Calling the arrow and allowing back function to return to the parent activity which is the mainActivity (first screen)

app/src/main/AndroidManifest.xml

@@ -9,7 +9,11 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.MyWeather">
-        <activity android:name=".AddCity"></activity>
+        <!-- Adding an attribute to remove the app bar only in the activity that allows the user to add a city-->
+        <activity android:name=".AddCity"
+            android:parentActivityName=".MainActivity"
+            android:theme="@style/Theme.MyWeather.NoActionBar">
+        </activity>
         <activity android:name=".MainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

app/src/main/java/fr/romanet/vj/apps/myweather/AddCity.java

@@ -1,14 +1,20 @@
 package fr.romanet.vj.apps.myweather;
 
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
 
 import android.os.Bundle;
 
 public class AddCity extends AppCompatActivity {
 
     @Override
-    protected void onCreate(Bundle savedInstanceState) {
+    protected void onCreate(Bundle savedInstanceState)
+    {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.add_city_page);
+        Toolbar toolbarAddCity = (Toolbar) findViewById(R.id.toolbarAddCity);
+        setSupportActionBar(toolbarAddCity);
+        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+        getSupportActionBar().setDisplayShowHomeEnabled(true);
     }
 }

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

@@ -13,18 +13,20 @@
         android:theme="@style/Theme.MyWeather.AppBarOverlay">
 
         <androidx.appcompat.widget.Toolbar
-            android:id="@+id/toolbar"
+            android:id="@+id/toolbarAddCity"
             android:layout_width="match_parent"
-            android:layout_height="75dp"
+            android:layout_height="60dp"
             android:background="?attr/colorPrimary"
             app:title="Add a city"
+            android:minHeight="60dp"
             app:popupTheme="@style/Theme.MyWeather.PopupOverlay" />
 
+        
     </com.google.android.material.appbar.AppBarLayout>
 
     <Space
         android:layout_width="match_parent"
-        android:layout_height="130dp" />
+        android:layout_height="120dp" />
 
     <TextView
         android:id="@+id/textView"
@@ -40,7 +42,7 @@
 
     <Space
         android:layout_width="match_parent"
-        android:layout_height="120dp" />
+        android:layout_height="100dp" />
 
     <EditText
         android:id="@+id/editText"
@@ -53,7 +55,7 @@
 
     <Space
         android:layout_width="match_parent"
-        android:layout_height="100dp" />
+        android:layout_height="90dp" />
 
     <Button
         android:id="@+id/btnSave"

app/src/main/res/values/themes.xml

@@ -1,14 +1,17 @@
 <resources xmlns:tools="http://schemas.android.com/tools">
     <!-- Base application theme. -->
     <style name="Theme.MyWeather" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+
         <!-- Primary brand color. -->
         <item name="colorPrimary">@color/red</item>
         <item name="colorPrimaryVariant">@color/red</item>
         <item name="colorOnPrimary">@color/white</item>
+
         <!-- Secondary brand color. -->
         <item name="colorSecondary">@color/red</item>
         <item name="colorSecondaryVariant">@color/red</item>
         <item name="colorOnSecondary">@color/white</item>
+
         <!-- Status bar color. -->
         <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
         <!-- Customize your theme here. -->