Kotlin Code Pills —OOP-Properties 1

Kotlin is an Object-Oriented language and in this article, we will look into the basics of Properties in Kotlin.

property = field + accessors

Here let’s look properties in Java

public class JavaClass {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

In Java, to get or set the data from properties we need to define getter and setter methods, but in Kotlin getter and setter methods generated automatically when you define a property like below

class KotlinClass(
        var name: String
)

In Kotlin you can create two types of properties

• val: Read-Only Property
• var: Mutable Property

With more in details;

val= field + getter

var= field + getter + setter

In Kotlin example above, to get and set name the property like below;

kotlinClass.name             // getter
kotlinClass.name = "John"    //setter

Property without field

In Kotlin you can also create property without field like below by using get and set functions

class Rectangle(val height: Int, val width: Int) {
    val isSquare: Boolean
        get() {
            return height == width
        }
}

and you can use like that

val rectangle = Rectangle(1,3)
println(rectangle.isSquare)    //false

Default Accessors

In Kotlin you can also set some default value in Properties.

class KotlinClass(
        var name: String = "John"
)

In this code pills, we see how we define properties in Kotlin and read-only & mutable properties. In the next code pills, we will go thought some more details in Properties. See you in the next Kotlin Code pills.