kindof understand mvvm

app/build.gradle

@@ -38,4 +38,23 @@ dependencies {
     testImplementation 'junit:junit:4.+'
     androidTestImplementation 'androidx.test.ext:junit:1.1.2'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
+    dependencies {
+        def room_version = "2.3.0"
+
+        implementation "androidx.room:room-runtime:$room_version"
+        annotationProcessor "androidx.room:room-compiler:$room_version"
+
+        // optional - RxJava2 support for Room
+        implementation "androidx.room:room-rxjava2:$room_version"
+
+        // optional - RxJava3 support for Room
+        implementation "androidx.room:room-rxjava3:$room_version"
+
+        // optional - Guava support for Room, including Optional and ListenableFuture
+        implementation "androidx.room:room-guava:$room_version"
+
+        // optional - Test helpers
+        testImplementation "androidx.room:room-testing:$room_version"
+    }
+
 }

app/src/main/java/com/example/wiimmterfaceandroid/MainActivity.java

@@ -3,14 +3,31 @@ package com.example.wiimmterfaceandroid;
 
 
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.fragment.app.FragmentContainerView;
+import androidx.room.Room;
 
 import android.os.Bundle;
 
+import com.example.wiimmterfaceandroid.database.AppDatabase;
+
 public class MainActivity extends AppCompatActivity {
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        FragmentContainerView fcInput = findViewById(R.id.recent_friend_codes_fragment);
+        AppDatabase database = Room.databaseBuilder(this, AppDatabase.class, "friend-codes-db").build();
+
         setContentView(R.layout.activity_main);
+        if (savedInstanceState == null) {
+            getSupportFragmentManager().beginTransaction()
+                    .replace(R.id.friend_code_input_fragment, WatchCodeFragment.class, null)
+                    .setReorderingAllowed(true)
+                    .commit();
+            getSupportFragmentManager().beginTransaction()
+                    .replace(R.id.recent_friend_codes_fragment, RecentCodesFragment.class, null)
+                    .setReorderingAllowed(true)
+                    .commit();
+        }
     }
 }

app/src/main/java/com/example/wiimmterfaceandroid/RecentCodesFragment.java

@@ -1,4 +1,9 @@
 package com.example.wiimmterfaceandroid;
 
-public class RecentCodesFragment {
+import androidx.fragment.app.Fragment;
+
+public class RecentCodesFragment extends Fragment {
+
+    public RecentCodesFragment() { super(R.layout.fragment_recent_friend_codes); }
+
 }

app/src/main/java/com/example/wiimmterfaceandroid/WatchCodeFragment.java

@@ -1,4 +1,19 @@
 package com.example.wiimmterfaceandroid;
 
-public class WatchCodeFragment {
+import android.os.Bundle;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+
+public class WatchCodeFragment extends Fragment {
+
+    public WatchCodeFragment() { super(R.layout.friend_code_input_fragment); }
+
+    @Override
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+
+    }
 }

app/src/main/java/com/example/wiimmterfaceandroid/database/AppDatabase.java

@@ -0,0 +1,11 @@
+package com.example.wiimmterfaceandroid.database;
+
+import androidx.room.Database;
+import androidx.room.RoomDatabase;
+
+import com.example.wiimmterfaceandroid.model.FriendCode;
+
+@Database(entities = {FriendCode.class}, version=1)
+public abstract class AppDatabase extends RoomDatabase {
+    public abstract FriendCodeDao getFriendCodeDao();
+}

app/src/main/java/com/example/wiimmterfaceandroid/database/FriendCodeDao.java

@@ -0,0 +1,30 @@
+package com.example.wiimmterfaceandroid.database;
+
+import androidx.room.Dao;
+import androidx.room.Delete;
+import androidx.room.Insert;
+import androidx.room.Query;
+import androidx.room.Update;
+
+import com.example.wiimmterfaceandroid.model.FriendCode;
+
+import java.util.List;
+
+@Dao
+public interface FriendCodeDao {
+
+    @Query("SELECT * FROM friendcode")
+    public List<FriendCode> getAll();
+
+    @Query("SELECT * FROM friendcode")
+    public FriendCode findByCode(String friendCode);
+
+    @Insert
+    public void insert(FriendCode friendCode);
+
+    @Update
+    public void update(FriendCode friendCode);
+
+    @Delete
+    public void delete(FriendCode friendCode);
+}

app/src/main/java/com/example/wiimmterfaceandroid/model/FriendCode.java

@@ -0,0 +1,13 @@
+package com.example.wiimmterfaceandroid.model;
+
+import androidx.room.ColumnInfo;
+import androidx.room.Entity;
+
+@Entity
+public class FriendCode {
+    @ColumnInfo(name="name")
+    public String name;
+
+    @ColumnInfo(name="friendCode")
+    public String friendCode;
+}

app/src/main/java/com/example/wiimmterfaceandroid/viewmodel/FriendCodeViewModel.java

@@ -0,0 +1,9 @@
+package com.example.wiimmterfaceandroid.viewmodel;
+
+import com.example.wiimmterfaceandroid.model.FriendCode;
+
+public class FriendCodeViewModel {
+    FriendCode friendCode = new FriendCode();
+
+
+}

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

@@ -7,16 +7,17 @@
     android:id="@+id/drawer_layout"
     tools:context=".MainActivity">
 
-    <androidx.coordinatorlayout.widget.CoordinatorLayout
+    <androidx.constraintlayout.widget.ConstraintLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:fitsSystemWindows="true">
 
         <com.google.android.material.appbar.AppBarLayout
-            style="@style/Widget.MaterialComponents.AppBarLayout.Primary"
+            android:id="@+id/appBarLayout"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:fitsSystemWindows="true">
+            android:fitsSystemWindows="true"
+            app:layout_constraintTop_toTopOf="parent">
 
             <com.google.android.material.appbar.MaterialToolbar
                 android:id="@+id/toolbar"
@@ -31,22 +32,22 @@
         </com.google.android.material.appbar.AppBarLayout>
 
         <androidx.fragment.app.FragmentContainerView
-            android:id="@+id/fragment_container2"
+            android:id="@+id/friend_code_input_fragment"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
+            app:layout_constraintTop_toBottomOf="@+id/appBarLayout" />
 
         <androidx.fragment.app.FragmentContainerView
-            android:id="@+id/fragment_container"
+            android:id="@+id/recent_friend_codes_fragment"
             android:layout_width="match_parent"
-            android:layout_height="match_parent"
+            android:layout_height="wrap_content"
-            app:layout_behavior="@string/appbar_scrolling_view_behavior"
+            android:hapticFeedbackEnabled="false"
-            />
+            app:layout_constraintTop_toBottomOf="@+id/friend_code_input_fragment" />
 
         <!-- Screen content -->
         <!-- Use app:layout_behavior="@string/appbar_scrolling_view_behavior" to fit below top app bar -->
 
-    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+    </androidx.constraintlayout.widget.ConstraintLayout>
 
 
 </androidx.drawerlayout.widget.DrawerLayout>

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

@@ -31,7 +31,7 @@
         </com.google.android.material.appbar.AppBarLayout>
 
         <androidx.fragment.app.FragmentContainerView
-            android:id="@+id/fragment_container"
+            android:id="@+id/recent_friend_codes_fragment"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             app:layout_behavior="@string/appbar_scrolling_view_behavior" />

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

@@ -22,7 +22,6 @@
         android:drawablePadding="15dp"
         android:ems="10"
         android:inputType="textPersonName"
-        android:text="Friend code"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/textView2" />