Removed DisplayMessageActivity and added MainActivity

app/src/main/AndroidManifest.xml

@@ -9,21 +9,21 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
-        <activity android:name=".DisplayMessageActivity"
-            android:parentActivityName=".MessageListActivity">
-            <!-- The meta-data tag is required if you support API level 15 and lower -->
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value=".MessageListActivity" />
-        </activity>
-
-        <activity android:name=".MessageListActivity">
+        <activity android:name=".MainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <activity
+            android:name=".MessageListActivity"
+            android:parentActivityName=".MainActivity">
+            <!-- The meta-data tag is required if you support API level 15 and lower -->
+            <meta-data
+                android:name="android.support.PARENT_ACTIVITY"
+                android:value=".MainActivity" />
+        </activity>
     </application>
 
 </manifest>

app/src/main/java/com/example/myfirstapp/MainActivity.kt

@@ -0,0 +1,12 @@
+package com.example.myfirstapp
+
+import androidx.appcompat.app.AppCompatActivity
+import android.os.Bundle
+
+class MainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+    }
+}

app/src/main/res/layout/activity_display_message.xml

@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context=".DisplayMessageActivity">
-
-    <TextView
-        android:id="@+id/textView"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginTop="16dp"
-        android:text="TextView"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
-</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_main.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".MainActivity">
+
+</androidx.constraintlayout.widget.ConstraintLayout>