Java如何創建唯一的對象名稱？

Question

如何在每次用戶要創建新帳戶時創建唯一對象？

例如，如果用戶使得如果用戶發出另一個帳戶我想命名對象ACC2我想命名ACC1然後對象的帳戶。 Account ac = new Account(input.nextInt(),0,0);。這是我需要它發生的地方。

我試着保持代碼儘可能簡單，也注意到我對java很陌生，這是一個個人項目，只是爲了學習。

System.out.println("Welcome to JAVA Bank"); 
    System.out.println("____________________"); 
    System.out.println("Plese Choose an Option: "); 
    System.out.println(""); 
    System.out.println("(1) New Account"); 
    System.out.println("(2) Enter Existing Account"); 



    int choice = input.nextInt(); 


    switch(choice){ 

     case 1: 
      System.out.println("Please choose an Account ID#"); 
      Account ac = new Account(input.nextInt(),0,0); 
      break; 




public class Account { 

private int id = 0; 
private double balance = 0; 
private double annualInterestRate = 0; 
private Date dateCreated; 

public Account(int id, double balance, double annualInterestRate) { 
    this.id = id; 
    this.balance = balance; 
    this.annualInterestRate = annualInterestRate; 
    this.dateCreated = new Date(); 

} 

幫助表示感謝你。

Answer 1

如果您想要一種識別多個帳戶的獨特方式，可能需要使用HashMap。 HashMap存儲每個鍵唯一的鍵值對。

創建一個類級別的變量來存儲賬戶：

Map<String, Account> accounts = new HashMap<String, Account>(); 

創建/加入帳戶的HashMap：

case 1: 
    System.out.println("Please choose an Account ID#"); 
    int accountID = input.nextInt(); //Get the requested ID 
    if (accounts.containsKey("acc"+accountID) //Check to see if an account already has this ID (I added acc to the start of each account but it is optional) 
    { 
     //Tell user the account ID is in use already and then stop 
     System.out.println("Account: " + accountID + " already exists!"); 
     break; 
    } 

     //Create account and add it to the HashMap using the unique identifier key 
     Account ac = new Account(input.nextInt(),0,0); 
     accounts.put("acc"+accountID, ac);