Please try again.");
                    break;
            }
        } while (choice != 0);

        scanner.close();
    }
}