Potential solution

To implement Google sign-in functionality in your Android application, you need to make changes to both the front end and back end of your app. This involves updating the layout to include a Google sign-in button, configuring the necessary dependencies and permissions, and implementing the sign-in logic in your main activity. The goal is to allow users to sign in using their Google accounts, which enhances user experience by providing a quick and secure authentication method.

How to implement

Update the Layout File (activity_main.xml):

Add a Google Sign-In button to your layout. This button is provided by the Google Play services library and is specifically designed for Google sign-in.

<com.google.android.gms.common.SignInButton
   android:id="@+id/googleSignInButton"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_centerInParent="true" />

Modify the Build Configuration (build.gradle.kts):
- Add the Google Play services dependency for authentication to your build.gradle.kts file to enable Google sign-in features.
```
dependencies {
   implementation("com.google.android.gms:play-services-auth:20.4.1")
}
```
- Sync your project with Gradle files to download the necessary libraries.

Update the Android Manifest (AndroidManifest.xml):

Add internet permission to allow your app to communicate with Google's servers.

<uses-permission android:name="android.permission.INTERNET" />

Include metadata for Google services configuration, such as your Google API key.

<meta-data
   android:name="com.google.android.gms.version"
   android:value="@integer/google_play_services_version" />
<meta-data
   android:name="com.google.android.geo.API_KEY"
   android:value="YOUR_API_KEY_HERE" />

Replace "YOUR_API_KEY_HERE" with your actual Google API key.

Implement Sign-In Logic in MainActivity.kt:

Initialize the GoogleSignInClient with the appropriate options in the onCreate method.
Set up an onClickListener for the Google sign-in button to trigger the sign-in intent.
Handle the sign-in result in the onActivityResult method.

import android.content.Intent
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import com.google.android.gms.auth.api.signin.GoogleSignInOptions
import com.google.android.gms.common.api.ApiException

class MainActivity : AppCompatActivity() {

   private lateinit var googleSignInClient: GoogleSignInClient

   override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main)

       val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
           .requestEmail()
           .build()

       googleSignInClient = GoogleSignIn.getClient(this, gso)

       val googleSignInButton = findViewById<SignInButton>(R.id.googleSignInButton)
       googleSignInButton.setOnClickListener {
           signIn()
       }
   }

   private fun signIn() {
       val signInIntent = googleSignInClient.signInIntent
       startActivityForResult(signInIntent, RC_SIGN_IN)
   }

   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
       super.onActivityResult(requestCode, resultCode, data)

       if (requestCode == RC_SIGN_IN) {
           val task = GoogleSignIn.getSignedInAccountFromIntent(data)
           try {
               val account = task.getResult(ApiException::class.java)
               updateUI(account)
           } catch (e: ApiException) {
               updateUI(null)
           }
       }
   }

   private fun updateUI(account: GoogleSignInAccount?) {
       if (account != null) {
           // User is signed in
       } else {
           // User is not signed in
       }
   }

   companion object {
       private const val RC_SIGN_IN = 9001
   }
}

By following these steps, you will have successfully implemented Google sign-in functionality in your Android application, allowing users to authenticate using their Google accounts.

Click here to create a Pull Request with the proposed solution

Files used for this task:

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

To add a Google sign-in button to the layout and set its `onClickListener` to trigger the sign-in process, you can follow these steps: 1. **Add the Google Sign-In Button to the Layout:** You need to add a `SignInButton` to your XML layout file. This button is provided by the Google Play services library and is specifically designed for Google sign-in. Here is how you can add it to your `activity_main.xml`: ```xml ``` You can adjust the layout parameters such as `layout_width`, `layout_height`, and positioning attributes to fit your design needs. 2. **Set the `onClickListener` in Your Activity:** In your `MainActivity.kt`, you will need to find the button by its ID and set an `onClickListener` to initiate the Google sign-in process. This will be handled in the Java/Kotlin code, not in the XML file. Here's a basic example of how you might set this up in your activity: ```kotlin val googleSignInButton = findViewById(R.id.googleSignInButton) googleSignInButton.setOnClickListener { // Trigger the Google sign-in process signInWithGoogle() } ``` The `signInWithGoogle()` function should be implemented to handle the sign-in logic, which includes initializing the `GoogleSignInClient` and starting the sign-in intent. By following these steps, you will have added a Google sign-in button to your layout and set it up to trigger the sign-in process when clicked.

Changes on app/build.gradle.kts

To implement Google sign-in functionality, you need to add the necessary dependencies for Google Play services and authentication libraries in the `app/build.gradle.kts` file. Here's how you can modify the file: 1. **Add Google Play Services Dependency**: Include the Google Play services library for authentication. This is necessary to use Google sign-in features. 2. **Sync the Project**: After adding the dependencies, make sure to sync your project with Gradle files to download the necessary libraries. Here's the updated `app/build.gradle.kts` file with the required changes: ```kotlin plugins { alias(libs.plugins.android.application) alias(libs.plugins.jetbrains.kotlin.android) } android { namespace = "afrion.scientificcalculator" compileSdk = 34 defaultConfig { applicationId = "afrion.scientificcalculator" minSdk = 24 targetSdk = 34 versionCode = 1 versionName = "1.0" testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner" } buildTypes { release { isMinifyEnabled = false proguardFiles( getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro" ) } } compileOptions { sourceCompatibility = JavaVersion.VERSION_1_8 targetCompatibility = JavaVersion.VERSION_1_8 } kotlinOptions { jvmTarget = "1.8" } } dependencies { implementation(libs.androidx.core.ktx) implementation(libs.androidx.appcompat) implementation(libs.material) implementation(libs.androidx.activity) implementation(libs.androidx.constraintlayout) testImplementation(libs.junit) androidTestImplementation(libs.androidx.junit) androidTestImplementation(libs.androidx.espresso.core) // Add Google Play services for authentication implementation("com.google.android.gms:play-services-auth:20.4.1") } ``` Make sure to replace `"20.4.1"` with the latest version of the Google Play services library if necessary. After making these changes, sync your project with Gradle to ensure all dependencies are correctly downloaded and configured.

Changes on app/src/main/AndroidManifest.xml

To implement Google sign-in in your Android application, you need to update the `AndroidManifest.xml` file to include the necessary permissions and metadata. Here's how you can modify this file: 1. **Add Internet Permission**: Google sign-in requires internet access to communicate with Google's servers. You need to add the internet permission to your manifest file. 2. **Add Metadata for Google Services**: You need to include metadata for Google services configuration. This typically involves adding a `meta-data` tag with your Google API key or configuration file. Here's how you can update your `AndroidManifest.xml`: ```xml

``` **Note**: Replace `"YOUR_API_KEY_HERE"` with your actual Google API key. If you are using a `google-services.json` file for configuration, ensure it is placed in the appropriate directory, and the build process will automatically include the necessary metadata. This setup will ensure that your application has the necessary permissions and configuration to support Google sign-in.

Changes on app/src/main/java/afrion/scientificcalculator/MainActivity.kt

To implement Google sign-in logic in the `MainActivity.kt` file, follow these steps: 1. **Add Google Sign-In Dependencies**: Ensure that the necessary dependencies for Google Sign-In are added in your `build.gradle.kts` file. This typically includes the Google Play services library. 2. **Initialize GoogleSignInClient**: In the `onCreate` method, initialize the `GoogleSignInClient` with the appropriate options. This involves creating a `GoogleSignInOptions` object with the required parameters, such as the web client ID. 3. **Add Sign-In Button Logic**: Set up an `onClickListener` for the Google sign-in button. When clicked, it should trigger the sign-in intent using the `GoogleSignInClient`. 4. **Handle Sign-In Result**: Override the `onActivityResult` method to handle the result of the sign-in intent. Use `GoogleSignIn.getSignedInAccountFromIntent` to retrieve the sign-in result and handle success or failure accordingly. Here's a basic implementation outline: ```kotlin import android.content.Intent import com.google.android.gms.auth.api.signin.GoogleSignIn import com.google.android.gms.auth.api.signin.GoogleSignInClient import com.google.android.gms.auth.api.signin.GoogleSignInOptions import com.google.android.gms.common.api.ApiException class MainActivity : AppCompatActivity() { private lateinit var googleSignInClient: GoogleSignInClient override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) // Initialize Google Sign-In options val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN) .requestEmail() .build() // Build a GoogleSignInClient with the options specified by gso googleSignInClient = GoogleSignIn.getClient(this, gso) // Set up the sign-in button click listener val signInButton: Button = findViewById(R.id.sign_in_button) signInButton.setOnClickListener { signIn() } } private fun signIn() { val signInIntent = googleSignInClient.signInIntent startActivityForResult(signInIntent, RC_SIGN_IN) } override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) { super.onActivityResult(requestCode, resultCode, data) if (requestCode == RC_SIGN_IN) { val task = GoogleSignIn.getSignedInAccountFromIntent(data) try { val account = task.getResult(ApiException::class.java) // Signed in successfully, show authenticated UI. updateUI(account) } catch (e: ApiException) { // Sign in was unsuccessful, handle the error updateUI(null) } } } private fun updateUI(account: GoogleSignInAccount?) { if (account != null) { // User is signed in // Update UI with user information } else { // User is not signed in // Show sign-in options } } companion object { private const val RC_SIGN_IN = 9001 } } ``` Make sure to replace `R.id.sign_in_button` with the actual ID of your Google sign-in button in the layout file. Also, handle the UI updates in the `updateUI` method based on whether the user is signed in or not.

MUHOOZId / ScientificCalculator

Task Tile #2

Potential solution

How to implement