ExpandViewActivity.kt

package com.android.animationproject.view

import android.animation.AnimatorSet
import android.os.Bundle
import android.view.View
import android.view.ViewTreeObserver.OnGlobalLayoutListener
import androidx.appcompat.app.AppCompatActivity
import androidx.cardview.widget.CardView
import androidx.constraintlayout.widget.ConstraintLayout
import androidx.core.content.ContextCompat
import com.android.animationproject.R
import com.android.animationproject.utils.AnimatorUtils

class ExpandViewActivity : AppCompatActivity() {

    private lateinit var cardBox: CardView
    private lateinit var intro: ConstraintLayout
    private lateinit var detail: ConstraintLayout
    private var shouldExpand = true

    private var oldHeight = 0
    private var newHeight= 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_expand_view)

        cardBox = findViewById(R.id.card_container)
        intro = findViewById(R.id.intro)
        detail = findViewById(R.id.detail)

        setViewHeight()

        cardBox.setOnClickListener {
            if(shouldExpand) {
                expandAnimation()
                shouldExpand = shouldExpand.not()
            } else {
                collapseAnimation()
                shouldExpand =  shouldExpand.not()
            }
        }
    }
    private fun setViewHeight() {...} 
    private fun expandAnimation() {...}
    private fun collapseAnimation() {...)    
}