23.2 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

protected void onCreate(Bundle savedInstanceState) {

       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.javalayout;

 

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import androidx.constraintlayout.widget.ConstraintLayout;

...