Lesson 6 - Mastering Kotlin's Conditional Statements: When, If-Else, and Ranges

Lesson No 6 Variables in Kotlin Programming

Step 1: Understanding the "When" Expression

In Kotlin, the "when" expression is a powerful tool that allows you to perform complex conditional logic in a concise and readable manner. Unlike the traditional if-else statements, the "when" expression provides a more intuitive and organized way to handle multiple conditions.

The syntax for the "when" expression is as follows:

when (variable) {

condition1 -> action1

condition2 -> action2

...

else -> defaultAction

}

In this structure, the "when" keyword is followed by a variable or expression that will be evaluated against the provided conditions. Each condition is separated by an arrow (->) and is followed by the corresponding action to be taken if that condition is met. The "else" block is optional and can be used to specify a default action if none of the conditions are satisfied.

Step 2: Exploring the Advantages of "When"

The "when" expression offers several advantages over traditional if-else statements:

1. Conciseness: The "when" expression allows you to condense multiple if-else statements into a single, more readable block of code.
2. Readability: The clear and organized structure of the "when" expression makes it easier to understand and maintain your code.
3. Flexibility: The "when" expression can handle a wide range of data types, including integers, strings, and even custom objects.
4. Exhaustiveness: The "when" expression can be configured to ensure that all possible cases are handled, reducing the risk of unintended behavior.

Step 3: Combining "When" with Ranges

Another powerful feature in Kotlin is the use of ranges, which can be seamlessly integrated with the "when" expression. Ranges allow you to define a continuous set of values, making it easier to handle a wide range of conditions.

The syntax for using ranges with the "when" expression is as follows:

when (variable) {

in range1 -> action1

in range2 -> action2

...

else -> defaultAction

}

In this case, the "in" keyword is used to check if the variable falls within the specified range. This approach can be particularly useful when dealing with numerical values, such as ages or dates.

Step 4: Comparing "When" and If-Else

While both the "when" expression and if-else statements can be used to handle conditional logic, there are some key differences between the two:

• Readability: The "when" expression generally provides a more organized and readable structure, especially when dealing with multiple conditions.
• Exhaustiveness: The "when" expression can be configured to ensure that all possible cases are handled, reducing the risk of unintended behavior.
• Flexibility: The "when" expression can handle a wider range of data types, including custom objects, making it more versatile than traditional if-else statements.
• Performance: In some cases, the "when" expression may be more efficient than a series of if-else statements, as the compiler can optimize the code more effectively.

Ultimately, the choice between using "when" or if-else statements depends on the specific requirements of your project and the complexity of the conditional logic you need to handle.

Step 5: Putting It All Together

Now that you have a solid understanding of the "when" expression, let's put it into practice with a real-world example. Imagine you're building an application that needs to determine a person's voting eligibility based on their age.

Using the "when" expression and ranges, you can create a concise and readable code snippet to handle this scenario:

when (personAge) {

in 1..17 -> println("Not eligible to vote")

in 18..49 -> println("Eligible to vote")

in 50..100 -> println("Eligible to vote with senior discount")

else -> println("Invalid age")

}

In this example, the "when" expression checks the "personAge" variable against three different ranges: 1-17, 18-49, and 50-100. Depending on which range the person's age falls into, the corresponding action is executed, such as printing a message about their voting eligibility.

By using the "when" expression and ranges, you've created a concise and easily maintainable solution that can handle a wide range of age values, making it more flexible and readable than a series of if-else statements.

Conclusion

In this blog post, we've explored the power of Kotlin's "when" expression and its integration with ranges. We've discussed the advantages of using "when" over traditional if-else statements, including improved readability, flexibility, and exhaustiveness.

By mastering the "when" expression and ranges, you can write more concise, organized, and maintainable Kotlin code, making you a more efficient and effective Kotlin developer. Remember to practice and experiment with these concepts to fully internalize their benefits and find the best use cases for your projects.