Question

你好，
我正在为银行门户网站编写代码，但遇到了一个令人毛骨悚然的错误。我有一个 login（）函数，该函数通过主函数中存在的switch case进行调用。但是只要我输入登录详细信息并登录即使条件为真，我的else部分也会被执行。能否请您检查有什么问题。我是Java编程的初学者。
我也很想听听关于我应该在此代码中添加哪些新功能的一些建议。
另外，请评价我代码的质量，我希望收到您的来信。

package e.banksolutions;
import java.util.Scanner;
import java.util.Random;
import java.util.Date;
public class EBankSolutions {

    long accountNumber;            // Variable for Storing account number
    long accountNumberGenerator=0000;   // Variable for generating and assigning account number
    String AccountHolderName;     // Variable for Storing account holder name
    String AccountType;           // Variable for Storing account type in string
    int AccTypeNumVal;
    long accountBalance;          // Variable to Store Current Account Balance. 
    String password;                //27-06-2018
    //----------------------------------------------------------------------------//

public void createAccount() throws InterruptedException
{
    Random rand = new Random();
    Scanner scan = new Scanner(System.in); // Scanner variable for accepting value from user
    System.out.println("----------------Welcome to Account Creation Portal-------------------");
    //accountNumberGenerator++; //Incrementing the account number generator var
    accountNumber=rand.nextInt(1000);; //assigning the account number
    System.out.println("Enter Your Name(Without Space Between Name) : ");
    AccountHolderName=scan.next();
    System.out.println("Enter New Password : ");                //27-06-2018
    password=scan.next();                                       //27-06-2018
    System.out.println("Enter Your Account Type Savings/Current");
    AccountType=scan.next();

   /* if(AccountType == "Savings"){
        AccTypeNumVal=1;
    }
    else if(AccountType == "Current"){
        AccTypeNumVal=2;
    }*/

bal:System.out.println("Enter your starting balance : ");
    accountBalance=scan.nextLong();
    if(accountBalance<5000){
        System.out.println("Oops!!! Your Account balance should be minimum 5000 or more.\nYou need to fill the form again.");
        System.exit(0);
    }

    System.out.println("Account Created Successfully.\nYour Account Number is: "+accountNumber+" Please Note it Down.");
    System.out.println("------------------------------------------------------------");
    //Delay code below
    Thread.sleep(5000);
    System.out.flush();
}

public void DisplayAccount() throws InterruptedException
{
    System.out.println("Displaying Account Information for Account Number : "+accountNumber);
    System.out.println("------------------------------------------------------------");
    System.out.println("Account Number  : "+accountNumber);
    System.out.println("Account Name    : "+AccountHolderName);
    System.out.println("Account Type    : "+AccountType);
    System.out.println("Account balance : "+accountBalance);
    System.out.println("Your Password   : _Hidden_"); //27-06-2018
    System.out.println("------------------------------------------------------------");
    Thread.sleep(5000);
    System.out.flush();
}

public void DepositAmount() throws InterruptedException
{
    Scanner scan = new Scanner(System.in); // Scanner variable for accepting value from user
    long depositAmt;
    System.out.println("---------------Welcome to Deposit Portal----------------");
    System.out.println("You are Depositing amount for Account Number: "+accountNumber);
    System.out.println("\nEnter the Amount to Deposit : ");
    depositAmt=scan.nextLong();
    accountBalance=accountBalance+depositAmt;
    System.out.println("Amount Deposited Successfully.. \nUpdated Balance: "+accountBalance);
    System.out.println("------------------------------------------------------------");
    Thread.sleep(5000);
    System.out.flush();
}


public void WithdrawAmount() throws InterruptedException
{
    Scanner scan = new Scanner(System.in); // Scanner variable for accepting value from user
    long withdrawAmt;
    System.out.println("---------------Welcome to Deposit Portal----------------");
    System.out.println("You are Withdrawing amount for Account Number: "+accountNumber);
    System.out.println("\nEnter the Amount to Withdraw : ");
    withdrawAmt=scan.nextLong();
    accountBalance=accountBalance-withdrawAmt;
    System.out.println("Amount Withdrawn Successfully.. \nUpdated Balance: "+accountBalance);
    System.out.println("------------------------------------------------------------");
    Thread.sleep(5000);
    System.out.flush();
}

public void login() throws InterruptedException
{
    int ch=0;
    Scanner scan = new Scanner(System.in);
    long accNum=0;
    String passWd="0";
    System.out.println("Enter Account Number : ");
    accNum=scan.nextLong();
    System.out.println("Enter Your Password  : ");
    passWd=scan.next();           
    if (accNum==accountNumber && passWd==password) {
        System.out.println("Logged In Successfully with account number: "+accountNumber+"\n-------------------------------------");   
        System.out.println("Choose Option Number From Below Menu");
        System.out.println("1.Deposit Amount\n2.Withdraw Amount\n3.Display Account Info\n4.Close Account\n5.Exit");
        switch(ch)
        {
            case 1: DepositAmount();
                    break;
            case 2: WithdrawAmount();
                    break;
            case 3: DisplayAccount();
                    break;
            case 4: System.out.println("You cannot close your account. Feature Coming Soon...");
                    break;
            case 5: System.exit(0);
                    break;
        }
    } 
    else if(accNum!=accountNumber && passWd!=password) {
        System.out.println("You have Entered Incorrect Account Number or Password. Please Check Again.");
        Thread.sleep(5000);
        System.out.flush();
        System.exit(0);
    }
    else{
        System.out.println("Unknown Error Occured. Try Agian Later");
        Thread.sleep(5000);
        System.out.flush();
        System.exit(0);
    }
}


EBankSolutions()
{
    accountNumber=0000;
    AccountHolderName="UNDEFINED";
    AccountType="UNDEFINED";
    accountBalance=0000;
    accountNumberGenerator=0000;
    AccTypeNumVal=9;
}

public static void main(String[] args) throws InterruptedException {
    Scanner scan = new Scanner(System.in); // Scanner variable for accepting value from user
    EBankSolutions a1 = new EBankSolutions();
    int ch;
    int i=0;
    System.out.println("Welcome to Bank E Portal\n");
   while(i!=5)
   {
    System.out.println("Select any Choice Number From below menu...");
    System.out.println("1. Create Account\n2. Login\n3. Exit Portal");
    System.out.print("Enter Your Choice Code 1-4: ");
    ch=scan.nextInt();
    switch(ch)
    {
        case 1: a1.createAccount();
                break;

        case 2: a1.login();
                break; 

        case 3: System.exit(0);
                break;

    }

   }
}

}

Answer 1

有几个问题使登录功能无法正常工作。首先，您在检查密码时正在检查string equality with ==。这是行不通的，因为在Java中，字符串是对象而不是基元。

接下来，当您似乎打算将其扫描为密码时，使用扫描仪扫描至passWd。在您的版本中，密码始终为空。

通过这些更改，您的功能将如下所示：

public void login() throws InterruptedException
{
    //snip
    System.out.println("Enter Your Password  : ");
    password=scan.next();           
    if (accNum==accountNumber && passWd.equals(password)) {
        //snip
    }
}

Answer 2

在Java字符串中，对象不能用有意义的方式用==比较两个对象。您必须始终使用equals方法。当您使用==检查相等性时，它将检查两个变量是否指向同一对象。

您必须更改if (accNum==accountNumber && passWd==password)

到if (accNum==accountNumber && passWd.equals(password))

Answer 3

“ ch”的值从哪里来？

您打印选项列表，但在任何时候都看不到用户的答复。

Java程序逻辑错误。 IF..Part不起作用/正在执行

3 个答案: