How to do it...

1. Edit the res/layout/activity_main.xml file so it includes a button as defined here:

<Button
    android:id="@+id/buttonLeft"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_centerVertical="true"
    android:onClick="onClickLeft"
    android:text="Left Button"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"/>

2. Now make a copy of activity_main.xml and call it activity_main2.xml. Change the button so it matches the following:

<Button
    android:id="@+id/buttonLeft"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_centerVertical="true"
    android:onClick="onClickRight"
    android:text="Right Button"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintHorizontal_bias="1.0"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"/>

3. Open MainActivity.java and add the following two methods to handle the button clicks:

public void onClickLeft(View view) { 
    setContentView(R.layout.activity_main2); 
} 
 
public void onClickRight(View view) { 
    setContentView(R.layout.activity_main); 
} 

4. Run this application on a device or emulator to see it in action.