Say it once and only once TL;DR: Avoid duplicate email validations. Problems Addressed Repeated email validation logic in multiple places.
Risk of inconsistent validation rules.
Bijection violation
Primitive Obsession
Premature Optimization Related Code Smells https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-x-i7r34uj https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxv https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xiv https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxvi Code Smell 20 - Premature Optimization Steps Identify where email validation logic is duplicated.


Create an Email Address class to encapsulate validation rules.


Refactor code to use the Email Address class instead of raw strings. Sample Code Before public class Person {
    private String emailAddress;
    // Primitive Obsession

    public void setEmailAddress(String emailAddress) {
        // Duplicated code
        if (!emailAddress.matches(
            "^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.emailAddress = emailAddress;
    }
}

public class JobApplication {
    private String applicantEmailAddress;

    public void setApplicantEmailAddress(String emailAddress) {
        // Duplicated code
        if (!emailAddress.matches(
            "^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.applicantEmailAddress = emailAddress;
    }
} After public class EmailAddress {
    // 2. Create an `EmailAddress` class to encapsulate validation rules.
    private final String value;

    public EmailAddress(String value) {
        // The rules are in a single place
        // And all objects are created valid
        if (!value.matches("^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.value = value;
    }
}

public class Person {
    private final EmailAddress emailAddress;

    public Person(EmailAddress emailAddress) {
        // 1. Identify where email validation logic is duplicated.
        // 3. Refactor code to use the `Email Address`
        // class instead of raw strings.
        // No validation is required
        this.emailAddress = emailAddress;
    } 
}

public class JobApplication {
    private EmailAddress applicantEmailAddress;

    public JobApplication(EmailAddress applicantEmailAddress) {
        this.applicantEmailAddress = applicantEmailAddress;
    }
} Type [x]Semi-Automatic Safety This refactoring is safe if you replace all occurrences of raw email strings with the 'EmailAddress' class and ensure all tests pass. Why Is the Code Better? You make email validation consistent across your application. Since validation rules are centralized in one place, the code becomes easier to maintain. You also reduce the risk of bugs caused by inconsistent logic. In the real world, Email Addresses are small objects that exist and are not strings. The refactored code is closer to the real-world MAPPER. Notice that bijection names are essential. It would help to create an EmailAddress, not an Email, since the Email should map to the actual message. Don't let Premature Optimizators tell you this solution has a performance penalty. They never do actual benchmarks with real-world data. Refactor With AI Without Proper Instructions

With Specific Instructions



ChatGPT

ChatGPT



Claude

Claude



Perplexity

Perplexity



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Gemini

Gemini Tags Encapsulation Related Refactorings https://maximilianocontieri.com/refactoring-007-extract-class?embedable=true https://maximilianocontieri.com/refactoring-012-reify-associative-arrays?embedable=true https://hackernoon.com/improving-the-code-one-line-at-a-time?embedable=true Credits Image by Gerd Altmann on Pixabay This article is part of the Refactoring Series. How to Improve Your Code With Easy Refactorings Say it once and only once Say it once and only once TL;DR: Avoid duplicate email validations. TL;DR: Avoid duplicate email validations. Problems Addressed Repeated email validation logic in multiple places. Risk of inconsistent validation rules. Bijection violation Primitive Obsession Premature Optimization Repeated email validation logic in multiple places. Repeated email validation Risk of inconsistent validation rules. Bijection violation Bijection Primitive Obsession Primitive Obsession Premature Optimization Premature Optimization Related Code Smells https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-x-i7r34uj https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-x-i7r34uj https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxv https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxv https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xiv https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xiv https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxvi https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxvi Code Smell 20 - Premature Optimization Code Smell 20 - Premature Optimization Steps Identify where email validation logic is duplicated. Create an Email Address class to encapsulate validation rules. Refactor code to use the Email Address class instead of raw strings. Identify where email validation logic is duplicated. Identify where email validation logic is duplicated. Create an Email Address class to encapsulate validation rules. Create an Email Address class to encapsulate validation rules. Email Address Refactor code to use the Email Address class instead of raw strings. Refactor code to use the Email Address class instead of raw strings. Email Address Sample Code Before public class Person {
    private String emailAddress;
    // Primitive Obsession

    public void setEmailAddress(String emailAddress) {
        // Duplicated code
        if (!emailAddress.matches(
            "^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.emailAddress = emailAddress;
    }
}

public class JobApplication {
    private String applicantEmailAddress;

    public void setApplicantEmailAddress(String emailAddress) {
        // Duplicated code
        if (!emailAddress.matches(
            "^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.applicantEmailAddress = emailAddress;
    }
} public class Person {
    private String emailAddress;
    // Primitive Obsession

    public void setEmailAddress(String emailAddress) {
        // Duplicated code
        if (!emailAddress.matches(
            "^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.emailAddress = emailAddress;
    }
}

public class JobApplication {
    private String applicantEmailAddress;

    public void setApplicantEmailAddress(String emailAddress) {
        // Duplicated code
        if (!emailAddress.matches(
            "^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.applicantEmailAddress = emailAddress;
    }
} After public class EmailAddress {
    // 2. Create an `EmailAddress` class to encapsulate validation rules.
    private final String value;

    public EmailAddress(String value) {
        // The rules are in a single place
        // And all objects are created valid
        if (!value.matches("^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.value = value;
    }
}

public class Person {
    private final EmailAddress emailAddress;

    public Person(EmailAddress emailAddress) {
        // 1. Identify where email validation logic is duplicated.
        // 3. Refactor code to use the `Email Address`
        // class instead of raw strings.
        // No validation is required
        this.emailAddress = emailAddress;
    } 
}

public class JobApplication {
    private EmailAddress applicantEmailAddress;

    public JobApplication(EmailAddress applicantEmailAddress) {
        this.applicantEmailAddress = applicantEmailAddress;
    }
} public class EmailAddress {
    // 2. Create an `EmailAddress` class to encapsulate validation rules.
    private final String value;

    public EmailAddress(String value) {
        // The rules are in a single place
        // And all objects are created valid
        if (!value.matches("^[\\w.%+-]+@[\\w.-]+\\.[a-zA-Z]{2,}$")) {
            throw new IllegalArgumentException(
                "Invalid email address format");
        }
        this.value = value;
    }
}

public class Person {
    private final EmailAddress emailAddress;

    public Person(EmailAddress emailAddress) {
        // 1. Identify where email validation logic is duplicated.
        // 3. Refactor code to use the `Email Address`
        // class instead of raw strings.
        // No validation is required
        this.emailAddress = emailAddress;
    } 
}

public class JobApplication {
    private EmailAddress applicantEmailAddress;

    public JobApplication(EmailAddress applicantEmailAddress) {
        this.applicantEmailAddress = applicantEmailAddress;
    }
} Type [x]Semi-Automatic [x] Semi-Automatic [x] Safety This refactoring is safe if you replace all occurrences of raw email strings with the 'EmailAddress' class and ensure all tests pass. Why Is the Code Better? You make email validation consistent across your application. Since validation rules are centralized in one place, the code becomes easier to maintain. You also reduce the risk of bugs caused by inconsistent logic. In the real world, Email Addresses are small objects that exist and are not strings. Email Addresses small objects The refactored code is closer to the real-world MAPPER . MAPPER Notice that bijection names are essential. It would help to create an EmailAddress , not an Email , since the Email should map to the actual message. EmailAddress Email map Don't let Premature Optimizators tell you this solution has a performance penalty. Premature Optimizators They never do actual benchmarks with real-world data. Refactor With AI Without Proper Instructions

With Specific Instructions



ChatGPT

ChatGPT



Claude

Claude



Perplexity

Perplexity



Copilot

Copilot



Gemini

Gemini Without Proper Instructions

With Specific Instructions ChatGPT

ChatGPT Claude

Claude Perplexity

Perplexity Copilot

Copilot Gemini

Gemini Without Proper Instructions With Specific Instructions Without Proper Instructions Without Proper Instructions With Specific Instructions With Specific Instructions ChatGPT ChatGPT ChatGPT ChatGPT ChatGPT ChatGPT ChatGPT ChatGPT Claude Claude Claude Claude Claude Claude Claude Claude Perplexity Perplexity Perplexity Perplexity Perplexity Perplexity Perplexity Perplexity Copilot Copilot Copilot Copilot Copilot Copilot Copilot Copilot Gemini Gemini Gemini Gemini Gemini Gemini Gemini Gemini Tags Encapsulation Encapsulation Related Refactorings https://maximilianocontieri.com/refactoring-007-extract-class?embedable=true https://maximilianocontieri.com/refactoring-007-extract-class?embedable=true https://maximilianocontieri.com/refactoring-012-reify-associative-arrays?embedable=true https://maximilianocontieri.com/refactoring-012-reify-associative-arrays?embedable=true https://hackernoon.com/improving-the-code-one-line-at-a-time?embedable=true https://hackernoon.com/improving-the-code-one-line-at-a-time?embedable=true Credits Image by Gerd Altmann on Pixabay Gerd Altmann Pixabay This article is part of the Refactoring Series. How to Improve Your Code With Easy Refactorings How to Improve Your Code With Easy Refactorings

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