问题描述
我正在创建 BankAccount 类，但是当我运行此代码时，新输入似乎没有添加到 ArrayList。我想我正确地制作了 addaccount 方法，但它不起作用，所以你能告诉我我哪里错了。如果传递给构造函数的帐号不是 4 位数字，我还被要求创建构造函数以抛出带有适当消息的 BankAccountException 并抛出带有适当消息的 BankAccountException，如果initialBalance 小于零。但是，我们如何使用相同的异常抛出多个异常？请告诉我是否遗漏了一些信息。
Bank.java
import java.util.ArrayList;
public class Bank {
private ArrayList<BankAccount> accounts;
public Bank()
{
accounts = new ArrayList<BankAccount>();
}
public void addAccount(BankAccount a)
{
accounts.add(a);
}
public double getTotalBalance()
{
double total = 0;
for(BankAccount a : accounts)
{
total = total + a.getBalance();
}
return total;
}
/**
Counts the number of bank accounts whose balance is at least a given value.
@param atLeast the balance required to count an account
@return the number of accounts having least the given balance
*/
public int count(double atLeast)
{
int matches = 0;
for(BankAccount a : accounts)
{
if (a.getBalance() >= atLeast)
matches++;
}
return matches;
}
/**
Finds a bank account with a given number.
@param accountNumber the number to find
@return the account with the given number,or null if there is no such account
*/
public BankAccount find(int accountNumber)
{
for(BankAccount a : accounts)
{
if (a.getAccountNumber() == accountNumber)
return a;
}
return null;
}
public BankAccount deposit(int accountNumber,double amounts,double balance)
{
for(BankAccount a : accounts)
{
if(a.getAccountNumber() == accountNumber)
{
a.deposit(amounts);
System.out.println("Amount deposited : "+ balance); //amount deposited
}
}
return null;
}
public BankAccount withdraw(int accountNumber,double balance)
{
for(BankAccount a : accounts)
{
if(a.getAccountNumber() == accountNumber)
{
a.withdraw(amounts);
System.out.println("Amount withdrawn : "+ balance); //amount deposited
}
}
return null;
}
/**
Gets the bank account with the largest balance.
@return the account with the largest balance,or nullpointerexception if the bank has no accounts
*/
public BankAccount getMaximum()
{
if (accounts.size() == 0)
{
throw new NullPointerException("the bank has no accounts");
}
BankAccount largest = accounts.get(0);
for (int i = 1; i < accounts.size(); i++)
{
BankAccount a = accounts.get(i);
if (a.getBalance() > largest.getBalance())
largest = a;
}
System.out.println("largest balance of BankAccount: "+ largest);
return largest;
}
/**
Gets the bank account with the smallest balance.
@return the account with the smallest balance,or nullpointerexception if the bank has no accounts
*/
public BankAccount getMinimum()
{
if (accounts.size() == 0)
{
throw new NullPointerException("the bank has no accounts");
}
BankAccount smallest = accounts.get(0);
for (int i = 1; i < accounts.size(); i++)
{
BankAccount a = accounts.get(i);
if (a.getBalance() < smallest.getBalance())
smallest = a;
}
System.out.println("smallest balance of BankAccount: "+ smallest);
return smallest;
}
public String toString()
{
return "Bank " + accounts.toString();
}
}
BankAccount.java
import java.io.IOException;
public class BankAccount {
private static double balance;
private static int accountNumber;
public BankAccount(int anAccountNumber)throws IOException
{
IOException exception1 = new IOException("account number is not 4 digits");
IOException exception2 = new IOException("initial balance is less than 0");
accountNumber = anAccountNumber;
balance = 0;
}
public BankAccount(int anAccountNumber,double initialBalance){
balance = initialBalance;
accountNumber = anAccountNumber;
}
public double getBalance() {
return balance;
}
public int getAccountNumber(){
return accountNumber;
}
public void deposit(double amount){
balance += amount;
}
public void withdraw(double amount)throws RuntimeException
{
balance -= amount;
if(balance<0)
{
throw new RuntimeException("The balance becomes zero");
}
}
@Override
public String toString(){
return "Account Number: " + accountNumber + " balance: " + balance;
}
}
BankAccountException.java
public class BankAccountException extends RuntimeException
{
public BankAccountException(){}
public BankAccountException(String message){
super(message);
}
}
BankException.java
public class BankException extends RuntimeException
{
public BankException(){ }
public BankException(String message){
super(message);
}
}
BankTester.java
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
public class BankTester {
public static void main(String[] args) throws IOException {
//Read user input using scanner
Scanner sc=new Scanner(system.in);
int choice=0;
//Create Bank object
Bank Bank=new Bank();
//Loop until user quits
while(choice!=7)
{
System.out.println("Menu\n1. Add a new BankAccount to the Bank\n2. Get the balance of a BankAccount based on the account number.\n3. " +
"Deposit money to an existing BankAccount\n4. Withdraw money from an existing BankAccount"
+ "\n5. Find a BankAccount with the highest balance\n6. Find a BankAccount with the lowest balance\n7. Quit");
System.out.print("Enter your choice(or 7 to quit): ");
choice=sc.nextInt();
sc.nextLine();
switch(choice)
{
//Add a new BankAccount to the Bank
case 1:
try
{
System.out.print("Enter the account number: ");
int accountNumber = sc.nextInt();
if (accountNumber < 1000 || accountNumber > 9999)
{
throw new IOException("Account Number is invalid!");
}
System.out.println("Enter the initial balance: ");
double initial = sc.nextDouble();
if(initial<0)
{
throw new RuntimeException("initial balance is less than 0");
}
BankAccount a = new BankAccount(accountNumber,initial);
Bank.addAccount(a);
System.out.println("BankAccount added successfully!");
}
catch(IOException exception)
{
System.out.println("Account Number is invalid!");
}
catch(RuntimeException exception)
{
System.out.println("initial balance is less than 0");
}
break;
case 2:
//Get the balance of a BankAccount based on the account number
try {
System.out.print("Enter the account number: ");
int num = sc.nextInt();
sc.nextLine();
//Student number starts with 1000
if (num < 1000 || num > 9999)
{
throw new IOException("Account Number is invalid!");
} else
{
BankAccount x = Bank.find(num);
if (x != null)
{
System.out.println("Account infomation: \n" + x.toString());
}
else
{
throw new NullPointerException("The Bank dosen't have such a account");
}
}
}
catch(IOException exception)
{
System.out.println("Account Number is invalid");
}
catch(NullPointerException exception)
{
System.out.println("The Bank dosen't have such a account");
}
break;
case 3:
//Deposit money to an existing BankAccount
try
{
System.out.print("Enter Account Number: ");
int num=sc.nextInt();
sc.nextLine();
//Student number starts with 1000
if(num < 1000 || num > 9999)
{
throw new IOException("Account Number is invalid!");
}
else
{
BankAccount x = Bank.find(num);
if (x != null)
{
System.out.println("Enter the amount of money you want to deposit");
double amounts = sc.nextDouble();
double balance = x.getBalance();
Bank.deposit(num,amounts,balance);
}
else
{
throw new NullPointerException("The Bank doesn't have such a account");
}
}
}
catch(IOException exception)
{
System.out.println("Account Number is invalid");
}
catch(NullPointerException exception)
{
System.out.println("The Bank doesn't have such a account");
}
break;
case 4:
//Withdraw money from an existing BankAccount
try {
System.out.print("Enter Account Number: ");
int num = sc.nextInt();
sc.nextLine();
//Student number starts with 1000
if (num < 1000 || num > 9999) {
throw new IOException("Account Number is invalid!");
} else {
BankAccount x = Bank.find(num);
if (x != null)
{
System.out.println("Enter the amount of money you want to withdraw");
double amounts = sc.nextDouble();
double balance = x.getBalance();
Bank.withdraw(num,balance);
}
else
{
throw new NullPointerException("The Bank doesn't have such a account");
}
}
}
catch(NullPointerException exception)
{
System.out.println("The Bank doesn't have such a account");
}
catch(IOException exception)
{
System.out.println("Account Number is invalid");
}
catch(RuntimeException exception)
{
System.out.println("The balance becomes less than zero");
}
break;
case 5:
//Find a BankAccount with the highest balance
try
{
double atLeast = 0;
Bank.count(atLeast);
Bank.getMaximum();
}
catch(NullPointerException exception)
{
System.out.println("the bank has no accounts");
}
break;
case 6:
//Find a BankAccount with the lowest balance
try
{
Bank.getMinimum();
}
catch(NullPointerException exception)
{
System.out.println("the bank has no accounts");
}
break;
case 7:
System.out.println("End");
break;
default:
System.out.println("Invalid choice! Please retry!");
}
}
sc.close();
}
}
解决方法
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