Kotlin Setters and Getters

In Kotlin, a getter is a method automatically generated to retrieve the value of a property, while a setter is a method generated to modify the value of a mutable property. Custom logic can be added to getters and setters if needed.

Getters:

Automatic Getter:

When you declare a property using var or val, Kotlin automatically generates a default getter. For val (read-only) properties, only the getter is generated

class Example {
    val readOnlyProperty: Int = 42  // Automatic getter is generated
}

To access the property:

val value = example.readOnlyProperty  // Accessing the property using the default getter

Custom Getter: A custom getter is a way to define how a property’s value should be calculated or retrieved when it is accessed. custom getter can be defined by using the get() method within the property declaration.

class Person(val firstName: String, val lastName: String) {
    // Custom getter for the fullName property
    val fullName: String
        get() {
            return "$firstName $lastName"
        }
}

fun main() {
    val person = Person("John", "Doe")
    println("Full Name: ${person.fullName}") // Full Name: John Doe
}

In this Example, When access the fullName get() will run and returns the fullname

Setters:

Automatic Setter:

For mutable properties declared with var, Kotlin generates both a getter and a setter. for val keyword kotlin only generated getters

class Example {
    var mutableProperty: Int = 42  // Automatic getter and setter are generated
}

To set the property:

example.mutableProperty = 54  // Setting the property using the default setter

Custom Setter: It is used to add custom logic that is executed when a property is assigned a new value. A custom setter is declared using the set() method within the property declaration. Here’s a simple example:

class Example {
    var customProperty: Int = 42
        set(value) {
            field = value * 2
        }
}

fun main() {
    var e1 = Example()
    println(e1.customProperty) // Output: 42

    
    //Setting the property using the custom setter
    e1.customProperty = 78    // Corrected line
    println(e1.customProperty) // Output: 156
}

In this example the customProperty has a custom setter that doubles the value assigned to it.