无法调用 String.equals(Object) [重复]

Question

private void login() throws UserException, NoSuchAlgorithmException, InvalidKeySpecException {
    System.out.println("=== Log in ===");
    while (true) {
        System.out.println("Enter your login \nor Enter EXIT for return to main menu ->");
        String inputLogin = this.sc.nextLine();
        if ("EXIT".equalsIgnoreCase(inputLogin)) {
            break;
        }
        try {
            User user = userImpl.read(inputLogin);
            if (user.getLogin() == null) {
                System.err.println("Username incorrect.");
            } else {
                System.out.println("Enter your password \n or Enter EXIT for return to main menu ->");
                String inputPassword = this.sc.nextLine();
                user = userImpl.readPassword(inputPassword);
                if (!user.getPassword().equals(generateStrongPasswordHash(inputPassword)) || "EXIT".equalsIgnoreCase(inputPassword)) {
                    System.err.println("Password incorrect");
                    continue;
                }
                System.out.println("Log in successfully✔✔✔");
            }
        } catch (UserException | NoSuchAlgorithmException | InvalidKeySpecException e) {
            e.printStackTrace();
        }
    }
}

我正在尝试使用 JDBC (MySQL) 实现控制台程序 Cinema。使用登录方法后，我得到了这个Exception。 如何在控制台应用上实现授权？ User User

Answer 1

似乎user.getPassword() 正在返回null。因此，我建议您在检查 user.getPassword().equals(generateStrongPasswordHash(inputPassword)) 之前检查 user.getPassword() === null。

private void login() throws UserException, NoSuchAlgorithmException, InvalidKeySpecException {
    System.out.println("=== Log in ===");

    while (true) {
        System.out.println("Enter your login \nor Enter EXIT for return to main menu ->");
        String inputLogin = this.sc.nextLine();

        if ("EXIT".equalsIgnoreCase(inputLogin)) {
            break;
        }

        try {
            User user = userImpl.read(inputLogin);

            if (user.getLogin() == null) {
                System.err.println("Username incorrect.");
            } else {
                System.out.println("Enter your password \n or Enter EXIT for return to main menu ->");
                String inputPassword = this.sc.nextLine();
                user = userImpl.readPassword(inputPassword);

                if (user.getPassword() === null || !user.getPassword().equals(generateStrongPasswordHash(inputPassword)) || "EXIT".equalsIgnoreCase(inputPassword)) {
                    System.err.println("Password incorrect");
                    continue;
                }

                System.out.println("Log in successfully✔✔✔");
            }
        } catch (UserException | NoSuchAlgorithmException | InvalidKeySpecException e) {
             e.printStackTrace();
        }
    }
}