Question

我在向arraylist添加对象时遇到问题，我似乎无法找到问题所在。当我添加新帐户时，它会删除上一个对象。请帮助！

public class bankmain {
    static File f=new File("C:/Users/Guest/workspace/bank.txt");
    private static ArrayList<Account> accountList = new ArrayList<>();
    private static Account selectedAccount;
    private static Account selectedAccount2;
    private static boolean flag = false;
    private static boolean fly=true;
    private static double amount;

    public static void main(String[] args) throws FileNotFoundException {
        Scanner input = new Scanner(System.in);
        Scanner scan = new Scanner(System.in);
        //readFile();    
        System.out.println("Enter the option for the operation you need:");
        System.out.println("1-List of accounts");
        System.out.println("2-Create new account");
        System.out.println("3-Delete account");
        System.out.println("4-Exit");
        System.out.println("5-Deposit");
        System.out.println("6-Withdraw");
        System.out.println("7-Transfer");
        while (fly) {
            int choice = input.nextInt();
            switch (choice) {
                case 1:
                // List
                for (int i = 0; i < accountList.size(); i++) {
                    System.out.println("Owner:"+accountList.get(i).getOwner()+"-Account Number:"+accountList.get(i).getAccNumber()+"-Balance:"+accountList.get(i).getBalance());
                }
                break;
                case 2:
                // Create
                int accNo;
                Double bal;
                String own;
                System.out.println("Enter owners name: ");
                own=scan.next();
                System.out.println("Enter account number: ");
                accNo = scan.nextInt();
                System.out.println("Enter initial balance: ");
                bal = scan.nextDouble();
                System.out.println("Owner:" + own+ " Balance:" + bal + " Account Number:"+accNo );
                Account k=new Account(bal, accNo, own);
                accountList.add(k);
                break;
            }
        }
    }
}

输入您需要的操作选项：

 1. List of accounts
 2. Create new account
 3. Delete account
 4. Exit
 5. Deposit
 6. Withdraw
 7. Transfer


Enter owners name: 

Anna

Enter account number: 

1

Enter initial balance: 

1200

Owner:Anna Balance:1200.0 Account Number:1

2

Enter owners name: 

Lana

Enter account number: 

2

Enter initial balance: 

3000

Owner:Lana Balance:3000.0 Account Number:2

1

Owner:Lana-Account Number:2-Balance:3000.0

Owner:Lana-Account Number:2-Balance:3000.0

Answer 1

你应该查看你的Account课程。您可能将属性声明为静态，这意味着所有Account实例都具有相同的属性。删除static关键字。

Answer 2

您的代码似乎没有问题。我已经运行了代码，我可以看到正确添加的帐户。这是Account class定义：

class Account {

    private double balance;
    private int accNumber;
    private String owner;

    public Account(Double bal, int accNo, String own) {
        // TODO Auto-generated constructor stub
        this.balance = bal;
        this.accNumber = accNo;
        this.owner = own;
    }

    public int getAccNumber() {
        return accNumber;
    }

    public void setAccNumber(int accNumber) {
        this.accNumber = accNumber;
    }

    public String getOwner() {
        return owner;
    }

    public void setOwner(String owner) {
        this.owner = owner;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }

    public double getBalance() {
        return balance;
    }

}

结果如下：

输入您需要的操作选项：

1 - 账户清单

2 - 创建新帐户

3 - 删除帐户

4-退出

5存款

-6-提款

7-转移

2

输入所有者名称：

艾伦

输入帐号：

1

输入初始余额：

10000

所有者：Alan Balance：10000.0帐号：1

2

输入所有者名称：

巴兰

输入帐号：

2

输入初始余额：

20000

所有者：Balan余额：20000.0帐号：2

2

输入所有者名称：

结肠

输入帐号：

3

输入初始余额：

3000

所有者：冒号余额：3000.0帐号：3

1

所有者：Alan-Account Number：1-Balance：10000.0

所有者：Balan-账号：2-Balance：20000.0

所有者：冒号 - 帐号：3 - 余额：3000.0

将对象添加到arraylist，银行帐户

2 个答案: