Contract and implementation

Sample.kt

// Contract
interface INormalize{

    fun order()

    fun normalize()

    fun getScore()
}

// Base class
abstract class Normalize : INormalize{

    override fun order() {

    }

    override fun getScore() {

    }
}

// Implementation class
class AdNormalize : Normalize(){

    override fun normalize() {
        normalizeEntry()
    }

    private fun normalizeEntry(){
        System.out.print("entry")
    }
}

// Implementation class
class KeywordNormalize : Normalize(){

    override fun normalize() {
        normalizeBig()
    }

    private fun normalizeBig(){
        System.out.print("big")
    }
}


fun main(){

    val normalize : INormalize

    normalize = KeywordNormalize()

    normalize.normalize()
}