我做了一个ATM程序。我有一个尝试捕获器,它将要求用户输入其PIN码。密码必须是5位数字。因此,异常将检查它是否为5位数字,但异常处理无效。无论我输入什么数字,它总是显示无效数字。
这是我的代码,try catch在程序的顶部,而异常处理checkNumber在程序的底部。
import java.util.ArrayList;
import java.util.Scanner;
public class BankMain
{
private double availableBal = 80;
private double totalBal = 100;
private double availableBal2 = 480;
private double totalBal2 = 500;
private double availableBal3 = 80;
private double totalBal3 = 100;
ArrayList<Integer> cardNum = new ArrayList<Integer>();
static Scanner input = new Scanner(System.in);
private String error; // String the error from the exception
{
error = "error";
}
public void cardNumbers()
{
Scanner cards = new Scanner(System.in);
Scanner input = new Scanner(System.in);
Scanner keyboard = new Scanner(System.in);
try
{
System.out.println("Please select a 5 digit card number");
cardNum.add(input.nextInt());
checkNumber();
}
catch (invalidNumber err)
{
System.out.println("Caught Error: " + err.getError());
}
System.out.println("Thank you! You're card number is " + cardNum);
System.out.println("Type 'c' to go back to main menu.");
String value = keyboard.next();
if (value.equalsIgnoreCase("c"))
{
menu();
}
else if (!keyboard.equals('c'))
{
System.out.println("Invalid Entry!");
}
}
public void menu()
{
System.out.println("ATM Menu:");
System.out.println();
System.out.println("1 = Create Account");
System.out.println("2 = Account Login");
System.out.println("3 = Exit ATM");
query();
}
public void startAtm()
{
menu();
}
public void drawMainMenu()
{
AccountMain main3 = new AccountMain();
int selection;
System.out.println("\nATM main menu:");
System.out.println("1 - View account balance");
System.out.println("2 - Withdraw funds");
System.out.println("3 - Add funds");
System.out.println("4 - Back to Account Menu");
System.out.println("5 - Terminate transaction");
System.out.print("Choice: ");
selection = input.nextInt();
switch (selection)
{
case 1:
viewAccountInfo();
break;
case 2:
withdraw();
break;
case 3:
addFunds();
break;
case 4:
AccountMain.selectAccount();
break;
case 5:
System.out.println("Thank you for using this ATM!!! goodbye");
}
}
public void viewAccountInfo()
{
System.out.println("Account Information:");
System.out.println("\t--Total balance: $" + totalBal);
System.out.println("\t--Available balance: $" + availableBal);
drawMainMenu();
}
public void viewAccountInfo2()
{
System.out.println("Account Information:");
System.out.println("\t--Total balance: $" + totalBal2);
System.out.println("\t--Available balance: $" + availableBal2);
drawMainMenu();
}
public void deposit(int depAmount)
{
System.out.println("\n***Please insert your money now...***");
totalBal = totalBal + depAmount;
availableBal = availableBal + depAmount;
}
public void checkNsf(int withdrawAmount)
{
if (totalBal - withdrawAmount < 0)
System.out.println("\n***ERROR!!! Insufficient funds in you accout***");
else
{
totalBal = totalBal - withdrawAmount;
availableBal = availableBal - withdrawAmount;
System.out.println("\n***Please take your money now...***");
}
}
public void addFunds()
{
int addSelection;
System.out.println("Deposit funds:");
System.out.println("1 - $20");
System.out.println("2 - $40");
System.out.println("3 - $60");
System.out.println("4 - $100");
System.out.println("5 - Back to main menu");
System.out.print("Choice: ");
addSelection = input.nextInt();
switch (addSelection)
{
case 1:
deposit(20);
drawMainMenu();
break;
case 2:
deposit(40);
drawMainMenu();
break;
case 3:
deposit(60);
drawMainMenu();
break;
case 4:
deposit(100);
drawMainMenu();
break;
case 5:
drawMainMenu();
break;
}
}
public void withdraw()
{
int withdrawSelection;
System.out.println("Withdraw money:");
System.out.println("1 - $20");
System.out.println("2 - $40");
System.out.println("3 - $60");
System.out.println("4 - $100");
System.out.println("5 - Back to main menu");
System.out.print("Choice: ");
withdrawSelection = input.nextInt();
switch (withdrawSelection)
{
case 1:
checkNsf(20);
drawMainMenu();
break;
case 2:
checkNsf(40);
drawMainMenu();
break;
case 3:
checkNsf(60);
drawMainMenu();
break;
case 4:
checkNsf(100);
drawMainMenu();
break;
case 5:
drawMainMenu();
break;
}
}
public void query()
{
Scanner keyboard = new Scanner(System.in);
double input = keyboard.nextInt();
if (input == 2)
{
BankMainPart2 main2 = new BankMainPart2();
System.out.println("Please enter your 5 digit card number.");
BankMainPart2.loginCard(cardNum);
}
else if (input == 1)
{
cardNumbers();
}
else if (input == 3)
{
System.out.println("Thank you, have a nice day!");
System.exit(0);
}
}
public void checkingMenu()
{
AccountMain main3 = new AccountMain();
int selection;
System.out.println("\nATM main menu:");
System.out.println("1 - View account balance");
System.out.println("2 - Withdraw funds");
System.out.println("3 - Add funds");
System.out.println("4 - Back to Account Menu");
System.out.println("5 - Terminate transaction");
System.out.print("Choice: ");
selection = input.nextInt();
switch (selection)
{
case 1:
viewAccountInfo2();
break;
case 2:
withdraw();
break;
case 3:
addFunds();
break;
case 4:
AccountMain.selectAccount();
break;
case 5:
System.out.println("Thank you for using this ATM!!! goodbye");
}
}
private static void checkNumber() throws invalidNumber // run the check activation exception
{
if (String.valueOf(input).length() != 5)
{
throw new invalidNumber("invalid number");
}
else
{
System.out.println("Works!");
}
}
public static void main(String args[])
{
BankMain myAtm = new BankMain();
myAtm.startAtm();
}
}
最佳答案
为什么要拥有三个不同的Scanner类实例。这就是使程序令人困惑的原因。
在compareNumber()
方法中,您实际上是在检查input
的值,它是Scanner的一个实例。最好像这样使用它:-checkNumber(input.nextInt())
并将数字添加到checkNumber(int num)
方法的列表中。
当然,我并不是说这是一种很好的编码方式。但是它暂时可以解决您的问题。
否则,您的代码有很多问题。
这是您的try-catch块:-
try {
System.out.println("Please select a 5 digit card number");
cardNum.add(input.nextInt());
checkNumber();
} catch (invalidNumber err) {
System.out.println("Caught Error: " + err.getError());
}
这是您的
checkNumber()
方法:-private static void checkNumber() throws invalidNumber
{
if (String.valueOf(input).length() != 5) {
throw new invalidNumber("invalid number");
}
else {
System.out.println("Works!");
}
}
现在,您必须看到您正在使用
input
作为String.valueOf(input)
的参数。但是,您在try-catch块之前已将“ input”声明为Scanner的实例。
Scanner cards = new Scanner(System.in);
Scanner input = new Scanner(System.in);
Scanner keyboard = new Scanner(System.in);
这段代码在您的
codeNumbers()
方法中。因此,很明显,您的
input
永远不会真正包含用户输入,而是一个表示对象hashcode
的new Scanner(System.in)
。因此,最好将用户的整数输入传递给
checkNumber()
方法。************修改代码中需要。
因此,您的checkNumber()`将被修改为:-
private static void checkNumber(int number) throws invalidNumber
{
if (String.valueOf(number).length() != 5) {
throw new invalidNumber("invalid number");
}
else {
System.out.println("Works!");
}
}
在try-catch块中对该方法的调用将更改为:-
try {
System.out.println("Please select a 5 digit card number");
int number = input.nextInt();
cardNum.add(number);
checkNumber(number);
} catch (invalidNumber err) {
System.out.println("Caught Error: " + err.getError());
}