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Learn how to create a Java program that validates passwords based on specific conditions, focusing on checking if the password ends with `two different digits`.
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How to Validate if a Password Ends with Two Different Digits Using Java Regular Expressions

In our increasingly digital world, ensuring the security of our online accounts is more important than ever. A strong password is the first line of defense against unauthorized access. In this guide, we will walk you through the process of creating a Java program that validates passwords based on specific criteria, with a particular focus on checking if the password ends with two different digits.

The Password Validation Criteria

Before we delve into the solution, let's outline the requirements for a valid password:

Length: At least 5 characters long and at most 12 characters long.

Uppercase Start: Must start with an uppercase letter.

Different Digits: Must end with two different digits.

Special Characters: Must include at least one special character from the set: !"# $%&'()*+ -.

Lowercase Letter: Must include at least one lowercase letter.

With these criteria in mind, let's take a closer look at how to implement the validation for the requirement that the password must end with two different digits using regular expressions.

Understanding Regular Expressions

Regular expressions (regex) are powerful tools for matching patterns in strings. In our case, we will use regex to ensure that the password meets our specific criteria, particularly the requirement for the password to end with two different digits.

Suggested Regex Pattern

For our second condition, the regex pattern we can use is:

[[See Video to Reveal this Text or Code Snippet]]

This pattern checks for the presence of various required elements in the password while ensuring that the last two characters are different digits.

Breakdown of the Regex Pattern

Let’s dissect the regex pattern to better understand how it validates each password condition:

^: Asserts the start of the password string.

(?=.*[a-z]): Ensures at least one lowercase letter is present anywhere in the password.

(?=.[!"# $%&'()+ -]): Ensures at least one special character from the specified set is present anywhere in the password.

[A-Z]: The password must start with an uppercase letter.

.{2,9}: Follows the uppercase letter by 2 to 9 characters, ensuring the total length is between 5 and 12 characters.

(\d): The second-to-last character in the password must be any digit, stored in a capturing group.

(?!\1)\d: Asserts that the last character is also a digit, but it must be different from the second-to-last character (using negative lookahead).

$: Asserts the end of the password string.

Implementing the Regex in Java

Now that we understand the regex pattern, let's see it in action within a Java program. Here’s a simple implementation:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Java Code

Scanner: We use the Scanner class to receive user input for the password.

isValid Method: This method uses the regex pattern to validate the password against our criteria.

Output: It prints "MATCH" if the password is valid according to our regex checks, and "NO MATCH" otherwise.

Conclusion

Creating a secure password is crucial in today's digital landscape, and using regular expressions in Java is an effective way to validate password criteria. By following the steps and understanding the regex we explored, you can enhance password security successfully. Remember to always strive for strong, unique passwords to safeguard your information!

Feel free to test and modify the regex pattern and logic to fit additional password validation rules you may have.