Android Development with Kotlin

Read-write versus read-only

All the properties in the previous examples were defined as read-write (a setter and a getter are generated). To define read-only properties, we need to use the val keyword, so only a getter will be generated. Let's look at a simple example:

    class Person( 
        var name: String,         // Read-write property (generated getter and setter)        val age: Int      // Read-only property (generated getter) 
    ) 
    //usage 
    val person = Person("Eva", 25) 
 
    val name = person.name 
    person.name = "Kate" 
 
    val age = person.age 
    person.age = 28 //error: read-only property 

Kotlin does not support write-only properties (properties of which only setter is generated).

Keyword	Read	Write
var	Yes	Yes
val	Yes	No
(unsupported)	No