如何使用 try 和 catch 块来生成自定义异常？

Question

y 如果用户 ID 为负，我需要生成异常。我试过了，但没有得到任何相关的结果文本

public void registerUser() {
        System.out.println("Please Enter your userId : ");
        int userId = sc.nextInt();
        boolean flag = true;
        for(User userdetails : listUsers) {
            if(userdetails.getUserId() == userId) {
                System.out.println("The deatils which you entered User is already present.pLease Login..");
                flag = false;
                break;
            }
        }
        
        if(flag) {
            System.out.println("Please Enter userName : ");
            String username = sc.next();
            System.out.println("Please enter your emailId : ");
            String emailId = sc.next();
            System.out.println("Enter your password : ");
            String password = sc.next();

            listUsers.add(new User(userId,username,emailId,password));
            System.out.println("user details added successfully..!");
        }
        

Answer 1

要在 Java 中抛出异常，您可以这样做：

throw new Exception("Exception message");

所以我想你想这样做：

if (userId < 0) {
   throw new Exception("UserId is negative");
}