我正在创建一个银行系统项目。
我希望用户能够使用扫描仪中的accountid删除银行帐户。 我遇到麻烦，因为我试图移动，例如首先是accountid（123），second accountid（999），它将始终删除最后创建的帐户。
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package mainsample;
import java.util.*;
/**
*
* @author Khalid
*/
public class MainSample {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
BankProcess bankProcess = new BankProcess();
TransactionProcess transactionProcess = new TransactionProcess();
Bank bank = new Bank();
BankAccount bankAccount = new BankAccount();
int input = 0;
int selection = 0;
while (true) {
System.out.println("");
System.out.println("######## MENU ########");
System.out.println("[1] Create an account");
System.out.println("[2] Print all existing accounts");
System.out.println("[3] Delete an account");
System.out.println("[4] Deposit");
System.out.println("[5] Withdraw");
System.out.println("[6] Print transactions");
System.out.println("[0] Exit");
System.out.println("######################");
System.out.println("Please choose one of the following: ");
selection = scan.nextInt();
switch (selection) {
case 0:
System.out.println("Exit Successful");
System.exit(0);
break;
case 1:
System.out.println("'[1] Create an account' has been selected.");
System.out.print("Account Id: ");
int accountId = scan.nextInt();
scan.nextLine();
System.out.print("Holder Name: ");
String holderName = scan.nextLine();
System.out.print("Holder Address: ");
String holderAddress = scan.nextLine();
System.out.print("Opening Balance: ");
double openingBalance = scan.nextDouble();
System.out.print("Open Date: ");
String openDate = scan.next();
bankAccount = new BankAccount(accountId, holderName, openingBalance, holderAddress, openDate);
bank.setAccounts(bankProcess.openNewAccount(bank.getAccounts(), bankAccount));
System.out.println("Successfully Added.");
break;
case 2:
System.out.println("'[2] Display all existing accounts' has been selected");
System.out.println("-----------------------------------------------------");
bank.getAccounts().forEach((i, b) - > System.out.println(b));
System.out.println("-----------------------------------------------------");
break;
case 3:
System.out.println("[3] Delete an account has been selected");
System.out.println("Enter the account ID: ");
int accountNo = scan.nextInt();
bank.removeAccounts(bankProcess.removeAccount(bank.getAccounts(), bankAccount));
break;
case 4:
System.out.println("[4] Deposit has been selected");
System.out.println("Enter account ID: ");
int accountNumber = scan.nextInt();
System.out.println("Enter deposit amount: ");
double depositAmount = scan.nextDouble();
transactionProcess.deposit(bankAccount, depositAmount);
System.out.println(depositAmount + " has been deposited.");
break;
case 5:
System.out.println("[5] Withdraw has been selected");
System.out.println("Enter account ID: ");
int accountNu = scan.nextInt();
System.out.println("Enter withdraw amount: ");
double withdrawAmount = scan.nextDouble();
transactionProcess.withdraw(bankAccount, withdrawAmount);
System.out.println(withdrawAmount + " has been withdrawed.");
break;
case 6:
System.out.println("[6] Print Transaction has been selected");
System.out.println("Enter account ID: ");
int accountN = scan.nextInt();
break;
default:
System.out.println("Your choice was not valid!");
}
}
}
}
-
package mainsample;
import java.util.*;
/**
*
* @author Khalid
*/
public class Bank {
private TreeMap < Integer, BankAccount > bankAccounts = new TreeMap < Integer, BankAccount > ();
public TreeMap < Integer, BankAccount > getAccounts() {
return bankAccounts;
}
public void setAccounts(TreeMap < Integer, BankAccount > accounts) {
this.bankAccounts = accounts;
}
public BankAccount getAccount(Integer accountNumber) {
return bankAccounts.get(accountNumber);
}
public void removeAccounts(TreeMap < Integer, BankAccount > accounts) {
this.bankAccounts = accounts;
}
}
-
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package mainsample;
import java.util.*;
/**
*
* @author Khalid
*/
public class BankAccount {
private int accountId;
private String holderName;
private String holderAddress;
private String openDate;
private double currentBalance;
private List < Transaction > transactions = new ArrayList < Transaction > ();
//Provide Blank Constructor
public BankAccount() {}
//Constructor with an arguments.
public BankAccount(int accountNum, String holderNam, double currentBalance, String holderAdd, String openDate) {
this.accountId = accountNum;
this.holderName = holderNam;
this.holderAddress = holderAdd;
this.openDate = openDate;
this.currentBalance = currentBalance;
}
// Always Provide Setter and Getters
public int getAccountId() {
return accountId;
}
public void setAccountId(int accountId) {
this.accountId = accountId;
}
public String getHolderName() {
return holderName;
}
public void setHolderName(String holderName) {
this.holderName = holderName;
}
public String getHolderAddress() {
return holderAddress;
}
public void setHolderAddress(String holderAddress) {
this.holderAddress = holderAddress;
}
public String getOpenDate() {
return openDate;
}
public void setOpenDate(String openDate) {
this.openDate = openDate;
}
public double getCurrentBalance() {
return currentBalance;
}
public void setCurrentBalance(double currentBalance) {
this.currentBalance = currentBalance;
}
public List < Transaction > getTransactions() {
return transactions;
}
public void setTransactions(List < Transaction > transactions) {
this.transactions = transactions;
}
public String toString() {
return "\nAccount number: " + accountId + "\nHolder's name: " + holderName + "\nHolder's address: " + holderAddress + "\nOpen Date: " + openDate + "\nCurrent balance: " + currentBalance;
}
}
-
import java.util.*;
/**
*
* @author Khalid
*/
public class BankProcess {
// return the Updated list of BankAccounts
public TreeMap<Integer,BankAccount> openNewAccount(TreeMap<Integer,BankAccount> bankAccounts,BankAccount bankAccount) {
//Get the List of existing bank Accounts then add the new BankAccount to it.
bankAccounts.put(bankAccount.getAccountId(), bankAccount);
return bankAccounts;
}
public TreeMap<Integer,BankAccount> removeAccount(TreeMap<Integer,BankAccount> bankAccounts,BankAccount bankAccount) {
bankAccounts.remove(bankAccount.getAccountId(), bankAccount);
return bankAccounts;
}
}
答案 0 :(得分：0)
您问题的简单解决方案是，您根本不会计算要删除的帐户。
从你的案例3开始：
int accountNo = scan.nextInt();
bank.removeAccounts(bankProcess.removeAccount(bank.getAccounts(), bankAccount));
break;
您可以从命令行获取帐号no accountNo，然后您就不会执行任何操作。您只需使用之前设置为bankAccount的值调用removeAccount。由于您之前确实添加了一些帐户，因此您只需删除最后添加的帐户即可。
对于那些想知道为什么编译的人：
Map接口定义了自Java 8以来的remove（Object，Object）方法，请参见此处：java.util.Map#remove(Object, Object)
它基本上确保只有在获得给定值时才从地图中删除密钥。