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Learn how to effectively use custom setters in Kotlin to manipulate a property value upon initialization.
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This video is based on the question https://stackoverflow.com/q/66102079/ asked by the user 'Brice Harismendy' ( https://stackoverflow.com/u/8919169/ ) and on the answer https://stackoverflow.com/a/66103820/ provided by the user 'Madhu Bhat' ( https://stackoverflow.com/u/9840318/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use a Custom Setter in Kotlin for Class Properties

Kotlin offers powerful features for property declarations, one of the most useful being custom setters. However, many new Kotlin developers find it confusing to effectively implement these custom setters, especially during the initialization of class properties. In this guide, we'll explore the question, "How to specify a particular setter for a property of a class?" and provide a clear solution to ensure your setter works as intended.

The Problem: Unexpected Output

Imagine you’re working on a Kotlin project and following a course that talks about custom setters for class properties. You write the following class code:

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Upon running this code, you’re eager to see the output, which should display "my awesome stuff". Instead, you see "stuff" printed. This can be perplexing, but the explanation is more straightforward than it seems.

Understanding the Setter Behavior

When you initialize your Course object using:

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The custom setter for title does not get triggered. Consequently, the default value remains unchanged, leading to the output of "stuff". This occurs because the setter is only invoked when you explicitly set a value to title after the object creation, as shown here:

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Making the Setter Work on Initialization

To have the setter function as intended during the object initialization, you can utilize an init block. Here’s how you can modify your class definition:

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Alternative Approach: Setting Directly in the init Block

If you prefer simplicity and want to avoid custom setters altogether, you can set the title property directly in the init block. Here’s how that would look:

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Conclusion

Using custom setters in Kotlin can seem daunting at first, but with a proper understanding of how property initialization works, you can easily manipulate data in your classes. Whether you choose to use a custom setter or set the property value directly in the init block, both approaches allow you to achieve the desired outcome of modifying the title property effectively.

By employing these methods, you can enhance the functionality of your classes and ensure your application behaves as expected. So go ahead, give custom setters a try and see what other enhancements you can implement in your Kotlin applications!