refactor(database): use Jetpack's Navigation Component

database/app/build.gradle

@@ -35,6 +35,8 @@ dependencies {
     implementation 'androidx.appcompat:appcompat:1.2.0'
     implementation 'androidx.recyclerview:recyclerview:1.1.0'
     implementation 'com.google.android.material:material:1.2.1'
+    implementation 'androidx.navigation:navigation-fragment-ktx:2.3.2'
+    implementation 'androidx.navigation:navigation-ui-ktx:2.3.2'
 
     // Import the Firebase BoM (see: https://firebase.google.com/docs/android/learn-more#bom)
     implementation platform('com.google.firebase:firebase-bom:26.1.1')

database/app/src/main/AndroidManifest.xml

@@ -20,21 +20,12 @@
         <activity
             android:name=".java.MainActivity"
             android:label="@string/app_name"
-            android:theme="@style/AppTheme" />
+            android:theme="@style/AppTheme.NoActionBar" />
 
         <activity
             android:name=".kotlin.MainActivity"
             android:label="@string/app_name"
-            android:theme="@style/AppTheme" />
-
-        <activity android:name=".java.SignInActivity" />
-        <activity android:name=".kotlin.SignInActivity" />
-
-        <activity android:name=".java.NewPostActivity" />
-        <activity android:name=".kotlin.NewPostActivity" />
-
-        <activity android:name=".java.PostDetailActivity" />
-        <activity android:name=".kotlin.PostDetailActivity" />
+            android:theme="@style/AppTheme.NoActionBar" />
     </application>
 
 </manifest>

database/app/src/main/java/com/google/firebase/quickstart/database/EntryChoiceActivity.kt

@@ -11,11 +11,11 @@ class EntryChoiceActivity : BaseEntryChoiceActivity() {
                 Choice(
                         "Java",
                         "Run the Firebase Realtime Database quickstart written in Java.",
-                        Intent(this, com.google.firebase.quickstart.database.java.SignInActivity::class.java)),
+                        Intent(this, com.google.firebase.quickstart.database.java.MainActivity::class.java)),
                 Choice(
                         "Kotlin",
                         "Run the Firebase Realtime Database quickstart written in Kotlin.",
-                        Intent(this, com.google.firebase.quickstart.database.kotlin.SignInActivity::class.java))
+                        Intent(this, com.google.firebase.quickstart.database.kotlin.MainActivity::class.java))
         )
     }
 }

database/app/src/main/java/com/google/firebase/quickstart/database/java/BaseActivity.java → database/app/src/main/java/com/google/firebase/quickstart/database/java/BaseFragment.java

@@ -3,17 +3,15 @@
 import android.view.View;
 import android.widget.ProgressBar;
 
-import androidx.appcompat.app.AppCompatActivity;
+import androidx.fragment.app.Fragment;
 
 import com.google.firebase.auth.FirebaseAuth;
 
-
-public class BaseActivity extends AppCompatActivity {
-
+public class BaseFragment extends Fragment {
     private ProgressBar mProgressBar;
 
     public void setProgressBar(int resId) {
-        mProgressBar = findViewById(resId);
+        mProgressBar = getView().findViewById(resId);
     }
 
     public void showProgressBar() {
@@ -31,6 +29,4 @@ public void hideProgressBar() {
     public String getUid() {
         return FirebaseAuth.getInstance().getCurrentUser().getUid();
     }
-
-
 }

database/app/src/main/java/com/google/firebase/quickstart/database/java/MainActivity.java

@@ -16,91 +16,51 @@
 
 package com.google.firebase.quickstart.database.java;
 
-import android.content.Intent;
 import android.os.Bundle;
-import android.view.Menu;
-import android.view.MenuItem;
 import android.view.View;
 
-import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentPagerAdapter;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.navigation.NavController;
+import androidx.navigation.NavDestination;
+import androidx.navigation.Navigation;
 
-import com.google.firebase.auth.FirebaseAuth;
+import com.google.android.material.floatingactionbutton.FloatingActionButton;
 import com.google.firebase.quickstart.database.R;
 import com.google.firebase.quickstart.database.databinding.ActivityMainBinding;
-import com.google.firebase.quickstart.database.java.fragment.MyPostsFragment;
-import com.google.firebase.quickstart.database.java.fragment.MyTopPostsFragment;
-import com.google.firebase.quickstart.database.java.fragment.RecentPostsFragment;
 
-public class  MainActivity extends BaseActivity {
+public class  MainActivity extends AppCompatActivity {
 
-    private static final String TAG = "MainActivity";
+    private FloatingActionButton fab;
+    private NavController navController;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         ActivityMainBinding binding = ActivityMainBinding.inflate(getLayoutInflater());
         setContentView(binding.getRoot());
+        setSupportActionBar(binding.toolbar);
 
-        // Create the adapter that will return a fragment for each section
-        FragmentPagerAdapter mPagerAdapter = new FragmentPagerAdapter(getSupportFragmentManager(),
-                FragmentPagerAdapter.BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT) {
-            private final Fragment[] mFragments = new Fragment[]{
-                    new RecentPostsFragment(),
-                    new MyPostsFragment(),
-                    new MyTopPostsFragment(),
-            };
-            private final String[] mFragmentNames = new String[]{
-                    getString(R.string.heading_recent),
-                    getString(R.string.heading_my_posts),
-                    getString(R.string.heading_my_top_posts)
-            };
+        fab = binding.fab;
 
+        navController = Navigation.findNavController(this, R.id.nav_host_fragment);
+        navController.setGraph(R.navigation.nav_graph_java);
+        navController.addOnDestinationChangedListener(new NavController.OnDestinationChangedListener() {
             @Override
-            public Fragment getItem(int position) {
-                return mFragments[position];
-            }
-
-            @Override
-            public int getCount() {
-                return mFragments.length;
-            }
-
-            @Override
-            public CharSequence getPageTitle(int position) {
-                return mFragmentNames[position];
-            }
-        };
-        // Set up the ViewPager with the sections adapter.
-        binding.container.setAdapter(mPagerAdapter);
-        binding.tabs.setupWithViewPager(binding.container);
-
-        // Button launches NewPostActivity
-        binding.fabNewPost.setOnClickListener(new View.OnClickListener() {
-            @Override
-            public void onClick(View v) {
-                startActivity(new Intent(MainActivity.this, NewPostActivity.class));
+            public void onDestinationChanged(@NonNull NavController controller, @NonNull NavDestination destination, @Nullable Bundle arguments) {
+                if (destination.getId() == R.id.MainFragment) {
+                    fab.setVisibility(View.VISIBLE);
+                    fab.setOnClickListener(new View.OnClickListener() {
+                        @Override
+                        public void onClick(View view) {
+                            navController.navigate(R.id.action_MainFragment_to_NewPostFragment);
+                        }
+                    });
+                } else {
+                    fab.setVisibility(View.GONE);
+                }
             }
         });
     }
-
-    @Override
-    public boolean onCreateOptionsMenu(Menu menu) {
-        getMenuInflater().inflate(R.menu.menu_main, menu);
-        return true;
-    }
-
-    @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
-        int i = item.getItemId();
-        if (i == R.id.action_logout) {
-            FirebaseAuth.getInstance().signOut();
-            startActivity(new Intent(this, SignInActivity.class));
-            finish();
-            return true;
-        } else {
-            return super.onOptionsItemSelected(item);
-        }
-    }
-
 }