31.2 Adding Views to an Activity

The onCreate() method is currently designed to use a resource layout file for the user interface. Begin, therefore, by deleting this line from the method:

override fun onCreate(savedInstanceState: Bundle?) {

    super.onCreate(savedInstanceState)

    setContentView(R.layout.activity_main)

}

The next modification is to add a ConstraintLayout object with a single Button view child to the activity. This involves the creation of new instances of the ConstraintLayout and Button classes. The Button view then needs to be added as a child to the ConstraintLayout view which, in turn, is displayed via a call to the setContentView() method of the activity instance:

package com.ebookfrenzy.kotlinlayout

 

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle

import androidx.constraintlayout.widget.ConstraintLayout

import android.widget.Button

import android.widget...