The client is trying to withdraw funds that are no longer available (fraud). What will happen on the developer's side?

If a client attempts to withdraw funds they do not have (for example, a fraudulent attempt), the typical response from the developer is as follows:

• Balance validation: Before performing the operation, the system checks if there are sufficient funds in the client's account.
• Operation denial: If funds are insufficient, the transaction is rejected, and the client receives a corresponding notification.
• Logging and monitoring: The fraudulent attempt is recorded in logs for subsequent analysis.
• Security and alerting: Depending on security policies, security services may be notified or the account may be blocked.

Example of balance check in Java:

public void withdraw(User user, BigDecimal amount) {
    BigDecimal balance = accountService.getBalance(user);
    if (balance.compareTo(amount) < 0) {
        throw new InsufficientFundsException("Insufficient funds for withdrawal");
    }
    // proceed with withdrawal operation
}

Thus, the developer ensures protection against incorrect operations at the business logic and infrastructure levels.