我有一个小型ATM程序，我正在使用异常处理。我在我的程序开始时尝试捕获，它将把它发送到程序底部的异常处理。
用户输入一个5位数字...例如：12345。 然后它去检查号码，我检查用户号码是否＆lt; 5然后发送错误，但我想要它做的是检查长度是否＆lt;或者＆gt;然后发送错误。这是我的程序现在的代码......
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(input.nextInt() == 5)
{
System.out.println("Works!");
}
else{
throw new invalidNumber("invalid number");
}
}
public static void main(String args[])
{
BankMain myAtm = new BankMain();
myAtm.startAtm();
}
}
答案 0 :(得分：1)
将数字转换为字符串，然后使用length()检查位数
答案 1 :(得分：1)
实际上，你的程序应该挂起（你没有在你的问题中指明这个，所以我的假设可能不正确）。您正在调用input.nextInt()两次，这将使您的程序期望您的用户使用两组数字。
要解决此问题，我建议您首先使用nextLine()方法将用户输入作为字符串读取。然后，你会做这样的事情：
String userInput = input.nextLine().trim();
checkNumber(userInput);
cardNum.add(Integer.parseInt(userInput);
此外，由于我们现在正在读取整行，因此checkNumber将失败，因此您必须进行以下更改：
答案 2 :(得分：1)
System.out.println("Please select a 5 digit card number");
String s=input.next();
//Here check the nu. digits by using length()
cardNum.add(s);
checkNumber();
答案 3 :(得分：0)
你需要获取整个代码然后检查它的长度，如果它= = 5，你需要使用以下命令将输入转换为字符串：
String.valueOf(int i)
或
Integer.toString(int i)
或者只是使用：
将其读作字符串string givenCode = yourScan.next();
然后检查长度：
if (givenCode.length() == 5)