‘Keep Me’ Note App – Usign Kotlin and Jetpack Compose with Firebase and Admob Ads

Introduction

Welcome to the "Keep Me" Note App tutorial! In this tutorial, we will be building a note-taking app using Kotlin, Jetpack Compose, Firebase, and AdMob Ads. This app will allow users to create, edit, and delete notes, as well as view them in a list. We will also be integrating AdMob Ads to generate revenue from the app.

Requirements

• Android Studio 4.0 or later
• Kotlin 1.6.0 or later
• Jetpack Compose 1.0.0 or later
• Firebase SDK for Android
• AdMob SDK for Android

Step 1: Set up the project

• Create a new Android project in Android Studio.
• Choose "Empty Activity" as the template.
• Name the project "KeepMe".
• Set the package name to "com.example.keepme".
• Leave the rest of the settings as default.

Step 2: Add dependencies

• In the build.gradle file, add the following dependencies:

  dependencies {
  implementation 'androidx.compose.ui:ui-tooling:1.0.0'
  implementation 'androidx.compose.material:material:1.0.0'
  implementation 'com.google.firebase:firebase-firestore:24.1.0'
  implementation 'com.google.firebase:firebase-auth:21.0.3'
  implementation 'com.google.android.gms:play-services-ads:21.2.0'
  }

• Sync the project with Gradle Files.

Step 3: Set up Firebase

• Create a new Firebase project in the Firebase console.
• Create a new Firestore database.
• Create a new Authentication system using Email/Password.
• Go to the "Add Firebase to your Android app" page and follow the instructions to add the Firebase SDK to your project.
• Add the following lines to the build.gradle file:

  firebase {
  sdk {
      googleServices {
          releaseMode()
      }
  }
  }

• Sync the project with Gradle Files.

Step 4: Set up AdMob

• Create a new AdMob app in the AdMob console.
• Go to the "Add AdMob to your Android app" page and follow the instructions to add the AdMob SDK to your project.
• Add the following lines to the build.gradle file:

  implementation 'com.google.android.gms:play-services-ads:21.2.0'

• Sync the project with Gradle Files.

Step 5: Create the Note App

• Create a new Java class called Note:

  data class Note(val id: String, val title: String, val text: String)

• Create a new ViewModel class called NoteViewModel:

  class NoteViewModel(private val noteDao: NoteDao) : ViewModel() {
  private val _notes = MutableLiveData<List<Note>>()
  val notes: LiveData<List<Note>> = _notes
  
  fun getNotes() {
      _notes.value = noteDao.getNotes()
  }
  
  fun addNote(note: Note) {
      noteDao.addNote(note)
  }
  
  fun deleteNote(note: Note) {
      noteDao.deleteNote(note)
  }
  }

• Create a new Jetpack Compose file called NoteList.kt:

  
  @Composable
  fun NoteList(notes: List<Note>, viewModel: NoteViewModel) {
  LazyColumn {
      items(notes) { note ->
          NoteItem(note, viewModel)
      }
  }
  }

@Composable fun NoteItem(note: Note, viewModel: NoteViewModel) { Card(elevation = 4.dp) { Column { Text(text = note.title, style = MaterialTheme.typography.titleLarge) Text(text = note.text, style = MaterialTheme.typography.body1) Row { TextButton(onClick = { viewModel.deleteNote(note) }) { Text(text = "Delete") } } } } }

* Create a new Jetpack Compose file called `NoteEditor.kt`:
```kotlin
@Composable
fun NoteEditor(viewModel: NoteViewModel) {
    Column {
        TextEditor(
            value = viewModel.notes.value?.firstOrNull()?.text?: "",
            onValueChange = { newText ->
                viewModel.notes.value = (viewModel.notes.value?.toList()?: emptyList()).apply {
                    firstOrNull { it.text == newText }?.text = newText
                }
            }
        )
        TextButton(onClick = { viewModel.addNote(Note("new", "", "")) }) {
            Text(text = "Save")
        }
    }
}

• Create a new activity called MainActivity.kt:

  class MainActivity : AppCompatActivity() {
  private lateinit var viewModel: NoteViewModel
  private lateinit var notes: List<Note>
  
  override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContent {
          NoteApp(viewModel = viewModel, notes = notes)
      }
  }
  }

• Create a new Jetpack Compose file called NoteApp.kt:

  @Composable
  fun NoteApp(viewModel: NoteViewModel, notes: List<Note>) {
  Column {
      NoteList(notes = notes, viewModel = viewModel)
      NoteEditor(viewModel = viewModel)
  }
  }

  Step 6: Add AdMob Ads

• Create a new Java class called AdManager:

  public class AdManager {
  private static final String ADMOB_APP_ID = "YOUR_ADMOB_APP_ID";
  private AdView adView;
  
  public AdManager(Context context) {
      adView = new AdView(context);
      adView.setAdSize(AdSize.BANNER);
      adView.setAdUnitId(ADMOB_APP_ID);
      adView.loadAd(new AdRequest.Builder().build());
  }
  
  public AdView getAdView() {
      return adView;
  }
  }

• Add the AdManager to the MainActivity:

  class MainActivity : AppCompatActivity() {
  private lateinit var adManager: AdManager
  private lateinit var viewModel: NoteViewModel
  private lateinit var notes: List<Note>
  
  override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      adManager = AdManager(this)
      viewModel = NoteViewModel(NoteDao(this))
      notes = viewModel.getNotes()
      setContent {
          NoteApp(viewModel = viewModel, notes = notes)
      }
  }
  }

• Add the AdView to the NoteApp Composable:

  @Composable
  fun NoteApp(viewModel: NoteViewModel, notes: List<Note>) {
  Column {
      NoteList(notes = notes, viewModel = viewModel)
      NoteEditor(viewModel = viewModel)
      AdView(adManager.getAdView())
  }
  }

  Step 7: Run the app

• Run the app on an Android emulator or a physical device.
• The app will load the notes from the Firestore database and display them in a list.
• You can add new notes, edit existing notes, and delete notes.
• AdMob ads will be displayed at the bottom of the screen.

This is the end of the tutorial. You should now have a working note-taking app with Firebase authentication, Firestore database, and AdMob ads.