I am trying to change the background color of theRelativeLayout variable named mealLayout

import android.app.Activity
import android.os.Bundle
import android.widget.TextView
import android.widget.RelativeLayout
import android.graphics.Color
import android.support.v7.app.AppCompatActivity
import android.widget.Button
import java.util.*

class MealActivity : Activity() {
  var mealLayout: RelativeLayout? = null

  override fun onCreate(savedInstanceState: Bundle) {
    mealLayout.!!setBackgroundColor(Color.GREEN)
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_meal)

    val foodLabel = findViewById(R.id.foodTextView) as TextView
    val drinkLabel = findViewById(R.id.drinkTextView) as TextView
    val mealLayout = findViewById(R.id.mealLayout) as RelativeLayout
    mealLayout!!.setBackgroundColor(Color.GREEN)
  }
}