Why Kotlin Data class are best for your model?

In this post we will discuss key differences between data class and normal class in Kotlin.

Summary of kotlin data classes

1. Data classes are data holders. Used for POJO or Model classes.
2. Two data class objects are easily compared using == operator.
3. Data classes are easy to log with default toString() method.
4. They require at least one val or var parameter in primary constructor.
5. data keyword is required before class during definition.
6. default hashCode() & toString() methods readily available.

Lets try to understand this further with some code:

Normal class

class Normal(
val name: String,
val age: Int)

Data class

data class Data(
val name:String,
val age:Int)

Now we can initialise these classes.

val dataObject = Data("kotlin",1)
val normalObject = Normal("Java",2)

toString() comparision

println("Data object to string is $dataObject")
println("Normal object to string is $normalObject")

Output

Data object to string is Data(name=kotlin, age=1)
Normal object to string is Normal@12edcd21

Object comparision

val similarDataObject = Data("kotlin",1)
val similarNormalObject = Normal("Java",2)

println("Compare 2 data classes ${dataObject==similarDataObject}")
println("Compare 2 normal classes ${normalObject==similarNormalObject}")

Output

Compare 2 data classes true
Compare 2 normal classes false

componentN method

The componentN method gives you variable at Nth position in the order of definition in your data class.

println("Component1: ${dataObject.component1()} & Component2: ${dataObject.component2()}")

Output

Component1: kotlin & Component2: 1

Thank you! Happy Learning!!