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How to Validate Class String Property Is Not Empty In Kotlin?

2 minutes read

To validate that a class string property is not empty in Kotlin, you can use the isNotEmpty() function along with the if statement.


Here's an example code snippet to demonstrate this:

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class MyClass {
    var name: String = ""

    fun validateName() {
        if (name.isNotEmpty()) {
            println("Name is not empty")
        } else {
            println("Name is empty")
        }
    }
}

fun main() {
    val myClass = MyClass()
    myClass.name = "John Doe"
    myClass.validateName() // Output: Name is not empty

    myClass.name = ""
    myClass.validateName() // Output: Name is empty
}


In this example, we have a class called MyClass with a string property name. The validateName() function checks if the name property is not empty using the isNotEmpty() function.


How do I validate that a string property is not null in kotlin?

In Kotlin, you can check if a string property is not null using the safe call operator ?. and the isNullOrEmpty() function. Here's an example:

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val myString: String? = "Hello, World!"

if (myString?.isNullOrEmpty() == false) {
    // String is not null or empty
    println("String is not null")
} else {
    // String is null or empty
    println("String is null or empty")
}


In this example, the myString?.isNullOrEmpty() expression checks if the myString property is not null and not empty. If it is not null and not empty, the condition == false is true, and the code inside the if block will be executed. Otherwise, the code inside the else block will be executed.


What is the kotlin function for checking if a string is empty?

In Kotlin, you can use the isEmpty() function to check if a string is empty.


Here's an example of how you can use it:

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val str = ""
if (str.isEmpty()) {
    println("The string is empty")
} else {
    println("The string is not empty")
}


This will output "The string is empty" as the string str is empty.


How to implement a validation function for a non-empty string property in kotlin?

You can implement a validation function for a non-empty string property in Kotlin by using a custom setter that checks if the string value is not empty before setting it. Here is an example implementation:

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class MyClass {
    var myString: String = ""
        set(value) {
            if (value.isNotEmpty()) {
                field = value
            } else {
                throw IllegalArgumentException("String cannot be empty")
            }
        }
}


In this example, the myString property has a custom setter that checks if the incoming value is not empty using the isNotEmpty() function. If the value is not empty, it sets the field (the backing field for the property) to the new value. If the value is empty, it throws an IllegalArgumentException.


You can then use this class and property as follows:

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fun main() {
    val obj = MyClass()
    obj.myString = "Hello, World!"
    println(obj.myString) // Output: Hello, World!
    
    try {
        obj.myString = ""
    } catch (e: IllegalArgumentException) {
        println(e.message) // Output: String cannot be empty
    }
}


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